KeyMap

class KeyMap(key_cols, target_cols=None, name='')

A map of unique column values for remapping columns.

key_cols

A list of column names that will be hashed into the keys for the map.

Type:

list

target_cols

Optional list of column names that will be inserted into data and later remapped.

Type:

list or None

name

An optional name of this remap for identification purposes.

Type:

str

Notes: This mapping converts all columns in the mapping to strings. The remapping does not support other types of columns.

Methods

KeyMap.__init__(key_cols[, target_cols, name])	Information for remapping columns of tabular files.
KeyMap.make_template([additional_cols, ...])	Return a dataframe template.
KeyMap.remap(data)	Remap the columns of a dataframe or columnar file.
KeyMap.remove_quotes(df[, columns])	Remove quotes from the specified columns and convert to string.
KeyMap.resort()	Sort the col_map in place by the key columns.
KeyMap.update(data[, allow_missing])	Update the existing map with information from data.

Attributes

KeyMap.columns

Return the column names of the columns managed by this map.

KeyMap.__init__(key_cols, target_cols=None, name='')

Information for remapping columns of tabular files.

Parameters:

• key_cols (list) – List of columns to be replaced (assumed in the DataFrame).

• target_cols (list) – List of replacement columns (assumed to not be in the DataFrame).

• name (str) – Name associated with this remap (usually a pathname of the events file).

KeyMap.make_template(additional_cols=None, show_counts=True)

Return a dataframe template.

Parameters:

• additional_cols (list or None) – Optional list of additional columns to append to the returned dataframe.

• show_counts (bool) – If True, number of times each key combination appears is in first column and values are sorted in descending order by.

Returns:

A dataframe containing the template.

Return type:

DataFrame

Raises:

HedFileError –

• If additional columns are not disjoint from the key columns.

Notes

• The template consists of the unique key columns in this map plus additional columns.

KeyMap.remap(data)

Remap the columns of a dataframe or columnar file.

Parameters:

data (DataFrame, str) – Columnar data (either DataFrame or filename) whose columns are to be remapped.

Returns:

• DataFrame: New dataframe with columns remapped.

• list: List of row numbers that had no correspondence in the mapping.

Return type:

tuple

Raises:

HedFileError –

• If data is missing some of the key columns.

static KeyMap.remove_quotes(df, columns=None)

Remove quotes from the specified columns and convert to string.

Parameters:

• df (Dataframe) – Dataframe to process by removing quotes.

• columns (list) – List of column names. If None, all columns are used.

Notes

• Replacement is done in place.

KeyMap.resort()

Sort the col_map in place by the key columns.

KeyMap.update(data, allow_missing=True)

Update the existing map with information from data.

Parameters:

• data (DataFrame or str) – DataFrame or filename of an events file or event map.

• allow_missing (bool) – If True allow missing keys and add as n/a columns.

Raises:

HedFileError –

• If there are missing keys and allow_missing is False.

KeyMap.columns

Return the column names of the columns managed by this map.

Returns:

Column names of the columns managed by this map.

Return type:

list