Python change headerrow of textfile (.csv)

Question

I have a txt file where the headerrow is incorrect. How do I replace the headerrow with the correct one?

old_header = "1;2;3;4;5;"
new_header = "1;2;3;4;5;6;7;8"

If I read the file with I don't get the first line.

    with open(full_path) as file:
        first_line = file.readline()

CompanyNumber;AccountingYear;Schema;RAT001;RAT002;RAT003;RAT004;RAT005;RAT006;RAT007;RAT008;RAT009;RAT010;RAT011;RAT012;RAT013;RAT014;RAT015;RAT016;RAT017;RAT018;RAT019;RAT020;RAT021;RAT101;RAT102;RAT103;RAT104;RAT105;RAT106;RAT107;RAT108;RAT109;RAT110;RAT111;RAT112;RAT113;RAT114;RAT115;RAT116;RAT117;RAT118;RAT119;RAT120;RAT121;RAT125;RAT127;RAT201;RAT202;RAT203;RAT204;RAT205;RAT206;RAT207;RAT208;RAT209;RAT210;RAT211;RAT212;RAT213;RAT214;RAT217;RAT218;RAT219;RAT220;RAT221
9999999999;2020;Abbreviated with capital;;;;;;;;;;;;;;;;;;;;;;;;;;;;-10.7;0.33;-1.57;-3.8;-3.74;-1.5;;;;;;;100;;;;;;;;;;;;;;;;;;;;;;;
8888888888;2020;Full with capital;11.16;8.34;90.25;67804.74;80.92;87.52;3.97;0.16;15.22;20.41;12.65;9.48;1.67;2;;;4.82;91.32;61.21;8.94;17.06;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

Red: headerrow where there needs to be added ;x1;x2;x3

Does this answer your question? [Search and replace a line in a file in Python](https://stackoverflow.com/questions/39086/search-and-replace-a-line-in-a-file-in-python) — RandomGuy, Dec 22 '22 at 07:26
What do you mean by you don't get the first line? Did you try to print out `first_line` to see what it contains? Replacing contents of a file means either rewriting the file or using fileinput with the replace option. — Cow, Dec 22 '22 at 07:27
@RandomGuy: this replaces a line in the file not the first line. — Tralala, Dec 22 '22 at 07:39
@Tralala You need to provide an example of the contents of the file. — Cow, Dec 22 '22 at 07:41
Please post text as *text*, not an image. We're not going to manually type it in to try it. — Mark Tolonen, Dec 22 '22 at 07:54
just as an FYI, if you change the number of columns in the header, you also need to change the number of columns in each row — Edo Akse, Dec 22 '22 at 08:14
@EdoAkse: there is a problem with the columnheader, it only has 66 columns, and the data (some lines) had 99. I tried changing it manually (header) and I can load the data in pandas. — Tralala, Dec 22 '22 at 08:17
I think the solution is add headers to and for other rows add empty values for these three headers: `;x1;x2;x3` — Reza Akraminejad, Dec 22 '22 at 08:19

score 0 · Accepted Answer · answered Dec 22 '22 at 08:26

read the file, strip the end of line character, add the needed part to the first line, write new file (with new EOL characters)

with open("data.csv") as infile:
    data = infile.read().splitlines()

data[0] = data[0] + ";x1;x2;x3"

with open("outfile.csv", "w") as outfile:
    for line in data:
        outfile.write(line+"\n")

Python change headerrow of textfile (.csv)

1 Answers1