How to run strings as a command in python

Question

I added two strings together and now I want to use those strings to create multiple dataframes.... I currently have:

filepath = 'C:/........GC results/lng_11169_fid00'

l = []

for i in range(1,7):
    newpath = filepath + str(i)
    l.append(newpath)

print l 



d =[]

for i in range(1,7):
    dataframes = "df" + str(i)
    d.append(dataframes)
print d
enter code here



m = []
dfstr = "pd.DataFrame.from_csv("

for i in d:
    for x in l:
        newdf =  i + "="+ dfstr + x + ", index_col = None)"
        m.append(newdf)
print m

out:

['df1=pd.DataFrame.from_csv(C:...lng_11169_fid001, index_col = None)', 'df2=pd.DataFrame.from_csv(C:...lng_11169_fid002, index_col = None)'..... + 20 others]

I want to use those strings to make a DataFrame. Is this possible?

@Trimax but this is about calling an internal Python command, isn't it? — SuperBiasedMan
– SuperBiasedMan, Commented Jun 10, 2015 at 9:39
@SuperBiasedMan You're all right. He wants to execute code dinamically. — Trimax
– Trimax, Commented Jun 10, 2015 at 9:47

Łukasz Rogalski · Accepted Answer · 2015-06-10 09:49:45Z

1

An XY problem... Is this what you want? Simply write executable code instead of string concatenation.

import glob
import pandas as pd
path_pattern = 'C:/........GC results/lng_11169_fid00*'
files = glob.glob(path_pattern)
dataframes = [pd.DataFrame.from_csv(f, index_col=None) for f in files]
print dataframes[0]  # yours df1

answered Jun 10, 2015 at 9:49

Łukasz Rogalski

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2 Comments

Joey Over a year ago

Will this find _fid_001 to _012? and then create a dataframe from each csv?

Joey Over a year ago

Yes it does.. Many thanks for this simple yet powerful answer!

farhawa · Accepted Answer · 2015-06-10 09:38:04Z

0

This should work

list_ = ['df1=pd.DataFrame.from_csv(C:...lng_11169_fid001, index_col = None)', 'df2=pd.DataFrame.from_csv(C:...lng_11169_fid002, index_col = None)'..... + 20 others]

for code_ in list_:
     exec code_

answered Jun 10, 2015 at 9:38

farhawa

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2 Comments

SuperBiasedMan Over a year ago

exec is a potentially dangerous command to call, I wouldn't just suggest someone use it without explaining what it does.

Anand S Kumar Over a year ago

This does not work in python3 either, you need to do - exec(code_)

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