From d312e270ed5c2926c8651291a4026062213876f8 Mon Sep 17 00:00:00 2001
From: Jonathan Herman <hermanjl@cs.unc.edu>
Date: Fri, 8 Feb 2013 11:54:49 -0500
Subject: ColMaps are now created by ColMapBuilders which order columns by
 their number of distinct values.

---
 parse/col_map.py | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 parse/col_map.py

(limited to 'parse/col_map.py')

diff --git a/parse/col_map.py b/parse/col_map.py
new file mode 100644
index 0000000..6f83ca1
--- /dev/null
+++ b/parse/col_map.py
@@ -0,0 +1,79 @@
+from collections import defaultdict
+
+class ColMapBuilder(object):
+    def __init__(self):
+        self.value_map = defaultdict(set)
+
+    def build(self):
+        columns = sorted(self.value_map.keys(),
+                         key=lambda c: (len(self.value_map[c]), c))
+        col_list = filter(lambda c : len(self.value_map[c]) > 1, columns)
+        return ColMap(col_list)
+
+    def try_add(self, column, value):
+        self.value_map[column].add( value )
+
+    def try_remove(self, column):
+        del(self.value_map[column])
+
+class ColMap(object):
+    def __init__(self, col_list):
+        self.col_list = col_list
+        self.rev_map = {}
+
+        for i, col in enumerate(col_list):
+            self.rev_map[col] = i
+
+    def columns(self):
+        return self.col_list
+
+    def get_key(self, kv):
+        '''Convert a key-value dict into an ordered tuple of values.'''
+        key = ()
+
+        for col in self.col_list:
+            if col not in kv:
+                key += (None,)
+            else:
+                key += (kv[col],)
+
+        return key
+
+    def get_kv(self, key):
+        '''Convert an ordered tuple of values into a key-value dict.'''
+        kv = {}
+        for i in range(0, len(key)):
+            kv[self.col_list[i]] = key[i]
+        return kv
+
+
+    def encode(self, kv):
+        '''Converted a dict into a string with items sorted according to
+        the ColMap key order.'''
+        def escape(val):
+            return str(val).replace("_", "-").replace("=", "-")
+
+        vals = []
+
+        for key in self.col_list:
+            if key not in kv:
+                continue
+            k, v = escape(key), escape(kv[key])
+            vals += ["%s=%s" % (k, v)]
+
+        return "_".join(vals)
+
+    @staticmethod
+    def decode(string):
+        '''Convert a string into a key-value dict.'''
+        vals = {}
+        for assignment in string.split("_"):
+            k, v = assignment.split("=")
+            vals[k] = v
+        return vals
+
+    def __contains__(self, col):
+        return col in self.rev_map
+
+    def __str__(self):
+        return "<ColMap>%s" % (self.rev_map)
-- 
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