Create new column and assign value to new column

Question

i would like to seek help in assigning the filename value (eg. file1.txt) to a new col (eg. filename). However im stuck at the portion to create new column and assigning the value with the filename. No new column was seen when i export it as .csv. Appreciate if can advise whether my logic is wrong.

-raw text (no column names)-

file1.txt -> AL; 1A;
file1.txt -> BL; 2A;
file1.txt -> CL; 3A;

-sample file path - C:UsersCLDesktopfolderfile1.txt-

-desired output (add filename col)-

name class filename
AL   1A    file1.txt
BL   2A    file2.txt
CL   3A    file3.txt

-current progress-

import os
import pandas as pd
import glob

src_path = r'C:UsersCLDesktopfolder' #3 files total

for f in glob.glob(os.path.join(src_path ,"*.txt")):
    filename = f #file1.txt
    files = [pd.read_csv(f, delimiter=';', names = ['name', 'class'], index_col = False)]
    files_df = pd.DataFrame(files) #convert to df to add new column
    files_df['filename'] = f #assign value to new column

files_df = pd.concat(files_df) #concat all file data together
files_df.to_csv("df.csv")

---update---

#trying to include index value for each row's data.

#desired output
name class filename
AL   1A    file1_1.txt
AL   1A    file1_2.txt
BL   2A    file2_1.txt
BL   2A    file2_2.txt
CL   3A    file3_1.txt
CL   3A    file3_2.txt

import os
import pandas as pd
import glob

i = 0

src_path = r'C:UsersCLDesktopfolder' #3 files total

pd.concat([pd.read_csv(f, delimiter=';', names=['name', 'class'], index_col=False
                       ).assign(filename=f)
           for i, f in enumerate(glob.glob(os.path.join(src_path ,"*.txt"))), i+=1]
          ).to_csv("df.csv")

Asked By: panzers

||

Source

Answer 1

Untested, but I imagine your code should be changed to:

import os
import pandas as pd
import glob

src_path = r'C:UsersCLDesktopfolder' #3 files total


all_dfs = []

for f in glob.glob(os.path.join(src_path ,"*.txt")):
    tmp_df = pd.read_csv(f, delimiter=';', names=['name', 'class'], index_col=False)
    all_dfs.append(tmp_df.assign(filename=f))

files_df = pd.concat(all_dfs) #concat all file data together
files_df.to_csv("df.csv")

As a "one-liner":

import os
import pandas as pd
import glob

src_path = r'C:UsersCLDesktopfolder' #3 files total

pd.concat([pd.read_csv(f, delimiter=';', names=['name', 'class'], index_col=False
                       ).assign(filename=f)
           for f in glob.glob(os.path.join(src_path ,"*.txt"))]
          ).to_csv("df.csv")

Answered By: mozway

Create new column and assign value to new column

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