Does someone know the difference between these two and why? lambda doesn't not allow to reverse a single string?
s = ['justdoit','asdf']
list(map(lambda s: s[::-1], s))
s = 'justdoit'
list(map(lambda s: s[::-1], s))
It is applying the slicer, but because a string is iterable, it's being applied to each single letter of s, and the reversal of a single-letter string is just the single letter.
For example:
>>> map(lambda x: print(x), 'justdoit')
>>> list(map(lambda x: print(x), 'justdoit'))
j
u
s
t
d
o
i
t
[None, None, None, None, None, None, None, None]
and so
>>> s = 'justdoit'
>>> list(map(lambda s: s[::-1], s))
['j', 'u', 's', 't', 'd', 'o', 'i', 't'] # 'j' reversed, 'u' reversed, etc
I think this boils down to how python/lambda interprets strings and arrays. When you pass a single string in your 2nd attempt, the lambda takes it in as an array of characters. Where as in the first attempt, it receives it as an array of string objects to work on. If you want to reverse even a single string, you will need to pass it as an array of single string.
Eg.
s = ['justdoit']
list(map(lambda s: s[::-1], s))
This should work
