import numpy as np
[docs]class Utils:
""" Utils class of the tf_G package.
This class contains static methods that will be used by another classes
around the package.
"""
@staticmethod
[docs] def ranked(x: np.ndarray) -> np.ndarray:
""" This method sorts the array indices given by its values.
It can be used to generate a ranking based on the values of an array in
which the value represents the score and the index the object identifier.
Args:
x (:obj:`np.ndarray`): A 2-D `np.ndarray` to rank the results by rows.
Returns:
(:obj:`np.ndarray`): An array containing the indices of the input array
sorted in decremental order.
"""
return np.argsort(x, axis=1)
@staticmethod
[docs] def save_ranks(filename: str, array: np.ndarray,
index_increment: bool = True) -> None:
""" This method will save the input array in the filesystem.
The method creates a file in the filesystem with name `filename` and puts
the array content inside it.
This method provides the `index_increment` that increments the first column
by one if True. The reason of this option is that the method is created to
store results of graph operations, and in some cases the graph vertices is
represented as 0-indexed and anothers as 1-indexed.
Args:
filename (str): The name of the file that will be created.
array (:obj:`np.ndarray`): The array that contains the data that will be
saved.
index_increment (bool, optional): Increments the first column of the array
input if True, do nothing otherwise.
Returns:
This method returns nothing.
"""
if index_increment:
array[:, 0] += 1
np.savetxt(filename, array, fmt='%i,%f',
header='vertex_id,page_rank', comments='')