How to let Pool.map take a lambda function
Use a function object:
class Copier(object): def __init__(self, tgtdir): self.target_dir = tgtdir def __call__(self, src): copy_file(src, self.target_dir)To run your Pool.map:
p.map(Copier(target_dir), file_list)
For Python2.7+ or Python3, you could use functools.partial:
import functoolscopier = functools.partial(copy_file, target_dir=target_dir)p.map(copier, file_list)
Question is a bit old but if you are still use Python 2 my answer can be useful.
Trick is to use part of pathos project: multiprocess fork of multiprocessing. It get rid of annoying limitation of original multiprocess.
Installation: pip install multiprocess
Usage:
>>> from multiprocess import Pool>>> p = Pool(4)>>> print p.map(lambda x: (lambda y:y**2)(x) + x, xrange(10))[0, 2, 6, 12, 20, 30, 42, 56, 72, 90]