tsv head/tail

tsv/tsvhead

@@ -0,0 +1,90 @@
+#!/usr/bin/env python
+#
+# Copyright 2015 Ville Rantanen
+#
+# This program is free software: you can redistribute it and/or modify it
+# under the terms of the GNU Lesser General Public License as published
+# by the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+'''simple head for tsv/csv files.'''
+
+__author__ = "Ville Rantanen <ville.q.rantanen@gmail.com>"
+
+__version__ = "0.1"
+
+import sys,os,argparse
+from argparse import ArgumentParser 
+
+def setup_options():
+    ''' Create command line options '''
+    usage='''
+Simple implementation of head that keeps the header row.
+
+'''
+ 
+    parser=ArgumentParser(description=usage,
+                          formatter_class=argparse.RawDescriptionHelpFormatter,
+                          epilog="\n".join(["Version: "+__version__,__author__]))
+    common_group=parser.add_argument_group('common', 'Common options')
+    common_group.add_argument("-v","--version",action="version",version=__version__)
+    common_group.add_argument("-n",type=int,dest="lines",default=False,
+                     help="Lines to show from beginning of file. Negative value to show lines but the number. Default: 10")
+    parser.add_argument("file",type=str, nargs='*',
+                     help="File(s) to be headed")
+    opts=parser.parse_args()
+    if not opts.lines:
+        int(opts.file[0])
+        opts.lines=int(opts.file.pop(0))
+    if not opts.lines:
+        opts.lines=10
+    return opts
+
+def behead(fileob,opts):
+
+    header=fileob.readline()
+    sys.stdout.write(header)
+    if opts.lines>=0:
+        head_ordinary(fileob, opts.lines)
+    else:
+        head_allbutlast(fileob, opts.lines)
+    
+def head_ordinary(fileob, lines):
+    for i,row in enumerate(fileob):
+        if i>lines-1:
+            break
+        sys.stdout.write(row)
+
+def head_allbutlast(fileob, lines):
+    lines=-lines
+    buf=[]
+    for row in fileob:
+        buf.append(row)
+        if len(buf)>lines:
+            sys.stdout.write(buf.pop(0))
+
+def main():
+    opts=setup_options()
+    try:
+        if (not sys.stdin.isatty()):
+            behead(sys.stdin, opts)
+        for fi in opts.file:
+            behead(open(fi,'r'), opts)
+    except IOError as (n,e):
+        if  n==32:
+            pass
+        else:
+            import traceback
+            print traceback.format_exc()
+
+if __name__ == "__main__":
+    main()