Question

I have a numpy array and I want to delete the first 3 elements of the array. I tried this solution:

           a = np.arange(0,10)
           i=0
           while(i<3):
             del a[0]
             i=i+1

This gives me an error that “ValueError: cannot delete array elements“. I do not understand why this is the case. i’d appreciate the help thanks!

Answer 1

Numpy arrays have a fixed size, hence you cannot simply delete an element from them. The simplest way to achieve what you want is to use slicing:

a = a[3:]

This will create a new array starting with the 4th element of the original array.

For certain scenarios, slicing is just not enough. If you want to create a subarray consisting of specific elements from the original array, you can use another array to select the indices:

>>> a = arange(10, 20)
>>> a[[1, 4, 5]]
array([11, 14, 15])

So basically, a[[1,4,5]] will return an array that consists of the elements 1,4 and 5 of the original array.