If the csv file is more than 3 lines, edit it to delete the first line (Not save as new file)-CodePudding

Im trying to code if the csv file is more than 3 lines, edit it to delete the first line.

I want to delete the first line from the existing file instead of saving it as a new file.

For this reason, I had to delete the existing file and create a file with the same name but only one line is saved and the comma disappears.

I'm using Pandas data frame. But if it doesn't matter if I don't use it, I don't want to use it

Function name might be weird because I'm a beginner

Thanks.

file = open("./csv/selllist.csv", encoding="ANSI")
reader = csv.reader(file)
lines= len(list(reader))


if lines > 3:
    df = pd.read_csv('./csv/selllist.csv', 'r ', encoding="ANSI")
    dfa = df.iloc[1:]
    
    print(dfa)

    with open("./csv/selllist.csv", 'r ', encoding="ANSI") as x:
        x.truncate(0)
    with open('./csv/selllist.csv', 'a', encoding="ANSI", newline='') as fo:  
        # Pass the CSV  file object to the writer() function
        wo = writer(fo)
        # Result - a writer object
        # Pass the data in the list as an argument into the writerow() function
        wo.writerow(dfa)  
        # Close the file object
        fo.close()
print()

This is the type of csv file I deal with

string, string, string, string, string
string, string, string, string, string 
string, string, string, string, string
string, string, string, string, string

CodePudding user response：

With pandas, you can just specify header=None while reading and writing:

if lines > 3:
    df = pd.read_csv("data.csv", header=None)
    df.iloc[1:].to_csv("data.csv", header=None, index=None)

CodePudding user response：

Take a 2-step approach.

Open the file for reading and count the number of lines. If there are more than 3 lines, re-open the file (for writing) and update it.

For example:

lines = []
with open('./csv/selllist.csv') as csv:
  lines = csv.readlines()
if len(lines) > 3:
  with open('./csv/selllist.csv', 'w') as csv:
    for line in lines[1:]: # skip first line
      csv.write(line)