Here is the loop I am trying to use the map function on:
volume_ids = [1,2,3,4,5]
ip = '172.12.13.122'
for volume_id in volume_ids:
my_function(volume_id, ip=ip)
Is there a way I can do this? It would be trivial if it weren't for the ip parameter, but I'm not sure how to deal with that.
Use functools.partial():
from functools import partial
mapfunc = partial(my_function, ip=ip)
map(mapfunc, volume_ids)
partial() creates a new callable, that'll apply any arguments (including keyword arguments) to the wrapped function in addition to whatever is being passed to that new callable.
Here is a lambda approach (not better, just different)
volume_ids = [1,2,3,4,5]
ip = '172.12.13.122'
map(lambda ids: my_function(ids, ip), volume_ids);
This can be done easily with a list comprehension.
volume_ids = [1,2,3,4,5]
ip = '172.12.13.122'
results = [my_function(i,ip=ip) for i in volume_ids]
In general, one can use map to pass keywords to a function by wrapping that function in something which unpacks a dictionary, and then passing an iterable of dictionaries to map. Example:
from itertools import product
volume_ids = [1,2,3,4,5]
volume_ids = (("volume_id", volume_id) for volume_id in volume_ids)
ips = [("ip", '172.12.13.122')]
kwargs_iterable = map(dict, product(volume_ids, ips))
result = map(lambda kwargs: my_function(**kwargs), kwargs_iterable)
For your special case, however, a simpler solution would be:
map(my_function, volume_ids, [ip]*len(volume_ids))
This is concise and does not rely on any imports. Another possibility could be to combine product and starmap from itertools:
from itertools import product, starmap
ips = [ip]
starmap(my_function, product(volume_ids, ips))
This generalizes nicely to the setting with more than one ip adress, or more than two variables.
How about this?
results = []
for volume_id in volume_ids:
results.append(my_function(volume_id, ip=ip))
This is three lines of code instead of one --- it's three lines of clear and obvious code instead of importing some special-case helper from module such-and-such. This argument is probably a matter of taste, but it has a lot of weight depending on who you talk to.
