write dictionary of lists to a tab delimited file in python, with dictionary key values as columns without Pandas

Question

the dictionary I am using is:

dict={'item': [1,2,3], 'id':['a','b','c'], 'car':['sedan','truck','moped'], 'color': ['r','b','g'], 'speed': [2,4,10]}

I am trying to produce a tab delimited out put as such:

item    id
1       a
2       b
3       c

The code I have written:

with open('file.txt', 'w') as tab_file:
    dict_writer = DictWriter(tab_file, dict.keys(), delimiter = '\t')
    dict_writer.writeheader()
    dict_writer.writerows(dict)

specifically, I am struggling with writing to the file in a column based manner. Meaning, that the dictionary keys populate as the header, and the dictionary values populate vertically underneath the associated header. Also, I do NOT have the luxury of using Pandas

Answer 1

This solution will work for an ambiguous number of items and subitems in the dict:

d = {'item': [1, 2, 3], 'id': [4, 5, 6]}

for i in d:
    print(i + "\t", end="")
    numSubItems = len(d[i])
print()


for level in range(numSubItems):
    for i in d:
        print(str(d[i][level]) + "\t", end="")
    print()

EDIT: To implement this with writing to a text file:

d = {'item': [1, 2, 3], 'id': [4, 5, 6], 'test': [6, 7, 8]}


with open('file.txt', 'w') as f:
    for i in d:
        f.write(i + "\t")
        numSubItems = len(d[i])
    f.write("\n")

    for level in range(numSubItems):
        for i in d:
            f.write(str(d[i][level]) + "\t")
        f.write("\n")

Answer 2

Here's a way to do this using a one-off function and zip :

d = {
    'item': [1, 2, 3],
    'id': ['a', 'b', 'c'],
    'car': ['sedan', 'truck', 'moped'],
    'color': ['r', 'b', 'g'],
    'speed': [2, 4, 10],
    }

def row_printer(row):
    print(*row, sep='\t')

row_printer(d.keys())  # Print header
for t in zip(*d.values()):  # Print rows
    row_printer(t)

To print to a file: print(..., file='file.txt')

Answer 3

You can use a simple loop with a zip :

d={'item': [1,2,3], 'id':["a","b","c"]}

print('item\tid')
for num, letter in zip(d['item'], d['id']):
    print('\t'.join(str(num) + letter))

item    id
1       a
2       b
3       c

EDIT:
If you don't want to hard code column names you can use this:

d={'item': [1,2,3], 'id':["a","b","c"]}

print('\t'.join(d.keys()))
for num, letter in zip(*d.values()):
    print('\t'.join(str(num) + letter))

However the order of the columns is only guaranteed in python3.7+ if you use a dictionary. If you have a lower python version use an orderedDict instead, like this:

from collections import OrderedDict

d=OrderedDict({'item': [1,2,3], 'id':["a","b","c"]})

print('\t'.join(d.keys()))
for num, letter in zip(*d.values()):
    print('\t'.join(str(num) + letter))

Answer 4

Instead of using csv.DictWriter you can also use a module like pandas for this:

import pandas as pd

df = pd.DataFrame.from_dict(d)
df.to_csv(“test.csv”, sep=“\t”, index=False)

Probably, you have to install it first by using

pip3 install pandas

See here for an example.