Added script to re-hash model components for ensembling (#463)

* Added script to re-hash model components for ensembling

* Fixed the comment

script/code/rehash_model.py

@@ -0,0 +1,74 @@
+#!/usr/bin/env python3
+
+"""Usage: rehash_model.py MOD_IN MOD_OUT
+
+Takes a trained model and re-creates the unique hash of all of its components.
+This is useful when, for example, you want to ensemble models that have
+identical component names, such as two models that were adapted from the
+same original model.
+
+This script will:
+- Analyze MOD_IN to find all saved model components
+- Rehash all model components
+- Write out the rehashed model to MOD_OUT
+
+Options:
+  -h, --help               Display this helpful text.
+"""
+
+from docopt import docopt
+from glob import glob
+import os
+import shutil
+import random
+
+SUBCOL_TAG = "xnmt_subcol_name: "
+SEP = "C"
+
+subcol_rand = random.Random()
+
+def generate_hash():
+  rand_bits = subcol_rand.getrandbits(32)
+  rand_hex = "%008x" % rand_bits
+  return rand_hex
+
+def extract_components(mod_infile):
+  components = set([])
+  yaml_lines = []
+  with open(mod_infile, 'r', encoding="utf-8") as file_:
+    for line in file_:
+      yaml_lines.append(line)
+      if SUBCOL_TAG in line:
+        type_name, hash_name = line.strip().split(SUBCOL_TAG)[-1].split('.')
+        components.add((type_name, hash_name))
+  return components, yaml_lines
+
+def rewrite_components(mod_infile, mod_outfile, components, yaml_lines):
+  new_hashes = {} 
+  os.mkdir(f"{mod_outfile}.data")
+  for type_name, hash_name in components:
+    new_hash = generate_hash()
+    new_hashes[hash_name] = new_hash
+    shutil.copy(f"{mod_infile}.data/{type_name}.{hash_name}",
+                f"{mod_outfile}.data/{type_name}.{new_hash}")
+  with open(f"{mod_infile}", 'r', encoding="utf-8") as file_in, \
+       open(f"{mod_outfile}", 'w', encoding="utf-8") as file_out:
+    for line in yaml_lines:
+      if SUBCOL_TAG in line:
+        part = line.strip().split('.')
+        if part[-1] in new_hashes:
+          line = line.replace(part[-1], new_hashes[part[-1]])
+      file_out.write(line)
+
+def main(mod_infile, mod_outfile):
+  components, yaml_lines = extract_components(mod_infile)
+  print("Found {:3d} model components.".format(len(components)))
+
+  rewrite_components(mod_infile, mod_outfile, components, yaml_lines)
+
+  print("All done.")
+
+
+if __name__ == "__main__":
+  args = docopt(__doc__)
+  main(args['MOD_IN'], args['MOD_OUT'])