Remove all occurrences of a value from a list?

Question

In Python remove() will remove the first occurrence of value in a list.

How to remove all occurrences of a value from a list?

This is w

Answer 1

Numpy approach and timings against a list/array with 1.000.000 elements:

Timings:

In [10]: a.shape
Out[10]: (1000000,)

In [13]: len(lst)
Out[13]: 1000000

In [18]: %timeit a[a != 2]
100 loops, best of 3: 2.94 ms per loop

In [19]: %timeit [x for x in lst if x != 2]
10 loops, best of 3: 79.7 ms per loop

Conclusion: numpy is 27 times faster (on my notebook) compared to list comprehension approach

PS if you want to convert your regular Python list lst to numpy array:

arr = np.array(lst)

Setup:

import numpy as np
a = np.random.randint(0, 1000, 10**6)

In [10]: a.shape
Out[10]: (1000000,)

In [12]: lst = a.tolist()

In [13]: len(lst)
Out[13]: 1000000

Check:

In [14]: a[a != 2].shape
Out[14]: (998949,)

In [15]: len([x for x in lst if x != 2])
Out[15]: 998949