How to clamp an integer to some range?

Question

This is pretty clear, actually. Many folks learn it quickly. You can use a comment to help them.

new_index = max(0, min(new_index, len(mylist)-1))

sorted((minval, value, maxval))[1]

for example:

>>> minval=3
>>> maxval=7
>>> for value in range(10):
...   print sorted((minval, value, maxval))[1]
... 
3
3
3
3
4
5
6
7
7
7

many interesting answers here, all about the same, except... which one's faster?

import numpy
np_clip = numpy.clip
mm_clip = lambda x, l, u: max(l, min(u, x))
s_clip = lambda x, l, u: sorted((x, l, u))[1]
py_clip = lambda x, l, u: l if x < l else u if x > u else x

>>> import random
>>> rrange = random.randrange
>>> %timeit mm_clip(rrange(100), 10, 90)
1000000 loops, best of 3: 1.02 µs per loop

>>> %timeit s_clip(rrange(100), 10, 90)
1000000 loops, best of 3: 1.21 µs per loop

>>> %timeit np_clip(rrange(100), 10, 90)
100000 loops, best of 3: 6.12 µs per loop

>>> %timeit py_clip(rrange(100), 10, 90)
1000000 loops, best of 3: 783 ns per loop

paxdiablo has it!, use plain ol' python. The numpy version is, perhaps not surprisingly, the slowest of the lot. Probably because it's looking for arrays, where the other versions just order their arguments.

See numpy.clip:

index = numpy.clip(index, 0, len(my_list) - 1)

Chaining max() and min() together is the normal idiom I've seen. If you find it hard to read, write a helper function to encapsulate the operation:

def clamp(minimum, x, maximum):
    return max(minimum, min(x, maximum))