Python Dictionary to CSV

Question

I have written code to read a CSV into a python dictionary, which works fine. I\'m trying to get the dictionary back to a CSV. I have written the following:

Answer 1

For posterity:

You should use iteritems() to iterate over a dictionary, so the last part becomes

for name, values in itemDict.iteritems():
    print values
    listWriter.writerow(values)

Answer 2

Easiest Way

You can convert the dictionary into Dataframe and write it to csv Eg

import pandas as pd
my_dict = {"tester": 1, "testers": 2}
df=pd.DataFrame(my_dict,index=[0])
df.to_csv("path and name of your csv.csv")

output

   tester  testers
0       1        2

Answer 3

The default writer expects a list, which is why it won't work for you. To use the dictwriter, just change your listwriter = line to this:

with open('/Users/broberts/Desktop/Sum_CSP1_output.csv', 'wb') as outfile:
    listWriter = csv.DictWriter(
       outfile,
       fieldnames=itemDict[itemDict.keys()[0]].keys(),
       delimiter=',',
       quotechar='|',
       quoting=csv.QUOTE_MINIMAL
    )

Or, you can just set fieldnames to be fieldnames=['arbitrary','list','of','keys'] if you know what the fields are supposed to be.

Answer 4

d = [{'a': 1, 'b': 2},{'a': 3, 'b': 4}]

with open('csv_file.csv', 'w', newline='\n') as f:
    w = csv.DictWriter(f, d[0].keys())
    w.writeheader()
    for i in d:
        w.writerow(i)

gets you

a,b
1,2
3,4

Answer 5

Sample data:

mydict = [{"col1": 1000, "col2": 2000}, {"col1": 3000, "col2": 4000}]

One-liner for converting a list of dicts to CSV, using pandas:

import pandas as pd

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

Results:

col1,col2
1000,2000
3000,4000

Answer 6

This is what i use, its simple and works fine for me. when you have only one dictionary, use this

my_dict = {"tester": 1, "testers": 2}
with open('mycsvfile.csv', 'wb') as f:  
    w = csv.DictWriter(f, my_dict.keys())
    w.writerow(dict((fn,fn) for fn in my_dict.keys()))
    w.writerow(my_dict)

$ cat mycsvfile.csv
testers,tester
2,1

When you have a list of dictionaries, like what you get from SQL queries, you do like this.

my_dict = ({"tester": 1, "testers": 2},{"tester": 14, "testers": 28})
with open('mycsvfile.csv', 'wb') as f:  
    w = csv.DictWriter(f, my_dict[0].keys())
    w.writerow(dict((fn,fn) for fn in my_dict[0].keys()))
    w.writerows(my_dict)

cat mycsvfile.csv
testers,tester
2,1
28,14