Replace value in array with condition

Question

I have this simplified program to replace values in array which fulfill the conditions:

formula1=2*2
formula2=5*2
formula3=4*4
array = np.random.rand(2,4,10)
for n,i in enumerate(array):
 if i>0.5: #find value in array with this condition
 formula = formula1
 array[n] = array[n]*formula #replace the found value with this value
 elif i <0.1:
 formula = formula2
 array[n] = array[n]*formula
 else:
 formula = formula3
 array[n] = array[n]*formula
print array 

It resulted in error message:'The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()'. Any suggestion?

• syntonym: Can you add the complete traceback?
• F L: @syntonym if i<0.5: ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()
• SvbZ3r0: In your for loop, i is an array. How would you determine if an array is lesser than a given value? any() checks if any of the elements in the array is lesser than the given value and all() checks if all the elements are
• F L: @SvbZ3r0 isn't any() or all() used to find boolean value of True and False only?
• SvbZ3r0: Not necessarily. Try np.any(array<0.5) to see if any of the values in array are lesser than 0.5

Answer 1

To enumerate an array, you can use np.ndenumerate (documentation here):

for n, i in np.ndenumerate(array):
 ...