From ea02f36235420e1ec4afc621b728f3dfd87fc7f5 Mon Sep 17 00:00:00 2001
From: Andy Eschbacher <andy.eschbacher@gmail.com>
Date: Wed, 30 Mar 2016 15:37:51 -0400
Subject: [PATCH] adding condition to avoid self-comparison in neighbor queries

---
 .../crankshaft/pysal_utils/pysal_utils.py     | 13 +++++++----
 src/py/crankshaft/test/test_pysal_utils.py    | 23 +++++++++++--------
 2 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/src/py/crankshaft/crankshaft/pysal_utils/pysal_utils.py b/src/py/crankshaft/crankshaft/pysal_utils/pysal_utils.py
index 9fdbfb3..fa06e26 100644
--- a/src/py/crankshaft/crankshaft/pysal_utils/pysal_utils.py
+++ b/src/py/crankshaft/crankshaft/pysal_utils/pysal_utils.py
@@ -89,9 +89,11 @@ def knn(params):
                 "%(attr_select)s" \
                 "(SELECT ARRAY(SELECT j.\"{id_col}\" " \
                               "FROM ({subquery}) As j " \
-                              "WHERE %(attr_where_j)s AND " \
-                                    "i.\"{id_col}\" <> j.\"{id_col}\" " \
-                              "ORDER BY j.\"{geom_col}\" <-> i.\"{geom_col}\" ASC " \
+                              "WHERE " \
+                                "i.\"{id_col}\" <> j.\"{id_col}\" AND " \
+                                "%(attr_where_j)s " \
+                              "ORDER BY " \
+                                "j.\"{geom_col}\" <-> i.\"{geom_col}\" ASC " \
                               "LIMIT {num_ngbrs})" \
                 ") As neighbors " \
             "FROM ({subquery}) As i " \
@@ -118,8 +120,9 @@ def queen(params):
                 "%(attr_select)s" \
                 "(SELECT ARRAY(SELECT j.\"{id_col}\" " \
                  "FROM ({subquery}) As j " \
-                 "WHERE ST_Touches(i.\"{geom_col}\", j.\"{geom_col}\") AND " \
-                 "%(attr_where_j)s)" \
+                 "WHERE i.\"{id_col}\" <> j.\"{id_col}\" AND " \
+                       "ST_Touches(i.\"{geom_col}\", j.\"{geom_col}\") AND " \
+                       "%(attr_where_j)s)" \
                 ") As neighbors " \
             "FROM ({subquery}) As i " \
             "WHERE " \
diff --git a/src/py/crankshaft/test/test_pysal_utils.py b/src/py/crankshaft/test/test_pysal_utils.py
index 8e9b7da..4ea0d9b 100644
--- a/src/py/crankshaft/test/test_pysal_utils.py
+++ b/src/py/crankshaft/test/test_pysal_utils.py
@@ -40,12 +40,13 @@ class PysalUtilsTest(unittest.TestCase):
                      "i.\"jay_z\"::numeric As attr2, " \
                      "(SELECT ARRAY(SELECT j.\"cartodb_id\" " \
                                    "FROM (SELECT * FROM a_list) As j " \
-                                   "WHERE j.\"andy\" IS NOT NULL AND " \
-                                         "j.\"jay_z\" IS NOT NULL AND " \
-                                         "j.\"jay_z\" <> 0 AND " \
-                                         "i.\"cartodb_id\" <> j.\"cartodb_id\" " \
+                                   "WHERE " \
+                                    "i.\"cartodb_id\" <> j.\"cartodb_id\" AND " \
+                                    "j.\"andy\" IS NOT NULL AND " \
+                                    "j.\"jay_z\" IS NOT NULL AND " \
+                                    "j.\"jay_z\" <> 0 " \
                                    "ORDER BY " \
-                                     "j.\"the_geom\" <-> i.\"the_geom\" ASC " \
+                                    "j.\"the_geom\" <-> i.\"the_geom\" ASC " \
                       "LIMIT 321)) As neighbors " \
               "FROM (SELECT * FROM a_list) As i " \
               "WHERE i.\"andy\" IS NOT NULL AND " \
@@ -63,11 +64,13 @@ class PysalUtilsTest(unittest.TestCase):
                      "i.\"jay_z\"::numeric As attr2, " \
                      "(SELECT ARRAY(SELECT j.\"cartodb_id\" " \
                                    "FROM (SELECT * FROM a_list) As j " \
-                                   "WHERE ST_Touches(i.\"the_geom\", " \
-                                                    "j.\"the_geom\") AND " \
-                                         "j.\"andy\" IS NOT NULL AND " \
-                                         "j.\"jay_z\" IS NOT NULL AND " \
-                                         "j.\"jay_z\" <> 0)" \
+                                   "WHERE " \
+                                   "i.\"cartodb_id\" <> j.\"cartodb_id\" AND " \
+                                   "ST_Touches(i.\"the_geom\", " \
+                                              "j.\"the_geom\") AND " \
+                                   "j.\"andy\" IS NOT NULL AND " \
+                                   "j.\"jay_z\" IS NOT NULL AND " \
+                                   "j.\"jay_z\" <> 0)" \
                                   ") As neighbors " \
               "FROM (SELECT * FROM a_list) As i " \
               "WHERE i.\"andy\" IS NOT NULL AND " \