python - How can I use colon (:) in variable -
this question has answer here:
i want write code this:
index = 0:2 print(list[index]) but not work.
is there way can store parts of [...:...] syntax in variable?
you want slice() object:
index = slice(0, 2) print(somelist[index]) slice() models start, stop , stride values can specify in [start:stop:stride] subscription syntax, object.
from documentation:
return slice object representing set of indices specified
range(start, stop, step). start , step arguments defaultnone. slice objects have read-only data attributesstart,stop,stepmerely return argument values (or default).
under covers, python translates subscriptions slice() object when calling custom __getitem__ methods:
>>> class foo(object): ... def __getitem__(self, item): ... return item ... >>> foo()[42:81:7] slice(42, 81, 7) >>> foo()[:42] slice(none, 42, none) a viable alternative store start , stop separate values:
startindex = 0 stopindex = 2 print(somelist[start:stop])
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