Writing a dictionary to a text file?

Question

I have a dictionary and am trying to write it to a file.

exDict = {1:1, 2:2, 3:3}
with open('file.txt', 'r') as file:
    file.write(exDict)

I then have the error

file.write(exDict)
TypeError: must be str, not dict

So I fixed that error but another error came

exDict = {111:111, 222:222}
with open('file.txt', 'r') as file:
    file.write(str(exDict))

The error:

file.write(str(exDict))
io.UnsupportedOperation: not writable

How do I resolve this issue?

hspandher · Accepted Answer · 2022-11-22T15:31:21.067

220

First of all you are opening file in read mode and trying to write into it. Consult - IO modes python

Secondly, you can only write a string or bytes to a file. If you want to write a dictionary object, you either need to convert it into string or serialize it.

import json

# as requested in comment
exDict = {'exDict': exDict}

with open('file.txt', 'w') as file:
     file.write(json.dumps(exDict)) # use `json.loads` to do the reverse

In case of serialization

import cPickle as pickle

with open('file.txt', 'w') as file:
     file.write(pickle.dumps(exDict)) # use `pickle.loads` to do the reverse

For python 3.x pickle package import would be different

import _pickle as pickle

edited Nov 22 '22 at 15:31

answered May 01 '16 at 10:22

hspandher

15,934
2
32
45

after opening the file, .close() is not needed here? – DatamineR Aug 31 '23 at 08:41
@DatamineR not needed if used as a context manager - https://book.pythontips.com/en/latest/context_managers.html#context-managers – hspandher Aug 31 '23 at 16:57

score 92 · Answer 2 · answered Nov 20 '18 at 09:22

92

I do it like this in python 3:

with open('myfile.txt', 'w') as f:
    print(mydictionary, file=f)

answered Nov 20 '18 at 09:22

NKSHELL

1,069
8
8

If your dict is not just regular string/numbers data put contains sets/list etc. as values and you want to print the dict to a text file, this is the way to go. – Bikash Gyawali Jun 20 '23 at 10:36

score 31 · Answer 3 · edited Sep 10 '17 at 07:57

31

fout = "/your/outfile/here.txt"
fo = open(fout, "w")

for k, v in yourDictionary.items():
    fo.write(str(k) + ' >>> '+ str(v) + '\n\n')

fo.close()

edited Sep 10 '17 at 07:57

MaNKuR

2,578
1
19
31

answered Sep 10 '17 at 06:07

Sange Negru

327
3
2

16

Code-only answers are discouraged because they do not explain how they resolve the issue. Please update your answer to explain how this improves on the other accepted and upvoted answers this question already has. Please review [How do I write a good answer](https://stackoverflow.com/help/how-to-answer). – FluffyKitten Sep 10 '17 at 07:59
1

Also, you should use the `with` statement when reading from and writing to files: https://stackoverflow.com/questions/3012488/what-is-the-python-with-statement-designed-for – Falko Jan 15 '18 at 17:58

score 19 · Answer 4 · edited May 18 '18 at 21:14

19

The probelm with your first code block was that you were opening the file as 'r' even though you wanted to write to it using 'w'

with open('/Users/your/path/foo','w') as data:
    data.write(str(dictionary))

edited May 18 '18 at 21:14

Erty Seidohl

4,487
3
33
45

answered May 18 '18 at 21:10

clyde_the_frog

199
1
2

score 11 · Answer 5 · answered Sep 11 '18 at 08:50

If you want a dictionary you can import from a file by name, and also that adds entries that are nicely sorted, and contains strings you want to preserve, you can try this:

data = {'A': 'a', 'B': 'b', }

with open('file.py','w') as file:
    file.write("dictionary_name = { \n")
    for k in sorted (data.keys()):
        file.write("'%s':'%s', \n" % (k, data[k]))
    file.write("}")

Then to import:

from file import dictionary_name

score 6 · Answer 6 · answered Apr 30 '20 at 10:39

For list comprehension lovers, this will write all the key : value pairs in new lines in dog.txt

my_dict = {'foo': [1,2], 'bar':[3,4]}

# create list of strings
list_of_strings = [ f'{key} : {my_dict[key]}' for key in my_dict ]

# write string one by one adding newline
with open('dog.txt', 'w') as my_file:
    [ my_file.write(f'{st}\n') for st in list_of_strings ]

score 2 · Answer 7 · answered Aug 14 '18 at 21:12

I know this is an old question but I also thought to share a solution that doesn't involve json. I don't personally quite like json because it doesn't allow to easily append data. If your starting point is a dictionary, you could first convert it to a dataframe and then append it to your txt file:

import pandas as pd
one_line_dict = exDict = {1:1, 2:2, 3:3}
df = pd.DataFrame.from_dict([one_line_dict])
df.to_csv('file.txt', header=False, index=True, mode='a')

I hope this could help.

score 1 · Answer 8 · answered Sep 04 '20 at 16:03

1

exDict = {1:1, 2:2, 3:3}
with open('file.txt', 'w+') as file:
    file.write(str(exDict))

answered Sep 04 '20 at 16:03

ianzo

11
1

score 0 · Answer 9 · edited Oct 16 '19 at 20:20

0

You can do as follow :

import json
exDict = {1:1, 2:2, 3:3}
file.write(json.dumps(exDict))

https://developer.rhino3d.com/guides/rhinopython/python-xml-json/

edited Oct 16 '19 at 20:20

LaSul

2,231
1
20
36

answered Sep 02 '18 at 05:35

Shivam Verma

1
1

score 0 · Answer 10 · answered Sep 12 '22 at 09:23

In my case, I have to write the dictionary in a file but in YAML format. I found this question here helpful but the answers were only in JSON or String. Hence I'm adding my exploration here - so that it may help others for YAML format.

import yaml

my_dictionary = {
    "numbers": ["one", "two", "three"],
    "colours": ["blue", "pink"],
    "name": "Santosh"
}

with open("test.yaml", "w") as file:
    file.write(yaml.dump(my_dictionary))

Output in test.yaml file is,

colours:
- blue
- pink
name: Santosh
numbers:
- one
- two
- three

Hope this helps!

score -2 · Answer 11 · answered May 09 '19 at 01:47

-2

import json

with open('tokenler.json', 'w') as file:
     file.write(json.dumps(mydict, ensure_ascii=False))

answered May 09 '19 at 01:47

Mehmet Ali Bayram

7,222
2
22
27

You could improve this error by adding an explanation of why it works. – Greg the Incredulous May 09 '19 at 02:06

Writing a dictionary to a text file?

11 Answers11

Linked

Related