How to write CSV from a list of dictionaries-CodePudding

I found a lot of posts about going from CSV to a list of dictionaries but not the other way around. I'm trying to write a csv file from a list of dictionaries, within each dictionary the keys are the same and there are equal number of pairings per dictionary. How would I go about using the keys for the header row?

edit: yes I've read the adam smith page with the DictWriter unfortunately, I don't know the key names ahead of time just that the names are the same across all dictionaries in the list.

ie. [{A:1,B:2},{A:3,B:4}] into...
A,B
1,2
3,4

import csv

def function(list_of_dic,csvFileName):
  with open(list_of_dic,'w') as f:
    writer = csv.DictWriter(f)

CodePudding user response：

import pandas as pd

data = [{'A': 5, 'B': 0, 'C': 3, 'D': 3},
        {'A': 7, 'B': 9, 'C': 3, 'D': 5},
        {'A': 2, 'B': 4, 'C': 7, 'D': 6}]

df = pd.DataFrame(data)
df = pd.DataFrame.from_dict(data)
df = pd.DataFrame.from_records(data)
df.to_csv("Filename.csv")

output:

 A  B  C  D
0  5  0  3  3
1  7  9  3  5
2  2  4  7  6

CodePudding user response：

The DictWriter doc has a good example. Assuming you know the key names in advance, you use those as the fieldnames. And since you already have a list of dicts, writerows will consume them all.

import csv

def function(list_of_dic,csvFileName):
  with open(list_of_dic,'w') as f:
    writer = csv.DictWriter(f, fieldnames=["A", "B", "C"])
    writer.writeheader()
    writer.writerows(list_of_dic)