Python字典以必需格式转换为CSV

Question

I have a python dictionary that looks like the following:

{
  key1: [value1, value2, value3, n],
  key2: [value1, value2, value3, n],
  key3: [value1, value2, value3, n],
  key4: [value1, value2, value3, n]
}

I would like to write these values to a csv file in the format where each line contains Keys as header and associated values(row by row) under that key.

Answer 1

pandas provides a very straight forward solution to the problem -

import pandas as pd 
df = pd.DataFrame({
  'key1': ['value1', 'value2', 'value3', 'n'],
  'key2': ['value1', 'value2', 'value3', 'n'],
  'key3': ['value1', 'value2', 'value3', 'n'],
  'key4': ['value1', 'value2', 'value3', 'n']
})
df.to_csv('/path/to/file')

Answer 2

Perhaps pandas can provide you with a more direct way of achieving this, but if you simply want to rely on the csv package from the standard library, the following naive approach should do:

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import csv


data = {
    'key1': ['value1', 'value2', 'value3', 'n'],
    'key2': ['value1', 'value2', 'value3', 'n'],
    'key3': ['value1', 'value2', 'value3', 'n'],
    'key4': ['value1', 'value2', 'value3', 'n']
}

header = data.keys()
no_rows = len(data[list(header)[0]])

with open('out.csv', 'w', newline='') as csvfile:
    csvwriter = csv.writer(csvfile, delimiter=',')
    csvwriter.writerow(header)
    for row in range(no_rows):
        csvwriter.writerow([data[key][row] for key in header])

This results in

key1,key2,key3,key4
value1,value1,value1,value1
value2,value2,value2,value2
value3,value3,value3,value3
n,n,n,n

Hope this helps!

EDIT

Since this is now the accepted answer, I feel that I should add that pandas.DataFrame.to_csv does indeed provide a more direct way of achieving this, as mentioned in other answers:

import pandas as pd

pd.DataFrame(data).to_csv('out.csv', index=False)

produces the same output as above (possibly with different line terminators, depending on your system).