I find myself frequently writing code like this:
k = 0
for i in mylist:
# y[k] = some function of i
k += 1
Instead, I could do
for k in range(K):
# y[k] = some function of mylist[k]
but that doesn't seem "pythonic". (You know... indexing. Ick!) Is there some syntax that allows me to extract both the index (k) and the element (i) simultaneously using either a loop, list comprehension, or generator? The task is in scientific computing, so there is a lot of stuff in the loop body, making a list comprehension probably not powerful enough on its own, I think.
I welcome tips on related concepts, too, that I might not have even though of. Thank you.
You can use enumerate
:
for k,i in enumerate(mylist):
#do something with index k
#do something with element i
More information about looping techniques.
Edit:
As pointed out in the comments, using other variable names like
for i, item in enumerate(mylist):
makes it easier to read and understand your code in the long run. Normally you should use i
, j
, k
for numbers and meaningful variable names to describe elements of a list.
I.e. if you have e.g. a list of books and iterate over it, then you should name the variable book
.
enumerate
is the answer:
for index, element in enumerate(iterable):
#work with index and element
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