Run a loop to generate variable names in Python [duplicate]

Question

I'm trying to import datasets which have the following filenames (phone1, phone2, etc)

df1 = pd.read_csv(r'C:\Users\...\phone1.csv')
df2 = pd.read_csv(r'C:\Users\...\phone2.csv')
df3 = pd.read_csv(r'C:\Users\...\phone3.csv')
df4 = pd.read_csv(r'C:\Users\...\phone4.csv')
df5 = pd.read_csv(r'C:\Users\...\phone5.csv')
df6 = pd.read_csv(r'C:\Users\...\phone6.csv')

I tried the following code

for i in range(1, 7):
    'df'+i = pd.read_csv(r'C:\Users\siddhn\Desktop\phone'+str(i)+'.csv', engine = 'python')

But I get an error saying that cannot assign to operator

How to import the datasets using a loop.?

Don't do that. Instead, create a list dfs = [] and use dfs.append( pd.read_csv(...) ). Now, you can use dfs[0] to refer to one specifically, but you can loop through them easily using for df in dfs:. — Tim Roberts
– Tim Roberts, Commented Jun 19, 2021 at 4:54
As @TimRoberts mentioned you can store your DataFrames in list, but if it essential for your DataFrames to have specific names, using dict in a loop also possible. Something like that could be made (inside your for loop): dfs[f"df_{i}"] = pd.read_csv(...) — Antonio Margaretti
– Antonio Margaretti, Commented Jun 19, 2021 at 4:58

Corralien · Accepted Answer · 2021-06-19 05:22:38Z

2

As @TimRoberts mentioned, you should use a list or a dictto store your dataframes but if you really want to have variable df1, df2, ..., df6, you can use locals() or globals():

for i in range(1, 7):
    locals()[f'df{i}'] = pd.read_csv(fr'C:\Users\siddhn\Desktop\phone{i}.csv')

print(df1)
print(df2)

edited Jun 19, 2021 at 5:22

answered Jun 19, 2021 at 5:09

Corralien

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2 Comments

Vishnudev Krishnadas Over a year ago

While using locals() may solve your problem, it will make your code messy and difficult to comprehend.

Corralien Over a year ago

@Vishnudev. I'm totally agree with you

Vishnudev Krishnadas · Accepted Answer · 2021-06-27 05:03:50Z

1

Use the inbuilt glob package

from glob import glob

fullpath = f'C:\Users\siddhn\Desktop\phone[1-6].csv'
dfs = [pd.read_csv(file) for file in glob(fullpath)]

print(dfs[0])

edited Jun 27, 2021 at 5:03

answered Jun 19, 2021 at 5:23

Vishnudev Krishnadas

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Comments

cbrr09 · Accepted Answer · 2021-06-19 05:13:33Z

1

you can store it in a list, here is the idea

var = []
for i in range(1, 7):
    var.append(i)

print(var[0])
print(var[2])

and from the list you can access the value using their key.

edited Jun 19, 2021 at 5:13

answered Jun 19, 2021 at 5:05

cbrr09

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Comments

pendela neelesh · Accepted Answer · 2021-06-19 05:02:45Z

'df'+i return a lvalue, i.e that can be assigned to other variables but cannot store some contents. insted of using

for i in range(1, 7):
    'df'+i = pd.read_csv(r'C:\Users\siddhn\Desktop\phone'+str(i)+'.csv', engine = 'python')

create a List of data_frames as df = [] Now append your data_frames as

for i in range(7):
   df.append(pd.read_csv(r'C:\Users\siddhn\Desktop\phone'+str(i)+'.csv', engine = 'python')

You can then acess data_frames by indexing them like df[0] or df[1].....

Felix K Jose · Accepted Answer · 2021-06-19 05:08:07Z

0

You can create a list of data frames and then iterate over it or access by index.

df_list = [pd.read_csv(r'C:\Users\siddhn\Desktop\phone'+str(i)+'.csv', engine = 'python') for i in range(1, 7)]
df_list[1]

The variable cannot be an operator thats the reason you get the error.

answered Jun 19, 2021 at 5:08

Felix K Jose

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