Writing a nested dictionary to a .txt file

Question

I have a dictionary that looks like this

{'Berlin': {'Type1': 96},
 'Frankfurt': {'Type1': 48},
 'London': {'Type1': 288, 'Type2': 64, 'Type3': 426},
 'Paris': {'Type1': 48, 'Type2': 96}}

I then want to write to a .txt file in the format

London
  Type1: 288
  Type2: 64
  Type3: 426

Paris
  Type1: 48
  Type2: 96

Frankfurt
  Type1: 48

Berlin
  Type1: 98

I've tried to use

f = open("C:\\Users\\me\\Desktop\\capacity_report.txt", "w+")
f.write(json.dumps(mydict, indent=4, sort_keys=True))

but this prints like this:

{
    "London": {
        "Type1": 288,
        "Type2": 64,
        "Type3": 426
     },
     "Paris": {
         "Type1": 48,
         "Type2": 96
     },
     "Frankfurt": {
         "Type1": 48
      },
      "Berlin": {
         "Type1": 98
      }
}

I'd like to have the punctuation and brackets removed. Is there a way to do this I can't see?

Python version? I don't understand exactly what do you want, filter entries where key is '\n'? — Tzomas, Jan 19 '18 at 16:39
I've removed the `\n` key-value issue for now, as that's a separate question (although you can trivially test for values not equal to 0 in the inner loop). — Martijn Pieters, Jan 19 '18 at 16:47

Martijn Pieters · Accepted Answer · 2018-01-19T17:01:01.320

2

You'll need to write out your dictionary manually. You are not trying to produce JSON here, and there is no point in using that module.

Iterate over the dictionary keys and values and write those out as lines. The print() function can be helpful here:

from __future__ import print_function

with open("C:\\Users\\me\\Desktop\\capacity_report.txt", "w") as f:
    for key, nested in sorted(mydict.items()):
        print(key, file=f)
        for subkey, value in sorted(nested.items()):
            print('   {}: {}'.format(subkey, value), file=f)
        print(file=f)

The print() function takes care of newlines for us.

edited Jan 19 '18 at 17:01

answered Jan 19 '18 at 16:45

Martijn Pieters

1,048,767
296
4,058
3,343

Appreciate the reply, this throws this error: print(key, file=f) ^ SyntaxError: invalid syntax. Can't see anything obvious causing that – CEamonn Jan 19 '18 at 16:53
@CEamonn: maybe you are using the old Python 2? – cdarke Jan 19 '18 at 16:57
@cdarke apologies, I am using 2.7 – CEamonn Jan 19 '18 at 16:57
@CEamonn: that is easily remedied as you can enable the Python 3 syntax on a per module basis with a `__future__` import. – Martijn Pieters Jan 19 '18 at 17:02
@CEamonn: you can do this without the `__future__` import too: the Python 2 statement can also direct the output to a file, but with the import your code is now also Python 3 compatible. If you are new to Python I’d actually strongly recommend you learn Python 3 and not bother with Python 2. – Martijn Pieters Jan 19 '18 at 17:16
@CEamonn: the Python 2 only syntax is `print >> f, `. – Martijn Pieters Jan 19 '18 at 17:18
@MartijnPieters thanks a lot, sorted. I'll leave 2 and look into 3 – CEamonn Jan 19 '18 at 17:21

Tzomas · Answer 2 · 2018-01-19T17:52:36.463

0

If you use python 3.6 which preserve order on insert keys on dictionary, you can use something like this.

with open('filename.txt','w') as f:
    for city, values in my_dict.items():
        f.write(city + '\n')
        f.write("\n".join(["  {}: {}".format(value_key, digit) for value_key, digit in values.items()]) + '\n')
        f.write('\n')

Its works changing f.write for print. i hope this helps.

edited Jan 19 '18 at 17:52

answered Jan 19 '18 at 16:58

Tzomas

704
5
17

You are not writing enough newlines; remember that `print()` *adds* a newline each time that `file.write()` doesn’t. – Martijn Pieters Jan 19 '18 at 17:12
True, I forgot to put the two new lines. – Tzomas Jan 19 '18 at 17:31
There is also a blank line missing, between each `city` section. – Martijn Pieters Jan 19 '18 at 17:40

Writing a nested dictionary to a .txt file

2 Answers2