Reference link: numpy.delete in Python
Introduction:
The function of these three functions is to add or delete a row/column of a matrix or array, and then introduce the usage of the functions one by one.
import numpy as np
>>> a = np.array(np.arange(12).reshape(3,4))
>>> a
array([[ 0, 1, 2, 3],
[ 4, 5, 6, 7],
[ 8, 9, 10, 11]])
One, numpy.insert()
Function syntax:
numpy.insert(arr, obj, values, axis=None)
Function: Insert a vector into a row or column. Parameter description: arr: array input matrix obj: int inserted before the row/column values: array the matrix to be inserted axis: int insert a row (0) or column (1) Return value: Return an array inserted into the vector. If axis=None, return a flattened array example:
>>> np.insert(a,1,[0,0,0,0],0)
array([[ 0, 1, 2, 3],
[ 0, 0, 0, 0],
[ 4, 5, 6, 7],
[ 8, 9, 10, 11]])
>>> np.insert(a,1,[0,1,0],1)
array([[ 0, 0, 1, 2, 3],
[ 4, 1, 5, 6, 7],
[ 8, 0, 9, 10, 11]])
二、numpy.delete()
Function syntax:
numpy.delete(arr, obj, axis=None)
Function function: delete a row or column Parameter description: arr: array input matrix obj: int which row or column to delete axis: int delete row (0) or column (1) Return value: Return to delete a row/column array example:
>>> np.delete(a,0,1)
array([[ 1, 2, 3],
[ 5, 6, 7],
[ 9, 10, 11]])
>>> np.delete(a,2,0)
array([[0, 1, 2, 3],
[4, 5, 6, 7]])
三、numpy.append()
Function syntax:
numpy.append(arr, values, axis=None)
Function: Add a row/column to the end of the array. Parameter description: arr: array Input matrix values: array The matrix to be inserted axis: int According to row (0) or column (1) insertion example:
>>> np.append(a, [[1,2,3,4]], 0) #Pay attention to the form of insertion here
array([[ 0, 1, 2, 3],
[ 4, 5, 6, 7],
[ 8, 9, 10, 11],
[ 1, 2, 3, 4]])
>>> np.append(a,[[1],[2],[3]], 1)
array([[ 0, 1, 2, 3, 1],
[ 4, 5, 6, 7, 2],
[ 8, 9, 10, 11, 3]])