Writing in a file without erase with f.write()

Question

I need to write a python script to iterate calculations on several instances, unfortunately the last test overwrites all those before.

Do you know a way to avoid this? Here is my code, thank you!

import subprocess
import os
from os import listdir
from os.path import isfile, join
import sys


files = [f for f in listdir("data/dataAlea2_50") if isfile(join("data/dataAlea2_50", f))]
K = [2,5]

commande = "g++ -std=c++11 *.cpp -o main -Wall"


subprocess.getoutput(commande)

for file in files:
    for k in K:


        tmp = subprocess.getoutput("./main" +" " + str(k) + " data/dataAlea2_50/"+ file)
        f = open("resulat.txt","w+")
        f.write("Voici les resultats pour k = " + str(k) + " et pour les données :" + file )
        f.write(tmp)


f.close()

Use `f = open("resulat.txt","a+")` – Irfanuddin Jan 29 '20 at 12:53 — Irfanuddin, Jan 29 '20 at 12:53

score 2 · Answer 1 · answered Jan 29 '20 at 12:52

2

Use open mode a:

f = open("resulat.txt", "a")

Unless you’re also reading from f, there is no need to specify + in the open mode.

Better yet, use a with statement to open the file.

answered Jan 29 '20 at 12:52

Konrad Rudolph

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wogsland · Accepted Answer · 2020-01-29T13:07:39.343

You want to append instead of write. For example:

import subprocess
import os
from os import listdir
from os.path import isfile, join
import sys


files = [f for f in listdir("data/dataAlea2_50") if isfile(join("data/dataAlea2_50", f))]
K = [2,5]

commande = "g++ -std=c++11 *.cpp -o main -Wall"


subprocess.getoutput(commande)

for file in files:
    for k in K:


        tmp = subprocess.getoutput("./main" +" " + str(k) + " data/dataAlea2_50/"+ file)
        with open("resulat.txt", "a") as f:
            f.write("Voici les resultats pour k = " + str(k) + " et pour les données :" + file )
            f.write(tmp)

where the important piece is using the "a" option instead of "w+" for the open function. You can find the full list of options here

A much better solution is to open the file for writing once, before the main loop. — tripleee, Jan 29 '20 at 13:04

Writing in a file without erase with f.write()

2 Answers2