函数返回中的map与list理解

Question

Simple question:

Matplotlib has a function that returns two values:

locs,label = plt.yticks()

Pylint complains about this line, telling me "Used builtin function map". So I went to pylint site and found this: http://pylint-messages.wikidot.com/messages:w0141 So, I'm trying to fix this warning using list comprehension. But what is the correct form?

[(locs,label) for plt.yticks()]

is not working.

Thanks!

EDIT: I made a simple test script to try to show the problem, and the problem was one line below:

#!/usr/bin/python

""" docstring """

import matplotlib.pyplot as plt

LOCS, LABEL = plt.yticks()

plt.yticks(LOCS, map(lambda x: "%.2f" % x, LOCS)) # offending line

print(LOCS)

So duh, I was looking on the wrong line. How this lambda can be adjusted to list comprehension? Thanks

Answer 1

locs,label = plt.yticks()

Is the correct way to receive two variables from a function. You could receive it as a single variable, and work with the tuple object, but that would be pointless.

It's possible that pylint is complaining about plt.yticks . Apart from it being out of your control, it is not in general preferable to use a list comprehension instead of map , just in a wide variety of cases.

In the case of plt.yticks(LOCS, map(lambda x: "%.2f" % x, LOCS)) , a list comprehension is likely to be more readable, and may be faster.