Dada la array numpy, la tarea es agregar filas/columnas según los requisitos de la array numpy. Veamos algunos ejemplos de este problema.
Método #1: Usar el método np.hstack()
Python3
# Python code to demonstrate # adding columns in numpy array import numpy as np ini_array = np.array([[1, 2, 3], [45, 4, 7], [9, 6, 10]]) # printing initial array print("initial_array : ", str(ini_array)); # Array to be added as column column_to_be_added = np.array([1, 2, 3]) # Adding column to numpy array result = np.hstack((ini_array, np.atleast_2d(column_to_be_added).T)) # printing result print ("resultant array", str(result))
Producción:
initial_array : [[ 1 2 3] [45 4 7] [ 9 6 10]] resultant array [[ 1 2 3 1] [45 4 7 2] [ 9 6 10 3]]
Método #2: Usar el método column_stack()
Python3
# python code to demonstrate # adding columns in numpy array import numpy as np ini_array = np.array([[1, 2, 3], [45, 4, 7], [9, 6, 10]]) # printing initial array print("initial_array : ", str(ini_array)); # Array to be added as column column_to_be_added = np.array([1, 2, 3]) # Adding column to numpy array result = np.column_stack((ini_array, column_to_be_added)) # printing result print ("resultant array", str(result))
Producción:
initial_array : [[ 1 2 3] [45 4 7] [ 9 6 10]] resultant array [[ 1 2 3 1] [45 4 7 2] [ 9 6 10 3]]
Método #3: Usar el método np.vstack()
Python3
# python code to demonstrate # adding rows in numpy array import numpy as np ini_array = np.array([[1, 2, 3], [45, 4, 7], [9, 6, 10]]) # printing initial array print("initial_array : ", str(ini_array)); # Array to be added as row row_to_be_added = np.array([1, 2, 3]) # Adding row to numpy array result = np.vstack ((ini_array, row_to_be_added) ) # printing result print ("resultant array", str(result))
Producción:
initial_array : [[ 1 2 3] [45 4 7] [ 9 6 10]] resultant array [[ 1 2 3] [45 4 7] [ 9 6 10] [ 1 2 3]]
A veces tenemos una array vacía y necesitamos agregarle filas. Numpy proporciona la función para agregar una fila a una array Numpy vacía usando la función numpy.append() .
Syntax : numpy.append(arr, values, axis=None)
Caso 1 : agregar filas nuevas a una array bidimensional vacía
Python3
# importing Numpy package import numpy as np # creating an empty 2d array of int type empt_array = np.empty((0,2), int) print("Empty array:") print(empt_array) # adding two new rows to empt_array # using np.append() empt_array = np.append(empt_array, np.array([[10,20]]), axis=0) empt_array = np.append(empt_array, np.array([[40,50]]), axis=0) print("\nNow array is:") print(empt_array)
Empty array: [] Now array is: [[10 20] [40 50]]
Caso 2 : agregar nuevas filas a una array tridimensional vacía
Python3
# importing Numpy package import numpy as np # creating an empty 3d array of int type empt_array = np.empty((0,3), int) print("Empty array:") print(empt_array) # adding three new rows to empt_array # using np.append() empt_array = np.append(empt_array, np.array([[10,20,40]]), axis=0) empt_array = np.append(empt_array, np.array([[40,50,55]]), axis=0) empt_array = np.append(empt_array, np.array([[40,50,55]]), axis=0) print("\nNow array is:") print(empt_array)
Empty array: [] Now array is: [[10 20 40] [40 50 55] [40 50 55]]
Caso 3 : agregar nuevas filas a una array 4-D vacía
Python3
# importing Numpy package import numpy as np # creating an empty 4d array of int type empt_array = np.empty((0,4), int) print("Empty array:") print(empt_array) # adding four new rows to empt_array # using np.append() empt_array = np.append(empt_array, np.array([[100,200,400,888]]), axis=0) empt_array = np.append(empt_array, np.array([[405,500,550,558]]), axis=0) empt_array = np.append(empt_array, np.array([[404,505,555,145]]), axis=0) empt_array = np.append(empt_array, np.array([[44,55,550,150]]), axis=0) print("\nNow array is:") print(empt_array)
Empty array: [] Now array is: [[100 200 400 888] [405 500 550 558] [404 505 555 145] [ 44 55 550 150]]
Publicación traducida automáticamente
Artículo escrito por garg_ak0109 y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA