Concatenate text file lines with condition in python-CodePudding

I have a text file in this format:

0.jpg 12,13,14,15,16
0.jpg 13,14,15,16,17
1.jpg 1,2,3,4,5
1.jpg 2,3,4,5,6

I want to check if the image name is the same and then concatenate those lines into one line with the following format:

0.jpg 12,13,14,15,16 13,14,15,16,17
1.jpg 1,2,3,4,5 2,3,4,5,6

I have tried something like this but don't know how to do the actual comparison and also don't quite know what logic to apply since the first line_elements[0] will be taken and compared with each other line's line_elements[0]

with open("file.txt", "r") as input:       # Read all data lines.
    data = input.readlines()
with open("out_file.txt", "w") as output:  # Create output file.
    for line in data:                      # Iterate over data lines.
        line_elements = line.split()       # Split line by spaces.
        line_updated = [line_elements[0]]  # Initialize fixed line (without undesired patterns) with image's name.
        if line_elements[0] = (next line's line_elements[0])???:
            for i in line_elements[1:]:    # Iterate over groups of numbers in current line.
               tmp = i.split(',')          # Split current group by commas.
               if len(tmp) == 5:
                  line_updated.append(','.join(tmp))

            if len(line_updated) > 1:      # If the fixed line is valid, write it to output file.
               output.write(f"{' '.join(line_updated)}\n")

Could be something like:

for i in range (len(data)):
if line_elements[0] in line[i] == line_elements[0] in line[i 1]:

   line_updated = [line_elements[0]]
   for i in line_elements[1:]:    # Iterate over groups of numbers in current line.
      tmp = i.split(',')          # Split current group by commas.
      if len(tmp) == 5:
         line_updated.append(','.join(tmp))

   if len(line_updated) > 1:      # If the fixed line is valid, write it to output file.
      output.write(f"{' '.join(line_updated)}\n")

CodePudding user response：

Save the first field of the line in a variable. Then check if the first field of the current line is equal to the value. If it is, append to the value, otherwise write the saved line and start a new output line.

current_name = None

with open("out_file.txt", "w") as output:
    for line in data:
        name, values = line.split()
        if name == current_name:
            current_values  = ' '   values
            continue
        if current_name:
            output.write(f'{current_name} {current_values}\n')
        current_name, current_values = name, values
    # write the last block
    if current_name:
        output.write(f'{current_name} {current_values}\n')