python partial with keyword arguments

You may obtain the equivalent result you expect without using partial:

def foo(x =1, y = 2, z = 3):
    print 'x:%d, y:%d, z:%d'%(x, y, z)


if __name__ == '__main__':
    f1 = lambda z: foo(x=0, y=-6, z=z)
    zz = range(10)
    res = map(f1, zz)

Please see this link to have a better understanding: functools.partial wants to use a positional argument as a keyword argument

map(f1, zz) tries to call the function f1 on every element in zz, but it doesn't know with which arguments to do it. partial redefined foo with x=0 but map will try to reassign x because it uses positional arguments.

To counter this you can either use a simple list comprehension as in @mic4ael's answer, or define a lambda inside the map:

res = map(lambda z: f1(z=z), zz)

Another solution would be to change the order of the arguments in the function's signature:

def foo(z=3, x=1, y=2):