- Ever since Python 1.4, the slicing syntax has supported an optional third step or stride argument.
Syntax:
Listname[startindex:endindex:step]Other valid syntax are
- start list from 0 index
#start index field leave it blank
Listname[:endindex:step]- Here start from 0 indexes and end at last element with a given step
#start index and end index leave it blank
Listname[::step]- here start from start index and end at last element with the given step
# end index leave it blank
Listname[startindex::step]- s[i:j:k] is "slice of s from i to j with step k". When i and are absent, the whole sequence is assumed and thus s[::k] means "every k-th item".
Examples:
How to print 2,4,6
lists=[0,1,2,3,4,5,6,7,8,9]
start=2
end=8
step=2
result=lists[start:end:step]
print(result)
#Result : [2,4,6]output:
[2, 4, 6]
-
lists[::n] is a sequence of each n-th item in the entire sequence.
-
[::3] just means that you have not specified any start or end indices for your slice. Since you have specified a step, 3, this will take every third entry of something starting at the first index. For example:
lists=[0,1,2,3,4,5,6,7,8,9]
result=lists[::3]
print(result) Output:
[0, 6,9]
Let's take every 3rd item from second position list
lists=[0,1,2,3,4,5,6,7,8,9]
result=lists[2::3]
print(result) Output:
[2,5,8]