1 files changed, 64 insertions, 0 deletions
diff --git a/bin/hash_candidates.py b/bin/hash_candidates.py
new file mode 100755
index 0000000..e59295e
--- /dev/null
+++ b/bin/hash_candidates.py
@@ -0,0 +1,64 @@
+#!/usr/bin/python
+#
+# Copyright 2014 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Given a list of candidates on stdin, produce a file of hashes ("map file").
+"""
+
+import csv
+import sys
+
+import rappor
+
+
+def HashCandidates(params, stdin, stdout):
+  num_bloombits = params.num_bloombits
+  csv_out = csv.writer(stdout)
+
+  for line in stdin:
+    word = line.strip()
+    row = [word]
+    for cohort in xrange(params.num_cohorts):
+      bloom_bits = rappor.get_bloom_bits(word, cohort, params.num_hashes,
+                                         num_bloombits)
+      for bit_to_set in bloom_bits:
+        # bits are indexed from 1.  Add a fixed offset for each cohort.
+        # NOTE: This detail could be omitted from the map file format, and done
+        # in R.
+        row.append(cohort * num_bloombits + (bit_to_set + 1))
+    csv_out.writerow(row)
+
+
+def main(argv):
+  try:
+    filename = argv[1]
+  except IndexError:
+    raise RuntimeError('Usage: hash_candidates.py <params file>')
+  with open(filename) as f:
+    try:
+      params = rappor.Params.from_csv(f)
+    except rappor.Error as e:
+      raise RuntimeError(e)
+
+  HashCandidates(params, sys.stdin, sys.stdout)
+
+
+if __name__ == '__main__':
+  try:
+    main(sys.argv)
+  except RuntimeError, e:
+    print >>sys.stderr, e.args[0]
+    sys.exit(1)