I have the following code:
a = '0'
b = '256'
mod_add = ['300', '129', '139']
list(map(lambda a, b, x: (a < x) and (x < b), a, b, mod_add))
I'd like to check every element in mod_add, but
list(map(lambda a, b, x: (a < x) and (x < b), a, b, mod_add))
returns only one False.
With some values (a = '100', b = '200') it returns 'False', 'False', 'False'.
What am I doing wrong?
If you really have to use map:
list(map(lambda x: (a < x) and (x < b), mod_add))
Edit:
In response to the desire to map only one element from the list, it really doesn't make such sense to me to do that. But if that's what you wish to do, you can try:
list(map(lambda x: (a < x) and (x < b), [mod_add[0]]))
I hope this helps.
>>> list(lambda x: (a < x) and (x < b), mod_add[0]) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: list() takes at most 1 argument (2 given) 
list(map(lambda x: (a < x) and (x < b), [mod_add[0]])).list(lambda x: (a < x) and (x < b), mod_add[0]), still I see error ' list() takes at most 1 argument (2 given)'. (I already changed a and b to integers (and mod_add to list of integers too))mod_add[0] with a and b then just do (a < mod_add[0]) and (mod_add[0] < b). You really don't need map() for that.a and b are strings, they will be rightly treated as iterables by map, not constants as you intend. You should either use a list comprehension or not pass a and b as parameters to map:
>>> [a < x < b for x in mod_add]
[False, True, True]
Comparisons can be chained arbitrarily, so (a < x) and (x < b) can be replaced with a < x < b
Comparing integers instead of strings (which is probably what you want) is just another step away:
>>> [int(a) < int(i) < int(b) for i in mod_add]
[False, True, True]
This is really the kind of thing you should prefer list comprehensions for.
min_, max_ = '0', '256'
# do you mean for these to be compared lexicographically?!
# be aware that '0' < '1234567890' < '256' is True
mod_add = ['300', '129', '139']
result = [min_ < mod < max_ for mod in mod_add]
# [False, True, True]
map filter and reduce (now functools.reduce) are mighty tools to be sure, but Python tends to shy away from them in favor of more verbose, easier to read expressions.
a = '0'
b = '256'
mod_add['300', '129', '139']
map(lambda x: int(a)<int(x)<int(b), mod_add)
Output :
[False, True, True]
