Saving multiple dataframes to CSV using loop in python

Question

I am trying to save multiple dataframes to csv in a loop using pandas, while keeping the name of the dataframe.

import pandas as pd
 
df1 = pd.DataFrame({'Col1':range(1,5), 'Col2':range(6,10)})
df2 = pd.DataFrame({'Col1':range(1,5), 'Col2':range(11,15)})

frames = [df1,df2]

for data in frames:
    data['New'] = data['Col1']+data['Col2']
    
for data in frames:
    data.to_csv('C:/Users/User/Desktop/{}.csv'.format(data))

This doesn't work, but the outcome I am looking for is for both dataframes to be saved in CSV format, to my desktop.

df1.csv
df2.csv

Thanks.

Which version of Python are you using?

DisappointedByUnaccountableMod
– DisappointedByUnaccountableMod

2021-09-25 21:14:42 +00:00
Commented Sep 25, 2021 at 21:14 — DisappointedByUnaccountableMod
– DisappointedByUnaccountableMod, Commented Sep 25, 2021 at 21:14

Anwarvic · Accepted Answer · 2021-09-25 21:04:06Z

5

You just need to set the names of the CSV files; like so:

names = ["df1", "df2"]
for name, data in zip(names, frames):
    data.to_csv('C:/Users/User/Desktop/{}.csv'.format(name))

answered Sep 25, 2021 at 21:04

Anwarvic

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6 Comments

DisappointedByUnaccountableMod Over a year ago

Or using an f-string: data.to_csv(f'C:/Users/User/Desktop/{name}.csv')

Anwarvic Over a year ago

yeah sure, but this won't work if he uses python 3.4 for example

DisappointedByUnaccountableMod Over a year ago

Or in Python 2.7, if you want to choose a random Python version older than 3.9?

Jack Over a year ago

Thank you, has solved this issue.

Anwarvic Over a year ago

@balmy haha, true!! I just wanted to point out that this feature was added in only python 3.5... any version before that won't work

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TroyMcClure8998 · Accepted Answer · 2021-09-25 21:03:50Z

0

Hope this help. Note I did not use the format function. But I set up code in the directory I am working on.

import pandas as pd
 
df1 = pd.DataFrame({'Col1':range(1,5), 'Col2':range(6,10)})
df2 = pd.DataFrame({'Col1':range(1,5), 'Col2':range(11,15)})

frames = [df1,df2]

for data in frames:
    data['New'] = data['Col1']+data['Col2']
  
n = 0
for data in frames:
    n = n + 1
    data.to_csv('df' + str(n) + ".csv")

answered Sep 25, 2021 at 21:03

TroyMcClure8998

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1 Comment

TroyMcClure8998 Over a year ago

np. Now it will be saved as df1.csv, df2.csv.... if you want it to be "Jack" change it to data.to_csv('Jack' + str(n) + ".csv") in the loop area.

D.Manasreh · Accepted Answer · 2021-09-25 21:17:05Z

0

In this loop:

for data in frames:
    data.to_csv('C:/Users/User/Desktop/{}.csv'.format(data))

You are looping over a list of DataFrame objects so you cannot use them in a string format.

Instead you could use enumerate() to get the indexes as well as the objects. Then you can use the indexes to format the string.

for idx,data in enumerate(frames):
    data.to_csv('df{}.csv'.format(idx + 1)) 
# the reason for adding 1 is to get the numbers to start from 1 instead of 0

Otherwise you can loop through your list just using the index like this:

for i in range(len(frames)):
    frames[i].to_csv('df{}.csv'.format(idx + 1))

answered Sep 25, 2021 at 21:17

D.Manasreh

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