python a simple way to get list subscripts and their values
- 2020-05-10 18:29:07
- OfStack
When traversing a sequence in python, we usually use the following method:
for item in sequence:
process(item)
If you want to get to an item location, you can write:
for index in range(len(sequence)):
process(sequence[index])
Another good way is to use python's built-in enumerate function:
enumerate(sequence,start=0)
In the above functions, sequence is an iterable object, which can be a list, dictionary, file object, and so on. enumerate returns a tuple of subscripts and item:
>>> seasons = ['Spring', 'Summer', 'Fall', 'Winter']
>>> list(enumerate(seasons)) [(0, 'Spring'), (1, 'Summer'), (2, 'Fall'), (3, 'Winter')]
>>> list(enumerate(seasons, start=1)) [(1, 'Spring'), (2, 'Summer'), (3, 'Fall'), (4, 'Winter')]
The first example of the article could then be written like this:
for index,item in enumerate(sequence):
print index,item