89a6d1a02972c7da55afb55e81a871870a03f260
max
  Thu Aug 5 03:54:34 2021 -0700
improving docs for chromToUcsc, refs #27919

diff --git src/utils/chromToUcsc/chromToUcsc src/utils/chromToUcsc/chromToUcsc
index c666c20..f9e8066 100755
--- src/utils/chromToUcsc/chromToUcsc
+++ src/utils/chromToUcsc/chromToUcsc
@@ -1,227 +1,232 @@
 #!/usr/bin/env python
 import logging, optparse, gzip
 from sys import stdin, stdout, stderr, exit, modules
 from os.path import basename
 
 try:
     from urllib.request import urlopen # py2
 except ImportError:
     from urllib2 import urlopen # py3
 try:
     from cStringIO import StringIO # py2
 except ImportError:
     from io import BytesIO # py3
 
 # ==== functions =====
 def parseArgs():
     " setup logging, parse command line arguments and options. -h shows auto-generated help page "
     parser = optparse.OptionParser("""usage: %prog [options] filename - change NCBI or Ensembl chromosome names to UCSC names in tabular or wiggle files, using a chromAlias table.
 
     Supports these UCSC file formats:
     BED, genePred, PSL, wiggle (all formats), bedGraph, VCF, SAM, GTF, Chain
     ... or any other csv or tsv format where the sequence (chromosome) name is a separate field.
 
     Requires a <genome>.chromAlias.tsv file which can be downloaded like this:
         %prog --get hg19              # download the file hg19.chromAlias.tsv into current directory
 
     If you do not want to use the --get option to retrieve the mapping tables, you can also download the alias mapping
     files yourself, e.g. for mm10 with 'wget https://hgdownload.soe.ucsc.edu/goldenPath/mm10/database/chromAlias.txt.gz'
 
     Then the script can be run like this:
         %prog -i in.bed -o out.bed -a hg19.chromAlias.tsv
         %prog -i in.bed -o out.bed -a https://hgdownload.soe.ucsc.edu/goldenPath/hg19/database/chromAlias.txt.gz
     Or in pipes, like this:
         cat test.bed | %prog -a mm10.chromAlias.tsv > test.ucsc.bed
-    For BAM files use in a pipe with samtools:
+    For BAM files use this program in a pipe with samtools:
         samtools view -h in.bam | ./chromToUcsc -a mm10.chromAlias.tsv | samtools -bS > out.bam
 
+    By default, this script expects the chromosome name in the first field, but you can change the field with -k.
+    This works for BED, bedGraph, GTF, wiggle, VCF.
+    For the following file formats, you will need to set the -k option to these values manually:
+    genePred: 2 -- PSL 10 (target) or 14 (query) -- chain: 2 (target) or 7 (query) -- SAM: 2
+    If any line starts with @ (SAM format), -k is automatically set to 2.
     """)
 
     parser.add_option("", "--get", dest="downloadDb", action="store", help="download a chrom alias table from UCSC for the genomeDb into the current directory and exit")
     parser.add_option("-a", "--chromAlias", dest="aliasFname", action="store", help="a UCSC chromAlias file in tab-sep format or the http/https URL to one")
     parser.add_option("-i", "--in", dest="inFname", action="store", help="input filename, default: /dev/stdin")
     parser.add_option("-o", "--out", dest="outFname", action="store", help="output filename, default: /dev/stdout")
     parser.add_option("-d", "--debug", dest="debug", action="store_true", help="show debug messages")
     parser.add_option("-s", "--skipUnknown", dest="skipUnknown", action="store_true", help="skip unknown sequence rather than generate an error.")
     parser.add_option("-k", "--field", dest="fieldNo", action="store", type="int", \
-            help="index of field to convert, default is %default (first field is 1). This works for BED, bedGraph, GTF, wiggle, VCF. For genePred, set this option to 2, for PSL use 10 (target) or 14 (query), for Chain use 2 (target) or 7 (query). If any line starts with @ (SAM format), this field is automatically set to 2.", default=1)
+            help="index of field to convert, default is %default (first field is 1). ", default=1)
 
     (options, args) = parser.parse_args()
 
     if options.downloadDb is None and options.aliasFname is None:
         parser.print_help()
         exit(1)
 
     if options.debug:
         logging.basicConfig(level=logging.DEBUG)
     else:
         logging.basicConfig(level=logging.INFO)
     return args, options
 
 # ----------- main --------------
 def splitLines(ifh):
     " yield (chromName, restOfLine) for all lines of ifh "
     sep = -1
     lineNo = 0
     for line in ifh:
         lineNo += 1
         if line.startswith("#"):
             yield lineNo, None, None, line.rstrip("\n\r")
         else:
             if line.startswith("fixedStep") or line.startswith("variableStep"):
                 row = line.split()
                 yield lineNo, " ", row, line # *step lines are always space-separated
             else:
                 if sep==-1:
                     # why test first for space? Because after fixedStep, the lines are just single numbers
                     if "\t" in line:
                         sep = "\t"
                     elif " " in line:
                         sep = None # = split on any whitespace, consec. whitespc counts as one
                     else:
                         sep = "\t" # default is to split on tab
                 row = line.rstrip("\n\r").split(sep)
                 if sep is None:
                     sep = " "
                 yield lineNo, sep, row, line
 
 def parseAlias(fname):
     " parse tsv file with at least two columns, orig chrom name and new chrom name "
     toUcsc = {}
     if fname.startswith("http://") or fname.startswith("https://"):
         ifh = urlopen(fname)
         if fname.endswith(".gz"):
             data = gzip.GzipFile(fileobj=ifh).read().decode()
             ifh = data.splitlines()
     elif fname.endswith(".gz"):
         ifh = gzip.open(fname, "rt")
     else:
         ifh = open(fname)
 
     for line in ifh:
         if line.startswith("alias"):
             continue
         row = line.rstrip("\n").split("\t")
         toUcsc[row[0]] = row[1]
     return toUcsc
 
 
 def handledUnmappedChrom(chrom, skipUnknown, skipWarned, message):
     "either generate an error or warning when an unknown chromosome is encountered."
     if skipUnknown:
         if chrom not in skipWarned:
             logging.warning(message)
             skipWarned.add(chrom)
     else:
         logging.error(message)
         exit(1)
 
 def chromToUcsc(aliasFname, fieldIdx, skipUnknown, ifh, ofh):
     " convert column number fieldIdx to UCSC-style chrom names "
     toUcsc = parseAlias(aliasFname)
     skipWarned = set()
 
     ucscChroms = set(toUcsc.values())
     isSam = False
 
     for lineNo, sep, row, line in splitLines(ifh):
         if line.startswith("#"):
             ofh.write(line) # comments (e.g. gtf) are just passed through
             ofh.write("\n")
             continue
         elif len(row)<=2:
             pass   # fixedStep or variableStep value lines are passed through
         elif row[0]=="fixedStep" or row[0]=="variableStep":
             # fixedStep chrom=NC_033660.1 start=15778865 step=1
             key, chrom = row[1].split("=")
             assert(key=="chrom") # we assume that the first field has the chrom, that saves a lot of time
             ucscChrom = toUcsc.get(chrom)
             if ucscChrom is None:
                 logging.error("line %d: chrom name %s is not in chromAlias table" % (lineNo, repr(chrom)))
                 exit(1)
             row[1] = "chrom="+ucscChrom
 
         elif row[0][0]== "@":
             fieldIdx = 2 # SAM format detected
             isSam = True
             if row[0]=="@SQ":
                 # @SQ     SN:1    LN:195471971
                 chrom = row[1].split(":")[1]
                 if chrom not in ucscChroms:
                     ucscChrom = toUcsc.get(chrom)
                     if ucscChrom is None:
                         handledUnmappedChrom(chrom, skipUnknown, skipWarned,
                                              "SAM format, header line %d: chrom name %s is not in chromAlias table" % (lineNo, repr(chrom)))
                         continue
                     row[1] = "SN:%s" % ucscChrom
         else:
             # just pass through any UCSC chrom names
             chrom = row[fieldIdx]
             if row[0].startswith("#") or chrom in ucscChroms or chrom=="*":
                 ucscChrom = chrom
             else:
                 ucscChrom = toUcsc.get(chrom)
                 if ucscChrom is None:
                     handledUnmappedChrom(chrom, skipUnknown, skipWarned,
                                          "line %d: chrom name %s is not in chromAlias table" % (lineNo, repr(chrom)))
                     continue
             if isSam:
                 mateChrom = row[6]
                 if mateChrom not in ("=", "*"):
                     row[6] = toUcsc[mateChrom]
 
             row[fieldIdx] = ucscChrom
 
         line = sep.join(row)
         ofh.write(line)
         ofh.write("\n")
 
 def download(db):
     url = "http://hgdownload.soe.ucsc.edu/goldenPath/%s/database/chromAlias.txt.gz" % db
     gzData = urlopen(url).read()
 
     if 'cStringIO' in modules:
         data = StringIO(gzData)
     else:
         data = BytesIO(gzData)
 
     data = gzip.GzipFile(fileobj=data).read().decode()
     outFname = db+".chromAlias.tsv"
     open(outFname, "w").write(data)
     print("Wrote %s to %s" % (url, outFname))
     print("You can now convert a file with 'chromToUcsc -a %s -i infile.bed -o outfile.bed'" % outFname)
     exit(0)
 
 def main():
     args, options = parseArgs()
 
     aliasFname = options.aliasFname
     inFname = options.inFname
     outFname = options.outFname
     skipUnknown = options.skipUnknown
 
     if options.downloadDb:
         download(options.downloadDb)
 
     if aliasFname is None:
         logging.error("You need to provide an alias table with the -a option or use --get to download one.")
         exit(1)
 
     if inFname is None:
         ifh = stdin
     elif inFname.endswith(".gz"):
         ifh = gzip.open(inFname, "rt")
     else:
         ifh = open(inFname)
 
     if outFname is None:
         ofh = stdout
     elif outFname.endswith(".gz"):
         ofh = gzip.open(outFname, "wt")
     else:
         ofh = open(outFname, "w")
 
     fieldIdx = options.fieldNo-1
     chromToUcsc(aliasFname, fieldIdx, skipUnknown, ifh, ofh)
 
 main()