Saving a python list into a file.

B4RR13N705 · 2009-07-12 00:43:38

Hi, i was wondering one thing:
how to save a python list into a file.
For example, i have:

mylist = [1, 2 ,6 ,56, 78]

And i want to save them on a text file so the text file looks like this:

I mean, every value below the other.
I tried some stuff like

f = open("myfile", "w")
f.write(mylist)

But it save it as one long string and not one below the other.

BetterLeftUnsaid · 2009-07-12 01:09:03

f = open("myfile", "w")
mylist = [1, 2 ,6 ,56, 78]
f.write("\n".join(map(lambda x: str(x), mylist)))
f.close()

The above converts all the items in mylist to a string, and then joins them with the newline character before writing to the file. It doesn't have a trailing newline, though, so if you want the file to end with a newline:

f.write("\n".join(map(lambda x: str(x), mylist)) + "\n")

Use that instead.

Last edited by BetterLeftUnsaid (2009-07-12 01:09:37)

marxav · 2009-07-12 01:24:53

Or something like:
>>> for i in mylist:
... f.write(str(i)+'\n')

Dusty · 2009-07-12 02:03:14

BetterLeftUnsaid wrote:

f = open("myfile", "w")
mylist = [1, 2 ,6 ,56, 78]
f.write("\n".join(map(lambda x: str(x), mylist)))
f.close()

Map is kind of "unofficially deprecated" (along with filter and reduce); use generator expressions instead:

f.write("\n".join(str(x) for x in mylist))

Dusty

BetterLeftUnsaid · 2009-07-12 02:06:23

Dusty wrote:

Map is kind of "unofficially deprecated" (along with filter and reduce); use generator expressions instead:
f.write("\n".join(str(x) for x in mylist))
Dusty

I was kind of thinking that when I wrote it, but I wasn't too sure.

Curse my tendency to overly complicate things =/

B4RR13N705 · 2009-07-12 02:46:34

BetterLeftUnsaid wrote:

f = open("myfile", "w")
mylist = [1, 2 ,6 ,56, 78]
f.write("\n".join(map(lambda x: str(x), mylist)))
f.close()

This works perfectly! thanx!

Arch Linux

#1 2009-07-12 00:43:38

Saving a python list into a file.

#2 2009-07-12 01:09:03

Re: Saving a python list into a file.

#3 2009-07-12 01:24:53

Re: Saving a python list into a file.

#4 2009-07-12 02:03:14

Re: Saving a python list into a file.

#5 2009-07-12 02:06:23

Re: Saving a python list into a file.

#6 2009-07-12 02:46:34

Re: Saving a python list into a file.

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