如果 python 中的某些条件，则 Append 字符串到上一行

Question

I have csv file with single column, in some cases the last value gets more space and create new row, here I need to find out and append it to the previous line

for eg:

my python code:

with open("01.csv", 'r+') as file:
    text = str()
    for line in file:
        if line[0:3] == "2021":
           text = "{} {}".format(text, line.strip())
        else:
             text = "{}\n{}".format(text, line.strip())
            
    file.seek(0)
    file.write(text[1:])

How to remove || this in last and append next line to it in all occurrence.

Line no 10 to be appended to line no 9 and line no 21 to be appended to line no 20 nd so on..

Answer 1

You can't "append next line" if you haven't seen it yet. Your solution has to know that all appends are complete before otherwise acting on a line, which means you need to buffer the next line.

I think you're trying to re-compose the whole file in text as you go, which isn't a great model for file handling. And if your test were working, the actions are actually the wrong way around - you want to include the newline when "20" starts the line. I suggest that instead you write to another new file or simply correct the issue on the fly as below.

with open("01.csv", 'r+') as file:
    complete_line = None
    for line in file:
        if complete_line is None:
           initial_action()
           complete_line = line
        elif line[0:2] == "20": # compatible with next 79 years
           act_on(complete_line)
           complete_line = line
        else:
           complete_line += line

    act_on(complete_line)        

where intial_action and act_on are functions for you to implement.