diff --git a/README.markdown b/README.markdown
index d68202f..a632121 100644
--- a/README.markdown
+++ b/README.markdown
@@ -73,8 +73,8 @@ Generate an ascii bar chart for input data (this is like a visualization of `uni
     14:40 [    49] ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎
     14:41 [    14] ∎∎∎∎∎∎∎∎∎∎∎∎∎∎
 
-bar_chart.py also supports ingesting aggregated values. Simply provide a two column input of key<space>value:
+`bar_chart.py` and `histogram.py` also support ingesting pre-aggregated values. Simply provide a two column input of `count<whitespace>value` for `-a` or `value<whitespace>count` for `-A`:
 
-    $ cat data | uniq -c | bar_chart.py --sort-keys --agg-values
+    $ cat data | uniq -c | bar_chart.py -a
 
 This is very convenient if you pull data out, say Hadoop or MySQL already aggregated.
diff --git a/data_hacks/bar_chart.py b/data_hacks/bar_chart.py
index 3551860..13f76a8 100755
--- a/data_hacks/bar_chart.py
+++ b/data_hacks/bar_chart.py
@@ -41,11 +41,16 @@ def run(input_stream, options):
     data = defaultdict(int)
     total = 0
     for row in input_stream:
-        if options.agg_values:
-            kv = row.replace('\t', ' ').split(' ',2);
+        if options.agg_key_value:
+            kv = row.rstrip().rsplit(None, 1)
             value = int(kv[1])
             data[kv[0]] += value
             total += value
+        elif options.agg_value_key:
+            kv = row.lstrip().split(None, 1)
+            value = int(kv[0])
+            data[kv[1]] += value
+            total += value
         else:
             data[row] += 1
             total += 1
@@ -85,7 +90,9 @@ def run(input_stream, options):
 if __name__ == "__main__":
     parser = OptionParser()
     parser.usage = "cat data | %prog [options]"
-    parser.add_option("-a", "--agg-values", dest="agg_values", default=False, action="store_true",
+    parser.add_option("-a", "--agg", dest="agg_value_key", default=False, action="store_true",
+                        help="Two column input format, space seperated with value<space>key")
+    parser.add_option("-A", "--agg-key-value", dest="agg_key_value", default=False, action="store_true",
                         help="Two column input format, space seperated with key<space>value")
     parser.add_option("-k", "--sort-keys", dest="sort_keys", default=True, action="store_true",
                         help="sort by the key [default]")
diff --git a/data_hacks/histogram.py b/data_hacks/histogram.py
index 72b3806..042a02f 100755
--- a/data_hacks/histogram.py
+++ b/data_hacks/histogram.py
@@ -76,7 +76,7 @@ def test_mvsd():
     assert '%.2f' % mvsd.var() == "8.25"
     assert '%.14f' % mvsd.sd() == "2.87228132326901"
 
-def load_stream(input_stream, agg):
+def load_stream(input_stream, agg_value_key, agg_key_value):
     for line in input_stream:
         clean_line = line.strip()
         if not clean_line:
@@ -85,11 +85,14 @@ def load_stream(input_stream, agg):
         if clean_line[0] in ['"', "'"]:
             clean_line = clean_line.strip("\"'")
         try:
-            if agg:
-                value, count = line.replace("\t", ' ').split(' ', 2)
-                yield DataPoint(Decimal(value), int(count))
-                continue
-            yield DataPoint(Decimal(clean_line), 1)
+            if agg_key_value:
+                key, value = clean_line.rstrip().rsplit(None, 1)
+                yield DataPoint(Decimal(key), int(value))
+            elif agg_value_key:
+                value, key = clean_line.lstrip().split(None, 1)
+                yield DataPoint(Decimal(key), int(value))
+            else:
+                yield DataPoint(Decimal(clean_line), 1)
         except:
             logging.exception('failed %r', line)
             print >>sys.stderr, "invalid line %r" % line
@@ -219,7 +222,9 @@ def histogram(stream, options):
 if __name__ == "__main__":
     parser = OptionParser()
     parser.usage = "cat data | %prog [options]"
-    parser.add_option("-a", "--agg", dest="agg", default=False, action="store_true",
+    parser.add_option("-a", "--agg", dest="agg_value_key", default=False, action="store_true",
+                        help="Two column input format, space seperated with value<space>key")
+    parser.add_option("-A", "--agg-key-value", dest="agg_key_value", default=False, action="store_true",
                         help="Two column input format, space seperated with key<space>value")
     parser.add_option("-m", "--min", dest="min",
                         help="minimum value for graph")
@@ -242,5 +247,5 @@ def histogram(stream, options):
         parser.print_usage()
         print "for more help use --help"
         sys.exit(1)
-    histogram(load_stream(sys.stdin, options.agg), options)
+    histogram(load_stream(sys.stdin, options.agg_value_key, options.agg_key_value), options)