How to link two python scripts

[Larz60+]

Here is the final program. It Sorts and Selects in one module.

It is written so that you can run it from the command line using:

python SelsectAndSortFasta infilename outfilename min_seq_size

Or, you can import it into another program and call from within similar to:

# Add following import at top of your program
import SelectAndSortFasta

# In your initialization routine, add:
# If a class:
    self.sasf = SelectAndSortFasta.SelectAndSortFasta()
# If just a function:
    sasf = SelectAndSortFasta.SelectAndSortFasta()

# Then when you want to run a file
    sasf.sort_fasta_file(infile, outfile, minlen)

Here's the code:

from operator import itemgetter
import sys


class SelectAndSortFasta:
    """
    Sort in decreasing size order
    """
    def __init__(self):
        self.headers = []
        self.infile = None
        self.outfile = None
        self.minlen = 0

    def ExtractHeader(self):
        """
        Reads all headers, saves starting file position, header, and size in self.headers
        :return: None
        """
        seqlen = 0
        this_header = []
        firstseq = True

        f = open(self.infile, 'r')
        f.seek(0, 2)
        file_size = f.tell()
        f.seek(0)
        while True:
            fptr = f.tell()
            if fptr == file_size:
                break
            line = None
            line = f.readline()
            line = line.strip()

            # skip empty lines
            if len(line) > 0:
                # print(f'line len: {len(line)}')
                if line.startswith('>'):
                    if firstseq:
                        firstseq = False
                    else:
                        this_header.append(seqlen)
                        self.headers.append(this_header)

                    seqlen = 0
                    this_header = []
                    this_header.append(fptr)
                    this_header.append(line)
                else:
                    seqlen += len(line)
        this_header.append(seqlen)
        self.headers.append(this_header)
        f.close()
        # This is the sort routine, sorts on column 2 (size) of self.headers, in reverse order
        self.headers.sort(key=itemgetter(2), reverse=True)
        self.show_header()

    def show_header(self):
        """
        display self.headers list
        :return: None
        """
        for item in self.headers:
            print(f'File ptr: {item[0]}, Size: {item[2]}, Header: {item[1]}')

    def write_outfile(self):
        """
        Reads self.headers (which is sorted in reverse size order,
        seeks to that record in the inout file (from file pointer which i in column 0 of self.headers)
        and writes the output file
        :return:
        """
        with open(self.infile) as f, open(self.outfile, 'w') as fo:
            for item in self.headers:
                # Ignore entry if too small
                if item[2] < minlen:
                    continue
                f.seek(item[0], 0)
                fo.write(f.readline())
                while True:
                    buf = f.readline()
                    if buf.startswith('>'):
                        break
                    fo.write(buf)

    def sort_fasta_file(self, infile, outfile, minlen):
        """
        Launch pad for sort and select program
        :param infile: Name of input fasta file
        :param outfile: Name of output fasta file
        :param minlen: Minimun size of output record. (smaller inut records are ignored)
        :return: None
        """
        self.infile = infile
        self.outfile = outfile
        self.minlen = minlen
        self.ExtractHeader()
        self.write_outfile()


if __name__ == '__main__':
    # Test routine
    srtf = SelectAndSortFasta()
    numargs = len(sys.argv)
    if numargs > 1:
        infile = sys.argv[1]
        outfile = sys.argv[2]
        minlen = sys.argv[3]
    else:
        infile = 'data/fasta/AINZ01/AINZ01.1.fsa_nt'
        outfile = 'data/fasta/AINZ01/AINZ01sorted.1.fsa_nt'
        minlen = 1000

    srtf.sort_fasta_file(infile, outfile, minlen)

You may want to supress the printout on line 57 (self.show_header())