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  2. Python | Multiply a two-dimensional array corresponding to a 1d array

Python | Multiply a two-dimensional array corresponding to a 1d array



Method # 1: Using np.newaxis ()

# Python code for demonstration
# multiplying a 2d array
# with a 1d array

 

import numpy as np

 

ini_array1 = np.array ([[ 1 , 2 , 3 ], [ 2 , 4 , 5 ], [ 1 , 2 , 3 ]])

ini_array2 = np.array ([ 0 , 2 , 3 ])

 
# printing initial arrays

print ( "initial array" , str (ini_array1))

 
# Multiplying arrays

result = ini_array1 * ini_array2 [:, np.newaxis]

 
# print result

print ( " New resulting array: " , result)

Exit:

 initial array [[1 2 3] [2 4 5] [1 2 3]] New resulting array: [[0 0 0] [4 8 10 ] [3 6 9]]

Method # 2: Using the Axis As Not

# Python code for demonstration
# multiplying a 2d array
# with a 1d array

 

import numpy as np

 

ini_array1 = np.array ([[ 1 , 2 , 3 ], [ 2 , 4 , 5 ], [ 1 , 2 , 3 ]])

ini_array2 = np.array ([ 0 , 2 , 3 ])

 
# printing initial arrays

print ( "initial array" , str (ini_array1))

 
# Multiplying arrays

result = ini_array1 * ini_array2 [:, None ]

 
# print result

print ( "New resulting array:" , result)

Exit:

 initial array [[1 2 3] [2 4 5] [1 2 3]] New resulting array: [[0 0 0] [4 8 10] [3 6 9]]

Spo ex # 3: Using transpose ()

# Python code for demonstration
# multiplying a 2d array
# with a 1d array

 

import numpy as np

 

ini_array1 = np.array ([ [ 1 , 2 , 3 ], [ 2 , 4 , 5 ], [ 1 , 2 , 3 ]])

ini_array2 = np.array ([ 0 , 2 , 3 ])

 
# printing initial arrays

print ( "initial array" , str (ini_array1))

 
# Multiplying arrays

result = (ini_array1.T * ini_array2) .T

 
# print result

print ( "New resulting array:" , result)

Exit: 

 initial array [[1 2 3] [2 4 5] [1 2 3]] New resulting array: [[0 0 0] [4 8 10] [3 6 9] ]