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NumPy: Test element-wise of a given array for finiteness, positive or negative infinity, for NaN, for NaT, for negative infinity, for positive infinity

NumPy Statistics: Exercise-11 with Solution

Write a NumPy program to test element-wise of a given array for finiteness (not infinity or not Not a Number), positive or negative infinity, for NaN, for NaT (not a time), for negative infinity, for positive infinity.

Sample Solution:-

Python Code:

import numpy as np
print("\nTest element-wise for finiteness (not infinity or not Not a Number):")
print(np.isfinite(1))
print(np.isfinite(0))
print(np.isfinite(np.nan))
print("\nTest element-wise for positive or negative infinity:")
print(np.isinf(np.inf))
print(np.isinf(np.nan))
print(np.isinf(np.NINF))
print("Test element-wise for NaN:")
print(np.isnan([np.log(-1.),1.,np.log(0)]))
print("Test element-wise for NaT (not a time):")
print(np.isnat(np.array(["NaT", "2016-01-01"], dtype="datetime64[ns]")))
print("Test element-wise for negative infinity:")
x = np.array([-np.inf, 0., np.inf])
y = np.array([2, 2, 2])
print(np.isneginf(x, y))
print("Test element-wise for positive infinity:")
x = np.array([-np.inf, 0., np.inf])
y = np.array([2, 2, 2])
print(np.isposinf(x, y))

Sample Output:

Test element-wise for finiteness (not infinity or not Not a Number):
True
True
False

Test element-wise for positive or negative infinity:
True
False
True
Test element-wise for NaN:
[ True False False]
Test element-wise for NaT (not a time):
[ True False]
Test element-wise for negative infinity:
[1 0 0]
Test element-wise for positive infinity:
[0 0 1]

Python-Numpy Code Editor:

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Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os
cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

  • The os and os.path modules.
  • The __file__ constant
  • os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
  • os.path.dirname(path) (returns "the directory name of pathname path")
  • os.getcwd() (returns "a string representing the current working directory")
  • os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m