Generating multiple pandas data frames within a loop, with variable variable names

Question

I am trying to generate multiple pandas data frames within a loop, I am having difficulty with the variable definitions though. The first iteration of str(test[i-1]) returns A, so I assumed I could concatenate this string with another string to create a variable, the first variable should be defined as A_data_columns=['Test1','Test2'] however this throws an error (which I half expected), I was just wondering if there is a way to do this properly, or perhaps a better way?

test=[]
for i in range(1,5):
    test.append(chr(ord('@')+i))
    str(test[i-1])+'_data_columns'=['Test1', 'Test2']
    str(test[i-1])+'_dataframe'=pd.DataFrame(columns=str(test[i-1])+'_data_columns')
    str(test[i-1])+'_dataframe'

Error:

SyntaxError: cannot assign to operator

Akash Haridas · Accepted Answer · 2021-01-14 13:35:52Z

1

str(test[i-1])+'_data_columns' is a string, and not a variable name. You cannot assign a value to the string, it makes no sense.

One way to solve this would be to use a dictionary. In this way you can map a string to an object, which is what you are trying to do.

test=[]
test_dict = dict()
for i in range(1,5):
    test.append(chr(ord('@')+i))
    test_dict[str(test[i-1])+'_data_columns'] = ['Test1', 'Test2']
    test_dict[str(test[i-1])+'_dataframe'] = pd.DataFrame(columns=str(test[i-1])+'_data_columns')

You can then access the values as follows:

print(test_dict['A_data_columns'])
# should print ['Test1', 'Test2']

answered Jan 14, 2021 at 13:35

Akash Haridas

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