From e7bed15ee82f217e1246623f0b684a4f5559b866 Mon Sep 17 00:00:00 2001
From: "Brian S. Stephan" <bss@incorporeal.org>
Date: Fri, 8 Feb 2013 02:07:57 -0600
Subject: [PATCH] Markov: _retrieve_random_v_for_k1_and_k2_with_pref

get one random v for a k1,k2 via SQL. prefer a word to show up in the
results, though there's no guarantee it will. this simplifies the
general looking forward case, and could possibly even work ok on the new
sentence stuff, though i haven't tried to update that portion of the
code yet
---
 modules/Markov.py | 60 +++++++++++++++++++++++++++++++++++++----------
 1 file changed, 47 insertions(+), 13 deletions(-)

diff --git a/modules/Markov.py b/modules/Markov.py
index 6bb29ef..b2f9125 100644
--- a/modules/Markov.py
+++ b/modules/Markov.py
@@ -413,20 +413,21 @@ class Markov(Module):
                 hit_word = seed_word
             else:
                 # work forwards
-
-                key_hits = self._retrieve_chains_for_key(gen_words[-2], gen_words[-1], context_id)
-
-                # use the chain that includes the target word, if it is found
-                if seed_word is not None and seed_word in key_hits:
-                    hit_word = seed_word
-                    self.log.debug("added seed word '{0:s}' to gen_words".format(hit_word))
+                self.log.debug("looking forwards")
+                prefer = seed_word if seed_word else ''
+                self.log.debug("preferring: '{0:s}'".format(prefer))
+                forw_v = self._retrieve_random_v_for_k1_and_k2_with_pref(gen_words[-2],
+                                                                         gen_words[-1],
+                                                                         prefer, context_id)
+                if forw_v:
+                    gen_words.append(forw_v)
+                    self.log.debug("added random word '{0:s}' to gen_words".format(forw_v))
+                    self.log.debug("gen_words: {0:s}".format(" ".join(gen_words)))
                 else:
-                    hit_word = self._get_suitable_word_from_choices(key_hits, gen_words, min_size)
-                    self.log.debug("added random word '{0:s}' to gen_words".format(hit_word))
-
-                # from either method, append result
-                gen_words.append(hit_word)
-                self.log.debug("gen_words: {0:s}".format(" ".join(gen_words)))
+                    # append stop, let below code clean it up if necessary
+                    gen_words.append(self.stop)
+                    self.log.debug("nothing found, adding stop")
+                    self.log.debug("gen_words: {0:s}".format(" ".join(gen_words)))
 
                 # tack a new chain onto the list and resume if we're too short
                 if gen_words[-1] == self.stop and len(gen_words) < min_size + 3:
@@ -536,6 +537,39 @@ class Markov(Module):
             raise
         finally: cur.close()
 
+    def _retrieve_random_v_for_k1_and_k2_with_pref(self, k1, k2, prefer, context_id):
+        """Get one v for a given k1,k2.
+
+        Prefer that the result be prefer, if it's found.
+
+        """
+
+        values = []
+        db = self.get_db()
+        try:
+            query = '''
+                SELECT v FROM markov_chain AS r1
+                  JOIN (
+                    SELECT (RAND() * (SELECT MAX(id) FROM markov_chain)) AS id
+                  ) AS r2
+                  WHERE r1.id >= r2.id
+                    AND r1.k1 = %s
+                    AND r1.k2 = %s
+                    AND r1.context_id = %s
+                  ORDER BY r1.v = %s DESC, r1.id ASC
+                  LIMIT 1
+            '''
+            cur = db.cursor(mdb.cursors.DictCursor)
+            cur.execute(query, (k1, k2, context_id, prefer))
+            result = cur.fetchone()
+            if result:
+                return result['v']
+        except mdb.Error as e:
+            self.log.error("database error in _retrieve_random_v_for_k1_and_k2_with_pref")
+            self.log.exception(e)
+            raise
+        finally: cur.close()
+
     def _retrieve_random_k2_for_value(self, v, context_id):
         """Get one k2 for a given value."""