Deleting rows in a text file

A sample of the following text file i have is:

> 1 -4.6    -4.6    -7.6
> 
> 2 -1.7    -3.8    -3.1
> 
> 3 -1.6    -1.6    -3.1

the data is separated by tabs in the text file and the first column indicates the position.

I need to iterate through every value in the text file apart from column 0 and find the lowest value.

once the lowest value has been found that value needs to be written to a new text file along with the column name and position. Column 0 has the name "position" Column 1 "fifteen", column 2 "sixteen" and column 3 "seventeen"

for example the lowest value in the above data is "-7.6" and is in column 3 which has the name "seventeen". Therefore "7.6", "seventeen" and its position value which in this case is 1 need to be written to the new text file.

I then need a number of rows deleted from the above text file.

E.G. the lowest value above is "-7.6" and is found at position "1" and is found in column 3 which as the name "seventeen". I therefore need seventeen rows deleted from the text file starting from and including position 1

so the the column in which the lowest value is found denotes the amount of rows that 开发者_JS百科needs to be deleted and the position it is found at states the start point of the deletion

---

Open this file for reading, another file for writing, and copy all the lines that don't match the filter:

readfile = open('somefile', 'r')
writefile = open('otherfile', 'w')

for line in readfile:
  if not somepredicate(line):
    writefile.write(line)

readfile.close()
writefile.close()

---

Here's a stab at what I think you wanted (though your requirements were kind of difficult to follow):

def extract_bio_data(input_path, output_path):
    #open the output file and write it's headers
    output_file = open(output_path, 'w')
    output_file.write('\t'.join(('position', 'min_value', 'rows_skipped')) + '\n')

    #map column indexes (after popping the row number) to the number of rows to skip
    col_index = { 0: 15, 
                  1: 16, 
                  2: 17 }

    skip_to_position = 0
    for line in open(input_path, 'r'):
        #remove the '> ' from the beginning of the line and strip newline characters off the end
        line = line[2:].strip()

        #if the line contains no data, skip it
        if line == '':
            continue

        #split the columns on whitespace (change this to split('\t') for splitting only on tabs)
        columns = line.split()

        #extract the row number/position of this data
        position = int(columns.pop(0))

        #this is where we skip rows/positions
        if position < skip_to_position:  
            continue

        #if two columns share the minimum value, this will be the first encountered in the list
        min_index = columns.index(min(columns, key=float))

        #this is an integer version of the 'column name' which corresponds to the number of rows that need to be skipped
        rows_to_skip = col_index[min_index]

        #write data to your new file (row number, minimum value, number of rows skipped)
        output_file.write('\t'.join(str(x) for x in (position, columns[min_index], rows_to_skip)) + '\n')

        #set the number of data rows to skip from this position
        skip_to_position = position + rows_to_skip


if __name__ == '__main__':
    in_path = r'c:\temp\test_input.txt'
    out_path = r'c:\temp\test_output.txt'
    extract_bio_data(in_path, out_path)

Things that weren't clear to me:

1. Is there really "> " at the beginning of each line or is that a copy/paste error?
   • I assumed it wasn't an error.
2. Did you want "7.6" or "-7.6" written to the new file?
   • I assumed you wanted the original value.
3. Did you want to skip rows in the file? or positions based on the first column?
   • I assumed you wanted to skip positions.
4. You say you want to delete data from the original file.
   • I assumed that skipping positions was sufficient.