将多行写入 CSV

Question

I have a small GUI which should write the values into a CSV file. However, the header is always written instead of just the new entries.

this is how it looks in the csv:

Amount, Time
1000,12:13:40
Amount, Time
2000,12:14:30

What I want:

Amount, Time
1000,12:13:40
2000,12:14:30

def submit():
     import csv
     import datetime
     with open("Data_amount.csv", "a", newline="") as csvfile:
         writer = csv.writer(csvfile)
         #Header 
         writer.writerow(["Amount", "Time"])
         #Input
         input_amount = entry_listbox.get()
         #Time
         now = datetime.datetime.now()
         now_str = now.time().strftime("%H:%M:%S")
         writer.writerow([input_amount, now_str])

     timestamp = datetime.datetime.now()
     input_amount2 = entry_listbox.get() 

     if input_amount2 != "":
         listbox_stuekzahlen.insert(tkinter.END, f'{timestamp:%H:%M:%S} - {input_amount2} Stk.')
         entry_listbox.delete(0,tkinter.END)
     else:
        tkinter.messagebox.showwarning(title="Warning!", message="INPUT!")

Answer 1

You unconditionally write the header again each time you call submit . Either:

1. Remove that header write, and have, somewhere outside submit (early in your program, run exactly once), the code that initializes (opens in "w" mode so the file is cleared) the file with just the header, so each submit doesn't add an extra copy, or

2. Leave the header write it, but make it conditional on the file being empty (so you only write it when the file is already empty, and otherwise assume the file already has the header), eg

    with open("Data_amount.csv", "a", newline="") as csvfile: writer = csv.writer(csvfile) #Header if not os.fstat(csvfile.fileno()).st_size: writer.writerow(["Amount", "Time"]) # Write header only if input is empty