From 7db0258b5c49be554bface11249fa6c296f3348b Mon Sep 17 00:00:00 2001
From: Bjoern Brandenburg <bbb@bbb1-cs.cs.unc.edu>
Date: Thu, 4 Sep 2008 22:36:50 -0400
Subject: teach csv_tool to reorder columns

---
 csv_tool | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/csv_tool b/csv_tool
index 10f5ee0..674c51c 100755
--- a/csv_tool
+++ b/csv_tool
@@ -15,8 +15,9 @@ o = optparse.make_option
 
 opts = [
 
-#    o('-t', '--two', action='store', dest='double_val',  nargs=2, type='int',
-#      help='A two-parameter option.'),
+    o('-x', '--exchange', action='append', dest='col_xchg',
+      nargs=2, type='int',
+      help='Columns that should be switched with reorder.'),
 
     o('-c', '--column', action='store', dest='col', type='int',
       help='The column on which to operate.'),
@@ -30,6 +31,7 @@ opts = [
 
 defaults = {
     'col'          : 0,
+    'col_xcgh'     : [],
     }
 
 def make_vector_op(op):
@@ -84,6 +86,14 @@ def transpose(rows):
         for i in xrange(c):
             yield [at(j, i) for j in xrange(r) ]
 
+
+def reorder_columns(rows, xchg_pairs):
+    for r in rows:
+        print type(r)
+        for (x,y) in xchg_pairs:
+            r[x], r[y] = r[y], r[x]
+        yield r
+
 def select_by_key(rows, col, cast=None):
     by_key = defdict(list)
     order  = []
@@ -99,6 +109,9 @@ def select_by_key(rows, col, cast=None):
 class CsvApp(defapp.App):
     def __init__(self):
         defapp.App.__init__(self, opts, defaults)
+        self.options.col -= 1
+        self.options.col_xchg = [(x - 1, y - 1) for (x, y) in
+                                 self.options.col_xchg]
 
     def transform(self, make_iterator, ordered=True):
         """Average all rows with the same key in a given column."""
@@ -110,7 +123,8 @@ class CsvApp(defapp.App):
                 rows = csv.reader(open(fn, 'r'))
                 # set up transformation
                 if ordered:
-                    (order, by_key) = select_by_key(rows, self.options.col, float)
+                    (order, by_key) = select_by_key(rows, self.options.col,
+                                                    float)
                     rows = make_iterator(order, by_key)
                 else:
                     rows = make_iterator(rows)
@@ -137,5 +151,10 @@ class CsvApp(defapp.App):
     def do_transpose(self, _):
         self.transform(transpose, ordered=False)
 
+    def do_reorder(self, _):
+        self.transform(lambda rows: reorder_columns(rows,
+                                                    self.options.col_xchg),
+                       ordered=False)
+
 if __name__ == '__main__':
     CsvApp().launch()
-- 
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