How to clamp an integer to some range

Question

I have the following code   new index   index   offset if new index  lt  0      new index   0 if new index  gt   len mylist       new index   len mylist  - 1 return mylist new index    Basically  I calculate a new index and use that to find some element from a list  In order to make sure the index is inside the bounds of the list  I needed to write those 2 if statements spread into 4 lines  That s quite verbose  a bit ugly    Dare I say  it s quite un-pythonic   Is there any other simpler and more compact solution   and more pythonic   Yes  i know I can use if else in one line  but it is not readable   new index   0 if new index  lt  0 else len mylist  - 1 if new index  gt   len mylist  else new index   I also know I can chain max   and min   together  It s more compact  but I feel it s kinda obscure  more difficult to find bugs if I type it wrong  In other words  I don t find it very straightforward   new index   max 0  min new index  len mylist -1

User · Answer

Avoid writing functions for such small tasks, unless you apply them often, as it will clutter up your code.

for individual values:

min(clamp_max, max(clamp_min, value))

for lists of values:

map(lambda x: min(clamp_max, max(clamp_min, x)), values)

User · Answer

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

User · Answer

Whatever happened to my beloved readable Python language   -   Seriously  just make it a function   def addInRange val  add  minval  maxval       newval   val   add     if newval  lt  minval  return minval     if newval  gt  maxval  return maxval     return newval   then just call it with something like   val   addInRange val  7  0  42    Or a simpler  more flexible  solution where you do the calculation yourself   def restrict val  minval  maxval       if val  lt  minval  return minval     if val  gt  maxval  return maxval     return val  x   restrict x 10  0  42    If you wanted to  you could even make the min max a list so it looks more  mathematically pure    x   restrict val 7   0  42

User · Answer

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  lt  l else u if x  gt  u else x      gt  gt  gt  import random  gt  gt  gt  rrange   random randrange  gt  gt  gt   timeit mm clip rrange 100   10  90  1000000 loops  best of 3  1 02   s per loop   gt  gt  gt   timeit s clip rrange 100   10  90  1000000 loops  best of 3  1 21   s per loop   gt  gt  gt   timeit np clip rrange 100   10  90  100000 loops  best of 3  6 12   s per loop   gt  gt  gt   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

User · Answer

sorted  minval  value  maxval   1    for example    gt  gt  gt  minval 3  gt  gt  gt  maxval 7  gt  gt  gt  for value in range 10         print sorted  minval  value  maxval   1       3 3 3 3 4 5 6 7 7 7

User · Answer

This one seems more pythonic to me    gt  gt  gt  def clip val  min   max            return min  if val  lt  min  else max  if val  gt  max  else val   A few tests    gt  gt  gt  clip 5  2  7  5  gt  gt  gt  clip 1  2  7  2  gt  gt  gt  clip 8  2  7  7

User · Answer

See numpy clip   index   numpy clip index  0  len my list  - 1

User · Answer

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

User · Answer

If your code seems too unwieldy  a function might help   def clamp minvalue  value  maxvalue       return max minvalue  min value  maxvalue    new index   clamp 0  new index  len mylist -1

[python] How to clamp an integer to some range?

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