How do i extract a value from a 2d array in python?

This article describes how to extract or delete elements, rows, and columns that satisfy the condition from the NumPy array ndarray.

• Extract elements that satisfy the conditions
• Extract rows and columns that satisfy the conditions
  • All elements satisfy the condition: numpy.all[]
  • At least one element satisfies the condition: numpy.any[]
• Delete elements, rows, and columns that satisfy the conditions
  • Use ~ [NOT]
  • Use numpy.delete[] and numpy.where[]
• Multiple conditions

See the following article for an example when ndarray contains missing values NaN.

• NumPy: Remove rows/columns with missing value [NaN] in ndarray

If you want to replace or count an element that satisfies the conditions, see the following article.

• numpy.where[]: Manipulate elements depending on conditions
• NumPy: Count the number of elements satisfying the condition

If you want to extract elements that meet the condition, you can use ndarray[conditional expression].

Even if the original ndarray is a multidimensional array, a flattened one-dimensional array is returned.

import numpy as np

a = np.arange[12].reshape[[3, 4]]
print[a]
# [[ 0  1  2  3]
#  [ 4  5  6  7]
#  [ 8  9 10 11]]

print[a