Hi,
I'd agree with the advice that it's not the best idea: readability sucks
here, but consider the following:
import time
def somefunc(a,b,c,d): # dummy function
return "{} - {} - {} : {}".format(a,b,c,d)
l = [(time.time(),"name {}".format(n)) for n in range(100)] # dummy data
# the line in question
labels = [somefunc(*(lambda t,n:
(t.tm_mon,t.tm_mday,t.tm_wday,n))(time.localtime(x[0]),x[1])) for x in l]
print(labels) # just to see the result
If you find that hard to decipher, the consider the maintainability of
code you write that uses such comprehensions. You need to include
comments that explain what this does, and it is easier to write a
longhand version using .append() and variable assignments. I presume
performance won't be an issue determining the right approach, since then
you'd be using C or C++.
John
On 17/01/2014 23:49, Dan Stromberg wrote:
On Fri, Jan 17, 2014 at 3:19 PM, Piet van Oostrum <p...@vanoostrum.org> wrote:
Hi,
I am looking for an elegant way to write the following code as a list
comprehension:
labels = []
for then, name in mylist:
_, mn, dy, _, _, _, wd, _, _ = localtime(then)
labels.append(somefunc(mn, day, wd, name))
My recomendation: Don't use a list comprehension. List comprehensions
and generator expressions are great for quick little things, but
become less readable when you have to string them over multiple
physical lines.
labels = [somefunc(mn, day, wd, name)
for then, name in mylist
for _, mn, dy, _, _, _, wd, _, _ in [localtime(then)]]
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