pept.utilities.group_by_column#

pept.utilities.group_by_column(data_array, column_to_separate)[source]#

Group the rows in a 2D data_array based on the unique values in a given column_to_separate, returning the groups as a list of numpy arrays.

Parameters

data_array(M, N) numpy.ndarray: A generic 2D numpy array-like (will be converted using numpy.asarray).
column_to_separateint: The column index in data_array from which the unique values will be used for grouping.

Returns

groupslist of numpy.ndarray: A list whose elements are 2D numpy arrays - these are sub-arrays from data_array for which the entries in the column column_to_separate are the same.

Raises

ValueError: If data_array does not have exactly 2 dimensions.

Examples

Separate a 6x3 numpy array based on the last column:

>>> x = np.array([
>>>     [1, 2, 1],
>>>     [5, 3, 1],
>>>     [1, 1, 2],
>>>     [5, 2, 1],
>>>     [2, 4, 2]
>>> ])
>>> x_sep = pept.utilities.group_by_column(x, -1)
>>> x_sep
>>> [array([[1, 2, 1],
>>>         [5, 3, 1],
>>>         [5, 2, 1]]),
>>>  array([[1, 1, 2],
>>>         [2, 4, 2]])]