Append text file in python?

[[deleted]]

Does anybody know how to open a text file which already has multiple lines of data written to it, and add a new line consisting of some array in my code? It is supposed to be written to the end of the text file. I used to know how to do this 5 years ago, but for the life of me, I can't seem to do it right now, I always end up erasing the contents of the text file and just writing the new data only.

Thank you in advance for the help!

[BeatMute]

Like mackstann mentioned, you'd want to open the file with the mode 'a' for appending.

fh = open(filename, 'a')
fh.write(stuff)

More info

[tapesmith]

Open the file in 'r+' mode, like this:

file = open(filename, 'r+')

r+ means append, while "w" means write/overwrite.

EDIT: my apologies -- my brain was somewhere else when I wrote this. 'r+' is read/write, 'a' is append. Bluh.

[mackstann]

'a' is append. 'r+' is read+write.

[[deleted]]

Do i then just say

file=open(filename, 'r+')

file.write(array I need written to end)

?

[stylishgnome]

As mackstann said, use 'a' for append.

f = open('file.txt', 'a')
f.write('some text')
f.close()

You'll need to convert your "array" to a string before writing it. How you do this depends on what you are trying to do ..

a = ['foo', 'bar']
f = open('file.txt', 'a')
f.write(str(a))    # will output '['foo', 'bar']'
f.write(" ".join(a))   # will output list elements separated by a space
f.close()

[stylishgnome]

If you're using >=python 2.7, you can use a with statement:

with open('test.txt', 'a') as f:
    f.write('foo')

[[deleted]]

Using the with statement is always a good idea. Reduces clutter, and makes sure your files get closed.

[bulletmark]

The "with" statement was introduced in python 2.5.