In[2]:  df1.std()
Out[2]:
  some_int      15281.99
  some_float    5.302293

In[3]:  df2.std()
Out[3]:
  some_int      15281.99
  some_float    6.691013

import pandas as pd
 import numpy as np

 data_list = list()
 csv_files = ['a.csv', 'b.csv', 'c.csv']

 for csv_file in csv_files:

    #  load csv_file
    tmp_df = pd.read_csv(str(tmp_file), index_col='ID', dtype=np.float64)

    # replace infs by na
    tmp_df.replace([np.inf, -np.inf], np.nan, inplace=True)

    # manipulate tmp_df
    tmp_df = tmp_df*2

    data_list.append(tmp_df)

df = pd.concat(data_list, ignore_index=True)
df.reset_index(inplace=True)