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Conditionally Selecting The Elements In An Array In Numpy






Example




import numpy as np

arr = np.arange(1,10)

# Check the array for numbers greater than 5
result =  arr > 5
print(arr[result])




  1. An array is created using the arange function with value from 1 to 9.
  2. Check the value of array greater than 5 using a single expression arr > 5 and put the result of the expression in an array ‘result’.
  3. The result will be a boolean array with true and false values
  4. Picture showing the boolean array that specifies the elements having value greater than 5

    Click to Enlarge

  5. The value from position 0 to 4 is false, because the value at these positions is less than 5. The value from 5 to 8 is true, because the value at these positions is greater than 5.
  6. Finally, printing the value of arr[result], which returns the value from position 5 to 8 (all true values).
  7. Picture showing an array with the elements having the value greater than 5

    Click to Enlarge




import numpy as np

arr = np.arange(1,10)

print(arr[arr> 5])




import numpy as np

arr = np.arange(1,10)

# Check the array for even numbers
result =  arr % 2 == 0
even_num_array = arr[result]

# Check the array for odd numbers
result =  arr % 2 != 0
odd_num_array = arr[result]

print("Even array", even_num_array)
print("Odd array", odd_num_array)



Posted By  -  Karan Gupta
 
Posted On  -  Friday, March 29, 2019

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