--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/numerics/cat_columns.py	Mon Feb 23 10:50:13 2015 -0800
@@ -0,0 +1,95 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+output columns of various CSV files
+
+Example::
+
+> cat-columns foo.csv:0 bar.csv:1,2,3 fleem.csv
+
+This will generate CSV output with the first column from `foo.csv`,
+the 2nd, 3rd, and 4th columns from `bar.csv`,
+and all columns from `fleem.csv`.
+"""
+
+# imports
+import argparse
+import csv
+import os
+import sys
+import time
+from collections import OrderedDict
+from .read import read_csv
+
+# module globals
+__all__ = ['cat_columns', 'CatColumnParser', 'main']
+
+def cat_columns(csv_files):
+    """
+    csv_files -- an iterable of 2-tuples of `path`, columns
+    """
+
+    rows = []
+
+class CatColumnParser(argparse.ArgumentParser):
+    """CLI option parser"""
+    def __init__(self, **kwargs):
+        kwargs.setdefault('formatter_class', argparse.RawTextHelpFormatter)
+        kwargs.setdefault('description', __doc__)
+        argparse.ArgumentParser.__init__(self, **kwargs)
+        self.add_argument('csv', nargs='+',
+                          help="path to CSV files and columns to output, delimited by ':' and comma-separated")
+        self.add_argument('-o', '--output', dest='output',
+                          type=argparse.FileType('a'), default=sys.stdout,
+                          help="where to output to, or stdout by default")
+        self.options = None
+
+    def parse_args(self, *args, **kw):
+        options = argparse.ArgumentParser.parse_args(self, *args, **kw)
+        self.validate(options)
+        self.options = options
+        return options
+
+    def validate(self, options):
+        """validate options"""
+
+def main(args=sys.argv[1:]):
+    """CLI"""
+
+    # parse command line options
+    parser = CatColumnParser()
+    options = parser.parse_args(args)
+
+    # get the data
+    csv_files = OrderedDict()
+    missing = []
+    for item in options.csv:
+        if ':' in item:
+            path, columns = item.rsplit(':', 1)
+            columns = columns.strip()
+            if columns:
+                columns = [int(column) for column in columns.split(',')]
+            else:
+                columns = None
+        else:
+            path = item
+            columns = None
+        if not os.path.exists(path):
+            missing.append(path)
+    if missing:
+        parser.error("File(s) not found:\n{}".format('\n'.join(missing)))
+
+    # concatenate the rows
+    data = cat_columns(csv_files.items())
+
+    # output it
+    writer = csv.writer(options.output)
+    for row in data:
+        writer.write_row(row)
+        options.output.flush()
+
+if __name__ == '__main__':
+    main()
+
+

--- a/setup.py	Thu Jan 22 13:41:19 2015 -0800
+++ b/setup.py	Mon Feb 23 10:50:13 2015 -0800
@@ -16,6 +16,7 @@
     from setuptools import setup
     kw['entry_points'] = """
     [console_scripts]
+    cat-columns = numerics.cat_columns:main
     interpolate = numerics.interpolation:main
     manipulate = numerics.manipulate:main
     plot = numerics.plot:main