indexers Package

indexers Package

active_voices Module

class vis.analyzers.indexers.active_voices.ActiveVoicesIndexer(score, settings=None)

Bases: vis.analyzers.indexer.Indexer

Indexer that counts the number of voices active at each offset. It can either find all voices sounding, or only the voices that are attacking, depending on the settings passed.

Call this indexer via the get_data() method of either an indexed_piece object or an aggregated_pieces object (see example below). If nothing is passed in the ‘data’ argument of the call to get_data(), then the default is to process the NoteRestIndexer results of the indexed_piece in question. You can pass some other DataFrame in the ‘data’ argument, but it is discouraged.

Parameters:

• 'attacked' (boolean) – When true, only counts the voices that are attacking at each offset. Defaults to false.
• 'show_all' (boolean) – When true, shows the results at all offsets, even if there is not change. Defaults to false.

Examples:

Prepare an indexed piece:

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('path_to_piece.xml')

Get the ActiveVoicesIndexer results with the default settings:

>>> ip.get_data('active_voices')

Get the ActiveVoicesIndexer results with specified settings:

>>> av_setts = {
        'attacked': True, 
        'show_all': True
    }
>>> ip.get_data('active_voices', settings=av_setts)

default_settings = {'show_all': False, 'attacked': False}

possible_settings = ['attacked', 'show_all']

required_score_type = 'pandas.DataFrame'

run()

Returns:new index of the active voices in the piece. Return type:pandas.DataFrame

vis.analyzers.indexers.active_voices.indexer1(x)

Used internally by the ActiveVoicesIndexer to count individualevents.

cadence Module

class vis.analyzers.indexers.cadence.CadenceIndexer(score, settings=None)

Bases: vis.analyzers.indexer.Indexer

Using OverBassIndexer and FermataIndexer results, finds cadences as lists of events in the approach to a fermata.

Call this indexer via the get_data() method of either an indexed_piece object or an aggregated_pieces object (see example below).

Parameters:

• 'length' (int) – The length of the cadence, or how many events happen before a fermata.
• 'voice' (str or int) – The voice in which you want to look for fermatas. The default value for this is ‘all’.

Example:

Prepare an indexed piece and import pandas:

>>> from vis.models.indexed_piece import Importer
>>> import pandas
>>> ip = Importer('path_to_piece.xml')

Prepare OverBassIndexer and FermataIndexer results. For more specific advice on how to do this, please see the documentation of those two indexers. These two DataFrames should be passed as a list. For simplicity, including the FermataIndexer results is optional, and this example shows how to use the CadenceIndexer without explicitly providing the FermataIndexer results, so the ‘data’ argument is a singleton list.

>>> overbass_input_dfs = [ip.get_data('noterest'), 
        ip.get_data('vertical_interval')]
>>> ob_setts = {
        'type': 'notes'
    }
>>> overbass = ip.get_data('over_bass', data=overbass_input_dfs, 
        settings=ob_setts)

Get the CadenceIndexer results with specified settings:

>>> ca_setts = {'length': 3}
>>> ip.get_data('cadence', data=[overbass], settings=ca_setts)

possible_settings = ['length', 'voice']

required_score_type = 'pandas.DataFrame'

run()

Makes a new index of the cadences in the piece.

Returns:A DataFrame of the cadences. Return type:pandas.DataFrame

contour Module

vis.analyzers.indexers.contour.COM_matrix(contour)

Creates a matrix representing the contour given.

class vis.analyzers.indexers.contour.ContourIndexer(score, settings=None)

Bases: vis.analyzers.indexer.Indexer

Indexes the contours of a given length in a piece, where contour is a way of numbering the relative heights of pitches, beginning at 0 for the lowest pitch.

Call this indexer via the get_data() method of either an indexed_piece object or an aggregated_pieces object (see example below). If nothing is passed in the ‘data’ argument of the call to get_data(), then the default is to process the NoteRestIndexer results of the indexed_piece in question. You can pass some other DataFrame to the ‘data’ argument, but it is discouraged.

Parameters:'length' (int) – This is the length of the contour you want to look at.

Example:

Prepare an indexed piece:

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('path_to_piece.xml')

Get the ContourIndexer results with specified settings and processing the notes and rests:

>>> notes = ip.get_data('noterest')
>>> contour_setts = {'length': 3}
>>> ip.get_data('contour', data=notes, settings=contour_setts)

possible_settings = ['length']

required_score_type = 'pandas.DataFrame'

run()

Makes a new index of the contours in the piece.

Returns:A DataFrame of the contours. Return type:pandas.DataFrame

vis.analyzers.indexers.contour.compare(contour1, contour2)

Additional method to compare COM_matrices.

vis.analyzers.indexers.contour.getContour(notes)

Method used internally by the ContourIndexer class to convert pitches into contour numbers.

dissonance Module

class vis.analyzers.indexers.dissonance.DissonanceIndexer(score, settings=None)

Bases: vis.analyzers.indexer.Indexer

Indexer that locates vertical dissonances between pairs of voices in a piece. It then categorizes intervals as consonant or dissonant and in the case of fourths (perfect or augmented) and diminished fifths it examines the other parts sounding with that fourth or fifth (if there are any) to see if the interval can be considered consonant. This dissonance analysis allows for the assignment of a dissonance type name or a consonance label for each voice at each offset. This last step is the DataFrame that gets returned.

The score type must be a list of dataframes of the results of the following indexers (order matters): beatstrength, duration, horizontal, vertical. To simplify things, however, it is better to use the get_data() on an indexed_piece object to get results from the dissonance indexer as per the example below.

The results of the disonance indexer are in the form of one cell in the resultant dataframe in each part at every offset where there is a new note, rest, or chord onset in any part. These cells contain one-character strings which are an abbreviation of what the dissonance type for that part at that moment is. The abbreviations correspoond to the following dissonance types:

• ‘Q’: Dissonant third quarter (special type of accented passing

  tone)

• ‘D’: Descending passing tone
• ‘R’: Ascending (“rising”) passing tone
• ‘L’: Lower neighbour
• ‘U’: Upper neighbour
• ‘S’: Suspension
• ‘F’: Fake suspension
• ‘f’: Diminished fake suspension
• ‘A’: Anticipation
• ‘C’: Nota cambiata
• ‘H’: Chanson idiom
• ‘E’: Echappée (escape tone)

• ‘-‘: Either no dissonance, or the part in question is not

  considered to be the dissonant note of the dissonance it’s in

Example:

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('symbolic_notation_file_location.xml')
>>> ip.get_data('dissonance')

check_4s_5s(pair_name, iloc_indx, suspect_diss, simuls)

This function evaluates whether P4’s, A4’s, and d5’s should be considered consonant based whether or not the lower voice of the suspect_diss forms an interval that causes us to deem the fourth or fifth consonant, as determined by the cons_makers list below. The function should be called once for each potentially consonant fourth or fifth.

Parameters:

• pair_name (String in the format '0,2' if the pair in question is S and T in an SATB texture.) – Name of pair that has the potentially consonant fourth or fifth.
• iloc_indx (Integer.) – Pandas iloc number of interval’s row in dataframe.
• suspect_diss (String.) – Interval name with quality and direction (i.e. nothing or ‘-‘) that corresponds to the fourth or fifth to be examined.

Returns:

string representing analysis of fourth or fifth in question where a ‘C’ or ‘D’ has been prepended to the interval name with quality to show that it was considered consonant or dissonant respectively.

Return type:

string

classify(indx, pair, event, prev_event)

Checks the dissonance definitions to find a suitable label for the dissonance passed. If no identifiable dissonance type matches, returns an unknown dissonance label. Omits checking the pair if either voice was previously given a known dissonance label still in vigour at the given offset. It only takes its four arguments to pass them on to the dissonance-type functions it calls.

Returns:A 5-tuple that can be unpacked to assign separate labels for each voice in the pair. If none of the known dissonance types were detected the 5-tuple will have the labels to mark one or both of the voices as dissonant. Return type:tuple

required_score_type = 'pandas.DataFrame'

run()

Make a new index of the piece which consists of a DataFrame with as many columns as there are voices in the piece. The index is the offset of the dissonance analyses. Another DataFrame (diss_ints) is calculated but not returned. It is in the same format as the IntervalIndexer (i.e. a DataFrame of Series where each series corresponds to the intervals in a given voice pair). The difference between this and the interval indexer is that this one figures out whether fourths or diminished fifths should be considered consonant for the purposes of dissonance classification. diss_ints is not calculated separately because it essentially consists of the same loop needed for dissonance classification.

Returns:A DataFrame of the new indices. The columns have a MultiIndex. Return type:pandas.DataFrame

fermata Module

Index fermatas.

class vis.analyzers.indexers.fermata.FermataIndexer(score, settings=None)

Bases: vis.analyzers.indexer.Indexer

Index Fermata.

Finds :class:`~music21.expressions.Fermata`s.

Example:

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('pathnameToScore.xml')
>>> ip.get_data('fermata')

required_score_type = 'stream.Part'

vis.analyzers.indexers.fermata.indexer_func(event)

Used internally by FermataIndexer. Inspects

Note and Rest and

returns u'Fermata' if a fermata is associated, else NaN.

Parameters:event (iterable of music21.note.Note or music21.note.Rest) – An iterable (nominally a Series) with an object to convert. Only the first object in the iterable is processed. Returns:If the first object in the list is a contains a Fermata, string u'Fermata' is returned. Else, NaN. Return type:str

interval Module

Index intervals. Use the IntervalIndexer to find vertical (harmonic) intervals between two parts. Use the HorizontalIntervalIndexer to find horizontal (melodic) intervals in the same part.

class vis.analyzers.indexers.interval.HorizontalIntervalIndexer(score, settings=None)

Bases: vis.analyzers.indexers.interval.IntervalIndexer

Use music21.interval.Interval to create an index of the horizontal (melodic) intervals in a single part. You should provide the result of NoteRestIndexer. Alternatively you could provide the results of the :class:’~vis.analyzers.offset.FilterByOffsetIndexer’ if you want to check for horizontal intervals at regular durational intervals. These settings apply to the HorizontalIntervalIndexer in addition to the settings available from the IntervalIndexer.

Parameters:

• 'simple or compound' (str) – Whether intervals should be represented in their single-octave form (either 'simple' or 'compound').
• or string 'quality' (bool) – Whether to display diatonic intervals without quality (either False or “diatonic no quality”), diatonic intervals with quality (either True or ‘diatonic with quality’), chromatic intervals (use ‘chromatic’), or interval class intervals (use ‘interval class’).
• 'directed' (boolean) – Whether we distinguish between which note is higher than the other. If True (default), prepends a ‘-‘ before everything else if the first note passed is higher than the second.
• 'horiz_attach_later' (boolean) – If True, the offset for a horizontal interval is the offset of the later note in the interval. The default is False, which gives horizontal intervals the offset of the first note in the interval.
• 'mp' (boolean) –

  Multiprocesses when True (default) or

  processes serially when False.

  Example:

>>> from vis.models.indexed_piece import Importer
>>> settings = {
        'quality': 'interval class', 
        'simple or compound': 'simple', 
        'directed': False
    }
>>> ip = Importer('pathnameToScore.xml')
>>> ip.get_data('horizontal_interval', settings)

default_settings = {'directed': True, 'simple or compound': 'compound', 'horiz_attach_later': False, 'quality': False, 'mp': True}

run()

Make a new index of the piece.

Returns:The new indices. Refer to the example below. Return type:pandas.DataFrame

class vis.analyzers.indexers.interval.IntervalIndexer(score, settings=None)

Bases: vis.analyzers.indexer.Indexer

Use music21.interval.Interval to create an index of the vertical (harmonic) intervals between two-part combinations.

You should provide the result of the NoteRestIndexer. However, to increase your flexibility, the constructor requires only a list of Series. You may also provide a DataFrame exactly as outputted by the NoteRestIndexer. The settings for the IntervalIndexer are as follows:

Parameters:

• 'simple or compound' (str) – Whether intervals should be represented in their single-octave form (either 'simple' or 'compound').
• or string 'quality' (bool) – Whether to display diatonic intervals without quality (either False or “diatonic no quality”), diatonic intervals with quality (either True or ‘diatonic with quality’), chromatic intervals (use ‘chromatic’), or interval class intervals (use ‘interval class’).
• 'directed' (boolean) – Whether we distinguish between which note is higher than the other. If True (default), prepends a ‘-‘ before everything else if the first note passed is higher than the second.
• 'mp' (boolean) – Multiprocesses when True (default) or processes serially when False.

Example:

>>> from vis.models.indexed_piece import Importer
>>> settings = {
        'quality': 'chromatic', 
        'simple or compound': 'simple', 
        'directed': True
    }
>>> ip = Importer('pathnameToScore.xml')
>>> ip.get_data('vertical_interval', settings)

default_settings = {'directed': True, 'simple or compound': 'compound', 'quality': False, 'mp': True}

required_score_type = 'pandas.DataFrame'

run()

Make a new index of the piece.

Returns:A DataFrame of the new indices. The columns have a MultiIndex; refer to the example below for more details. Return type:pandas.DataFrame

class vis.analyzers.indexers.interval.IntervalReindexer(score, settings=None)

Bases: vis.analyzers.indexers.interval.HorizontalIntervalIndexer

This indexer is only meant to ever be called indirectly to simplify caching of the results of the IntervalIndexer and the HorizontalIntervalIndexer. It takes the most information-rich type of interval analysis we offer (i.e. compound, directed intervals with diatonic quality) and re-indexes them to match whatever settings the user has requested. This is much faster, because it takes an entire interval as its input, rather than two notes, and therefore there are considerably fewer memos in its memoization scheme.

run()

meter Module

Indexers for metric concerns.

class vis.analyzers.indexers.meter.DurationIndexer(score, part_streams)

Bases: vis.analyzers.indexer.Indexer

Make an index of the durations of all Note, Rest, and Chord objects. These are calculated based on the difference in index positions of consecutive events.

Note

Unlike nearly all other indexers, this indexer returns a Series of float objects rather than unicode objects. Also unlike most other indexers, this indexer does not have an indexer func.

Example:

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('pathnameToScore.xml')
>>> ip.get_data('duration')

required_score_type = 'pandas.DataFrame'

run()

Make a new index of the piece.

Returns:The new indices of the durations of each note or rest event in a score. Note that each item is a float, rather than the usual basestring. Return type:pandas.DataFrame

class vis.analyzers.indexers.meter.MeasureIndexer(score)

Bases: vis.analyzers.indexer.Indexer

Make an index of the measures in a piece. Time signatures changes do not cause a problem. Note that unlike most other indexers this one returns integer values >= 0. Using music21’s part.measureTemplate() function is an alternative but it turned out to be much less efficient to looping over the piece and doing it this way makes this indexer just like all the other stream indexers in VIS.

Example:

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('pathnameToScore.xml')
>>> ip.get_data('measure')

required_score_type = 'pandas.DataFrame'

class vis.analyzers.indexers.meter.NoteBeatStrengthIndexer(score)

Bases: vis.analyzers.indexer.Indexer

Make an index of the beatStrength for all Note, Rest, and Chord objects.

Note

Unlike nearly all other indexers, this indexer returns a Series of float objects rather than unicode objects.

Example:

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('pathnameToScore.xml')
>>> ip.get_data('beat_strength')

required_score_type = 'pandas.DataFrame'

vis.analyzers.indexers.meter.beatstrength_ind_func(event)

Used internally by NoteBeatStrengthIndexer. Convert Note and Rest objects into a string.

Parameters:event – A music21 note, rest, or chord object which get queried for its beat strength. :type event: A music21 note, rest, or chord object or NaN. Returns:The beatStrength of the event which is dependent on the prevailing time signature. Return type:float

vis.analyzers.indexers.meter.measure_ind_func(event)

The function that indexes the measure numbers of each part in a piece. Unlike most other indexers, this one returns int values. Measure numbering starts from 1 unless there is a pick-up measure which gets the number 0. This can handle changes in time signature without problems.

Parameters:event (A music21 measure object or NaN.) – A music21 measure object which get queried for its “number” attribute. Returns:The number attribute of the passed music21 measure. Return type:int

ngram Module

Indexer to find k-part any-object n-grams. This file is a re-implimentation of the previous ngram_indexer.py file.

class vis.analyzers.indexers.ngram.NGramIndexer(score, settings=None)

Bases: vis.analyzers.indexer.Indexer

Indexer that finds k-part n-grams from other indices.

The indexer requires at least one “vertical” index, and supports “horizontal” indices that seem to “connect” instances in the vertical indices. Although we use “vertical” and “horizontal” to describe these index types, because the class is an abstraction of two-part interval n-grams, you can supply any information as either type of index. If you want one-part melodic n-grams for example, you should supply the relevant interval information as the “vertical” component. The “vertical” and “horizontal” indices can contain an arbitrary number of observations that can get condensed into one value or kept separate in different columns. There is no relationship between the number of index types, though there must be at least one “vertical” index.

The 'vertical' and 'horizontal' settings determine which columns of the dataframes in score are included in the n-gram output. score is a list of two dataframes, the vertical observations DataFrame and the horizontal observations DataFrame.

The format of the vertical and horizontal settings is very important and will decide the structure of the resulting n-gram results. Both the vertical and horizontal settings should be a list of tuples. If the optional horizontal setting is passed, its list should be of the same length as that of the vertical setting. Inside of each tuple, enter the column names of the observations that you want to include in each value. For example, if you want to make 3-grams of notes in the tenor in a four-voice choral, use the following settings (NB: there is no horizontal element in this simple query so no horizontal setting is passed. In this scenario you would need to pass the noterest indexer results as the only dataframe in the “score” list of dataframes.):

>>> settings = {
        'n': 3, 
        'vertical': [('2',)]
    }

If you want to look at the 4-grams in the interval pairs between the bass and soprano of a four-voice choral and track the melodic motions of the bass, the score argument should be a 2-item list containing the IntervalIndexer results dataframe and the HorizontalIntervalIndexer dataframe. Note that the HorizontalIntervalIndexer results must have been calculated with the 'horiz_attach_later' setting set to True (this is in order to avoid an indexing nightmare). The settings dictionary to pass to this indexer would be:

>>> settings = {
        'n': 4, 
        'vertical': [('0,3',)], 
        'horizontal': [('3',)]
    }

If you want to get ‘figured-bass’ 2-gram output from this same 4-voice choral, use the same 2-item list for the score argument, and then put all of the voice pairs that sound against the bass in the same tuple in the vertical setting. Here’s what the settings should be:

>>> settings = {
        'n': 2, 
        'vertical': [('0,3', '1,3', '2,3')], 
        'horizontal': [('3',)]
    }

In the example above, if you wanted stacks of vertical events without the horizontal connecting events, you would just omit the 'horizontal' setting from the settings dictionary and also only include the vertical observations in the score list of dataframes.

If instead you want to look at all the pairs of voices in the 4-voice piece, and always track the melodic motions of the lowest voice in that pair, then put each pair in a different tuple, and in the voice to track melodically in the corresponding tuple in the horizontal list. Since there are 6 pairs of voices in a 4-voice piece, both your vertical and horizontal settings should be a list of six tuples. This will cause the resulting n-gram results dataframe to have six columns of observations. Your settings should look like this:

>>> settings = {
        'n': 2, 'vertical': [
            ('0,1',), 
            ('0,2',), 
            ('0,3',), 
            ('1,2',), 
            ('1,3',), 
            ('2,3')
        ], 
        'horizontal': [
            ('1',), 
            ('2',), 
            ('3',), 
            ('2',), 
            ('3',), 
            ('3',)
        ]
    }

Since we often want to look at all the pairs of voices in a piece, you can set the 'vertical' setting to 'all' and this will get all the column names from the first dataframe in the score list of dataframes. Similarly, as we often want to always track the melodic motions of the lowest or highest voice in the vertical groups, the horizontal setting can be set to 'highest' or 'lowest' to automate this voice selection. This means that the preceeding query can also be accomplished with the following settings:

>>> settings = {
        'n': 2, 
        'vertical': 'all', 
        'horizontal': 'lowest'
    }

The 'brackets' setting will set off all the vertical events at each time point in square brackets ‘[]’ and horizontal observations will appear in parentheses ‘()’. This is particularly useful if there are multiple observations in each vertical or horizontal slice. For example, if we wanted to redo the query above where n = 4, but this time tracking the melodic motions of both the upper and the lower voice, it would be a good idea to set ‘brackets’ to True to make the results easier to read. The settings would look like this:

>>> settings = {
        'n': 4, 
        'vertical': [('0,3',)], 
        'horizontal': [('0', '3',)], 
        'brackets': True
    }

If you want n-grams to terminate when finding one or several particular values, you can specify this by passing a list of strings as the 'terminator' setting.

To show that a horizontal event continues, we use '_' by default, but you can set this separately, for example to 'P1' '0', as seems appropriate.

Once you’ve chosen the appropriate settings, to actually run the indexer call it like this:

Example:

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('pathnameToScore.xml')
>>> ngram_settings = {
        'n': 2, 
        'vertical': 'all', 
        'horizontal': 'lowest'
    }
>>> vert_settings = {
        'quality': 'chromatic', 
        'simple or compound': 'simple', 
        'directed': True
    }
>>> horiz_settings = {
        'quality': 'diatonic with quality', 
        'simple or compound': 'simple', 
        'directed': True, 
        'horiz_attach_later': True
    }
>>> vert_ints = ip.get_data('vertical_interval', settings=vert_settings)
>>> horiz_ints = ip.get_data('horizontal_interval', settings=horiz_settings)
>>> ip.get_data('ngram', data=[vert_ints, horiz_ints], settings=ngram_settings)

default_settings = {'open-ended': False, 'vertical': 'all', 'brackets': True, 'continuer': '_', 'terminator': [], 'horizontal': [], 'align': 'left'}

possible_settings = ['horizontal', 'vertical', 'n', 'open-ended', 'brackets', 'terminator', 'continuer', 'align']

A list of possible settings for the NGramIndexer.

Parameters:

• 'horizontal' (list of tuples of strings, default []) – Selectors for the columns to consider as “horizontal.”
• 'vertical' (list of tuples of strings, default 'all'.) – Selectors for the column names to consider as “vertical.”
• 'n' (int) – The number of “vertical” events per n-gram.
• 'open-ended' (boolean, default False.) – Appends the next horizontal observation to n-grams leaving them open-ended.
• 'brackets' (bool, default True.) – Whether to use delimiters around event observations. Square brakets [] are used to set off vertical events and round brackets () are used to set off horizontal events. This is particularly important to leave as True (default) for better legibility when there are multiple vertical or multiple horizontal observations at each slice.
• 'terminator' (list of str, default []) – Do not find an n-gram with a vertical item that contains any of these values.
• 'continuer' (str, default '_'.) – When there is no “horizontal” event that corresponds to a vertical event, this is printed instead, to show that the previous “horizontal” event continues.

required_score_type = 'pandas.DataFrame'

run()

Make an index of k-part n-grams of anything.

Returns:A new index of the piece in the form of a class:~pandas.DataFrame with as many columns as there are tuples in the ‘vertical’ setting of the passed settings.

noterest Module

Index note and rest objects into pandas DataFrame(s).

class vis.analyzers.indexers.noterest.MultiStopIndexer(score)

Bases: vis.analyzers.indexer.Indexer

Index Note, Rest, and Chord objects in a DataFrame.

Rest objects become 'Rest', and Note objects become the string-format version of their nameWithOctave attribute. Chord objects get unpacked into their constituent pitches.

This indexer is meant to be called indirectly with a call to get_data on an indexed piece in the manner of the following example.

Example:

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('path_to_piece.xml')
>>> ip.get_data('multistop')

required_score_type = 'pandas.DataFrame'

run()

Make a new index of the note and rest names in the piece. When a single part has chord objects, those chords get separated out into as many columns as there are notes in the chord with the greatest number of notes. This means that there can be more columns in this dataframe than there are parts in the piece.

Returns:A DataFrame of the new indices. The columns have a MultiIndex. Return type:pandas.DataFrame

class vis.analyzers.indexers.noterest.NoteRestIndexer(score)

Bases: vis.analyzers.indexer.Indexer

Index Note and Rest objects in a Part.

Rest objects become 'Rest', and Note objects become the string-format version of their nameWithOctave attribute.

This indexer is meant to be called indirectly with a call to get_data on an indexed piece in the manner of the following example.

Example:

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('path_to_piece.xml')
>>> ip.get_data('noterest')

required_score_type = 'pandas.DataFrame'

vis.analyzers.indexers.noterest.multistop_ind_func(event)

Used internally by MultiStopIndexer. Convert Note and Rest objects into a string and convert the Chord objects into a list of the strings of their consituent pitch objects. The results must be contained in a tuple or a list so that chords can later be unpacked into different 1-voice strands.

Parameters:event (A music21 note, rest, or chord object.) – A music21 note, rest, or chord object which get queried for their names. Returns:A one-tuple containing a string representation of the note or rest, or if the event is a chord, a list of the strings of the names of its constituent pitches. Return type:1-tuple of str or list of strings

Examples:

>>> from noterest.py import indexer_func
>>> from music21 import note, 
>>> indexer_func(note.Note('C4'))
(u'C4',)
>>> indexer_func(note.Rest())
(u'Rest',)
>>> indexer_func(chord.Chord([note.Note('C4'), note.Note('E5')]))
[u'C4', u'E5']

vis.analyzers.indexers.noterest.noterest_ind_func(event)

Used internally by NoteRestIndexer. Convert Note, Rest, and If you want to keep all the pitches in chords, consider using the :class:`MultiStopIndexer instead.

Parameters:event (A music21 note, rest, or chord object.) – A music21 note, rest, or chord object which get queried for their names. Returns:A one-tuple containing a string representation of the note or rest, or if the event is a chord, a list of the strings of the names of its constituent pitches. Return type:1-tuple of str or list of strings

Examples:

>>> from noterest.py import indexer_func
>>> from music21 import note, 
>>> indexer_func(note.Note('C4'))
u'C4'
>>> indexer_func(note.Rest())
u'Rest'
>>> indexer_func(chord.Chord([note.Note('E5'), note.Note('C4')]))
u'E5'

vis.analyzers.indexers.noterest.unpack_chords(df)

The c in nrc in methods like _get_m21_nrc_objs() stands for chord. This method unpacks music21 chords into a list of their constituent pitch objects. These pitch objects can be queried for their nameWithOctave in the same way that note objects can in music21. This works by broadcasting the list of pitches in each chord object in each part’s elements to a dataframe of note, pitch, and rest objects. So each part that had chord objects in it gets represented as a dataframe instead of just a series. Then the series from the parts that didn’t have chords in them get concatenated with the parts that did, resulting in potentially more columns in the final dataframe then there are parts in the score.

offset Module

Indexers that modify the “offset” values (floats stored as the “index” of a pandas.Series), potentially adding repetitions of or removing pre-existing events, without modifying the events themselves.

class vis.analyzers.indexers.offset.FilterByOffsetIndexer(score, settings=None)

Bases: vis.analyzers.indexer.Indexer

Indexer that regularizes the “offset” values of observations from other indexers.

The Indexer regularizes observations from offsets spaced any, possibly irregular, quarterLength durations apart, so they are instead observed at regular intervals. This has two effects:

• events that do not begin at an observed offset will only be included in the output if no other event occurs before the next observed offset
• events that last for many observed offsets will be repeated for those offsets

Since elements’ durations are not recorded, the last observation in a Series will always be included in the results. If it does not start on an observed offset, it will be included as the next observed offset—again, whether or not this is true in the actual music. However, the last observation will only ever be counted once, even if a part ends before others in a piece with many parts. See the doctests for examples.

Examples:

For all, the quarterLength is 1.0.

When events in the input already appear at intervals of quarterLength, input and output are identical.

offset	0.0	1.0	2.0
input	a	b	c
output	a	b	c

When events in the input appear at intervals of quarterLength, but there are additional elements between the observed offsets, those additional elements are removed.

offset	0.0	0.5	1.0	2.0
input	a	A	b	c
output	a		b	c

offset	0.0	0.25	0.5	1.0	2.0
input	a	z	A	b	c
output	a			b	c

When events in the input appear at intervals of quarterLength, but not at every observed offset, the event from the previous offset is repeated.

offset	0.0	1.0	2.0
input	a		c
output	a	a	c

When events in the input appear at offsets other than those observed by the specified quarterLength, the “most recent” event will appear.

offset	0.0	0.25	0.5	1.0	2.0
input	a	z	A		c
output	a			A	c

When the final event does not appear at an observed offset, it will be included in the output at the next offset that would be observed, even if this offset does not appear in the score file to which the results correspond.

offset	0.0	1.0	1.5	2.0
input	a	b	d
output	a	b		d

The behaviour in this last example can create a potentially misleading result for some analytic situations that consider meter. It avoids another potentially misleading situation where the final chord of a piece would appear to be dissonant because of a suspension. We chose to lose metric and rythmic precision, which would be more profitably analyzed with indexers built for that purpose. Consider this illustration, where the numbers correspond to scale degrees.

offset	410.0	411.0	411.5	412.0
in-S	2	1
in-A	7	5
in-T	4 ———–		3
in-B	5	1
out-S	2	1		1
out-A	7	5		5
out-T	4	4		3
out-B	5	1		1

If we left out the note event appear in the in-A part at offset 411.5, the piece would appear to end with a dissonant sonority!

default_settings = {'method': 'ffill', 'mp': True}

possible_settings = ['quarterLength', 'method', 'mp']

A list of possible settings for the FilterByOffsetIndexer.

Parameters:

• 'quarterLength' (float) – The quarterLength duration between observations desired in the output. This value must not have more than three digits to the right of the decimal (i.e. 0.001 is the smallest possible value).
• 'method' (str or None) – The value passed as the method kwarg to reindex(). The default is 'ffill', which fills in missing indices with the previous value. This is useful for vertical intervals, but not for horizontal, where you should use None instead.
• 'mp' (boolean) – Multiprocesses when True (default) or processes serially when False.

Examples:

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('path_to_piece.xml')
>>> notes = ip.get_data('noterest')
>>> setts = {'quarterLength': 2}
>>> ip.get_data('offset', data=notes, settings=setts)

# Note that other analysis results can be passed to the offset # indexer too, such as the IntervalIndexer results as in the # following example. Also, the original column names (or names of # the series if a list of series was passed) are retained, though # the highest level of the columnar multi-index gets overwritten

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('path_to_piece.xml')
>>> intervals = ip.get_data('vertical_interval')
>>> setts = {'quarterLength': 2}
>>> ip.get_data('offset', data=intervals, settings=setts)

required_score_type = 'pandas.Series'

The FilterByOffsetIndexer uses pandas.Series objects.

run()

Regularize the observed offsets for the Series input.

Returns:A DataFrame with offset-indexed values for all inputted parts. The pandas indices (holding music21 offsets) start at the first offset at which there is an event in any of the inputted parts. An offset appears every quarterLength until the final offset, which is either the last observation in the piece (if it is divisible by the quarterLength) or the next-highest value that is divisible by quarterLength. Return type:pandas.DataFrame

over_bass Module

class vis.analyzers.indexers.over_bass.OverBassIndexer(score, settings=None)

Bases: vis.analyzers.indexer.Indexer

Using horizontal events and vertical intervals, this finds the intervals over the bass motion.

Call this indexer via the get_data() method of either an indexed_piece object or an aggregated_pieces object (see examples below). The DataFrames passed in the ‘score’ argument should be concatenated

Parameters:

• 'horizontal' (int) – The horizontal voice you wish to use as a bass. If not indicated, this is automatically assigned to the lowest voice.
• 'type' (str) – The type of horizontal event you wish to index. The default is ‘notes’, which should be used if you are passing in the results of the NoteRestIndexer. If you are passing in the results of the HorizontalIntervalIndexer.

Example:

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('path_to_piece.xml')

This example provides note names for the tracked voice (usually the bass voice):

>>> input_dfs = [ip.get_data('noterest'), 
        ip.get_data('vertical_interval')]
>>> ob_setts = {'type': 'notes'}
>>> ip.get_data('over_bass', data=input_dfs, settings=ob_setts)

To use the OverBassIndexer with the melodic intervals of the tracked voice instead, do this:

>>> input_dfs = [ip.get_data('horizontal_interval'), 
        ip.get_data('vertical_interval')]
>>> ob_setts = {'type': 'intervals'}
>>> ip.get_data('over_bass', data=input_dfs, settings=ob_setts)

possible_settings = ['horizontal', 'type']

required_score_type = 'pandas.DataFrame'

run()

Make a new index of the intervals over the bass motion.

Returns:A DataFrame of the intervals over the bass. Return type:pandas.DataFrame

repeat Module

Indexers that consider repetition in any way.

class vis.analyzers.indexers.repeat.FilterByRepeatIndexer(score, settings=None)

Bases: vis.analyzers.indexer.Indexer

If the same event occurs many times in a row, remove all occurrences but the one with the lowest offset value (i.e., the “first” event).

Because of how a DataFrame‘s index works, many of the events that would have been filtered will instead be replaced with numpy.NaN. Please be careful that the behaviour of this indexer matches your expectations.

Example:

Prepare an indexed piece:

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('path_to_piece.xml')

This example filters the repeats out of the NoteRestIndexer results, but any can be passed:

>>> notes = ip.get_data('noterest')
>>> ip.get_data('repeat', data=notes)

required_score_type = 'pandas.Series'

run()

Make a new index of the piece, removing any event that is identical to the preceding.

Returns:A DataFrame of the new indices. Return type:pandas.DataFrame

template Module

Template for writing a new indexer. Use this class to help write a new :class`Indexer` subclass. The TemplateIndexer does nothing, and should only be used by programmers.

Note

Follow these instructions to write a new Indexer subclass:

1. Replace my name with yours in the “codeauthor” directive above.
2. Change the “Filename” and “Purpose” on lines 7 and 8.

3. Modify the “Copyright” on line 10 or add an additional

   copyright line immediately below.

4. Remove the # pylint: disable=W0613 comment just before

   indexer_func().

5. Rename the class.
6. Adjust required_score_type.

7. Add settings to possible_settings and

   default_settings, as required.

8. Rewrite the documentation for __init__().
9. Rewrite the documentation for run().
10. Rewrite the documentation for indexer_func().

11. Write all relevant tests for __init__(),

    run(), and indexer_func().

12. Follow the instructions in __init__() to write that method.

13. Follow the instructions in run() to write

    that method.

14. Write a new indexer_func().
15. Ensure your tests pass, adding additional ones as required.
16. Finally, run pylint with the VIS style rules.

class vis.analyzers.indexers.template.TemplateIndexer(score, settings=None)

Bases: vis.analyzers.indexer.Indexer

Template for an Indexer subclass.

default_settings = {}

The default values for settings named in possible_settings. If a setting doesn’t have a value in this constant, then it must be specified to the constructor at runtime, or the constructor should raise a RuntimeException.

possible_settings = ['fake_setting']

This is a list of string that are the names of the settings used in this indexer. Specify the types and reasons for each setting as though it were an argument list, like this:

Parameters:'fake_setting' (boolean) – This is the description of a fake setting.

required_score_type = 'stream.Part'

Depending on how this indexer works, you must provide a DataFrame, a Score, or list of Part or Series objects. Only choose Part or Series if the input will always have single-integer part combinations (i.e., there are no combinations—it will be each part independently).

run()

Make a new index of the piece.

Returns:The new indices. Refer to the note below. Return type:pandas.DataFrame or list of pandas.Series

Important

Please be sure you read and understand the rules about return values in the full documentation for run() and make_return().

vis.analyzers.indexers.template.indexer_func(obj)

The function that indexes.

Parameters:obj (list of objects of the types stored in TemplateIndexer._types) – The simultaneous event(s) to use when creating this index. (For indexers using a Score).

or

Parameters:obj (pandas.Series of strings) – The simultaneous event(s) to use when creating this index. (For indexers using a Series). Returns:The value to store for this index at this offset. Return type:str

windexer Module

class vis.analyzers.indexers.windexer.Windexer(score, settings=None)

Bases: vis.analyzers.indexer.Indexer

Indexer that creates new a new windowed version of other indexer results.

Parameters:'window_size' (integer) – The size of the window of the DataFrame that you would like to look at. The default setting is 4.

Example:

Prepare an indexed piece:

>>> from vis.models.indexed_piece import Importer
>>> ip = Importer('path_to_piece.xml')

This example prepares “windows” of notes and rests, but any dataframe could be used:

>>> notes = ip.get_data('noterest')
>>> setts = {'window_size': 4}
>>> ip.get_data('windexer', data=notes, settings=setts)

default_settings = {'window_size': 4}

possible_settings = ['window_size']

required_score_type = 'pandas.DataFrame'

run()

Make a new windowed index of the indexer results.

Returns:The new windowed DataFrame. Return type:pandas.DataFrame