Remove python 2 compatibility import imap (#89)

## What is the goal of this PR?

Fix an issue where a python 2 only import (`imap`) was being used when the client is meant to be python 3 compatible.

## What are the changes implemented in this PR?

* Replace usages of `imap` with `six.moves.map`, which works across both versions.

Author: Adam Mitchell

grakn/service/Session/Concept/RemoteConcept.py

@@ -17,11 +17,10 @@
 # under the License.
 #
 
-from itertools import imap
-
 from grakn.service.Session.util import enums
 from grakn.service.Session.util.RequestBuilder import RequestBuilder
 from grakn.exception.GraknError import GraknError
+from six.moves import map
 
 
 class RemoteConcept(object):
@@ -163,7 +162,7 @@ def subs(self):
         """ Retrieve the sub schema concepts of this schema concept, as an iterator """
         subs_req = RequestBuilder.ConceptMethod.SchemaConcept.subs()
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.schemaConcept_subs_iter_res.schemaConcept),
                    self._tx_service.run_concept_iter_method(self.id, subs_req))
@@ -172,7 +171,7 @@ def sups(self):
         """ Retrieve the all supertypes (direct and higher level) of this schema concept as an iterator """
         sups_req = RequestBuilder.ConceptMethod.SchemaConcept.sups()
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.schemaConcept_sups_iter_res.schemaConcept),
                    self._tx_service.run_concept_iter_method(self.id, sups_req))
@@ -201,7 +200,7 @@ def attributes(self):
         """ Retrieve all attributes attached to this Type as an iterator """
         attributes_req = RequestBuilder.ConceptMethod.Type.attributes()
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.type_attributes_iter_res.attributeType),
                    self._tx_service.run_concept_iter_method(self.id, attributes_req))
@@ -210,7 +209,7 @@ def instances(self):
         """ Retrieve all instances of this Type as an iterator """
         instances_req = RequestBuilder.ConceptMethod.Type.instances()
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.type_instances_iter_res.thing),
                    self._tx_service.run_concept_iter_method(self.id, instances_req))
@@ -219,7 +218,7 @@ def playing(self):
         """ Retrieve iterator of roles played by this type """
         playing_req = RequestBuilder.ConceptMethod.Type.playing()
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.type_playing_iter_res.role),
                    self._tx_service.run_concept_iter_method(self.id, playing_req))
@@ -252,7 +251,7 @@ def keys(self):
         """ Retrieve an iterator of attribute types that this Type uses as keys """
         keys_req = RequestBuilder.ConceptMethod.Type.keys()
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.type_keys_iter_res.attributeType),
                    self._tx_service.run_concept_iter_method(self.id, keys_req))
@@ -353,7 +352,7 @@ def roles(self):
         """ Retrieve roles in this relation schema type """
         get_roles = RequestBuilder.ConceptMethod.RelationType.roles()
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.relationType_roles_iter_res.role),
                    self._tx_service.run_concept_iter_method(self.id, get_roles))
@@ -407,7 +406,7 @@ def relations(self):
         """ Retrieve relations that this role participates in, as an iterator """
         relations_req = RequestBuilder.ConceptMethod.Role.relations()
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.role_relations_iter_res.relationType),
                    self._tx_service.run_concept_iter_method(self.id, relations_req))
@@ -416,7 +415,7 @@ def players(self):
         """ Retrieve an iterator of entities that play this role """
         players_req = RequestBuilder.ConceptMethod.Role.players()
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.role_players_iter_res.type),
                    self._tx_service.run_concept_iter_method(self.id, players_req))
@@ -443,7 +442,7 @@ def relations(self, *roles):
         """ Get iterator this Thing's relations, filtered to the optionally provided roles """
         relations_req = RequestBuilder.ConceptMethod.Thing.relations(roles)
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.thing_relations_iter_res.relation),
                    self._tx_service.run_concept_iter_method(self.id, relations_req))
@@ -452,7 +451,7 @@ def attributes(self, *attribute_types):
         """ Retrieve iterator of this Thing's attributes, filtered by optionally provided attribute types """
         attrs_req = RequestBuilder.ConceptMethod.Thing.attributes(attribute_types)
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.thing_attributes_iter_res.attribute),
                    self._tx_service.run_concept_iter_method(self.id, attrs_req))
@@ -461,7 +460,7 @@ def roles(self):
         """ Retrieve iterator of roles this Thing plays """
         roles_req = RequestBuilder.ConceptMethod.Thing.roles()
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.thing_roles_iter_res.role),
                    self._tx_service.run_concept_iter_method(self.id, roles_req))
@@ -470,7 +469,7 @@ def keys(self, *attribute_types):
         """ Retrieve iterator of keys (i.e. actual attributes) of this Thing, filtered by the optionally provided attribute types """
         keys_req = RequestBuilder.ConceptMethod.Thing.keys(attribute_types)
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.thing_keys_iter_res.attribute),
                    self._tx_service.run_concept_iter_method(self.id, keys_req))
@@ -506,7 +505,7 @@ def owners(self):
         """ Retrieve entities that have this attribute value """
         owners_req = RequestBuilder.ConceptMethod.Attribute.owners()
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.attribute_owners_iter_res.thing),
                    self._tx_service.run_concept_iter_method(self.id, owners_req))
@@ -551,7 +550,7 @@ def role_players(self, *roles):
         """ Retrieve role players filtered by roles """
         role_players_req = RequestBuilder.ConceptMethod.Relation.role_players(roles)
         from grakn.service.Session.Concept import ConceptFactory
-        return imap(lambda iter_res:
+        return map(lambda iter_res:
                    ConceptFactory.create_remote_concept(self._tx_service,
                                                         iter_res.relation_rolePlayers_iter_res.thing),
                    self._tx_service.run_concept_iter_method(self.id, role_players_req))

grakn/service/Session/TransactionService.py

@@ -18,15 +18,14 @@
 #
 
 import six
-from six.moves import queue
-
-from itertools import imap
+from six.moves import queue, map
 
 from grakn.service.Session.util.RequestBuilder import RequestBuilder
 import grakn.service.Session.util.ResponseReader as ResponseReader # for circular import issue
 from grakn.service.Session.util import enums
 from grakn.exception.GraknError import GraknError
 
+
 class TransactionService(object):
 
     def __init__(self, session_id, tx_type, transaction_endpoint):
@@ -114,7 +113,7 @@ def run_concept_method(self, concept_id, grpc_concept_method_req):
         return response.conceptMethod_res.response
 
     def run_concept_iter_method(self, concept_id, grpc_concept_iter_method_req):
-        return imap(lambda res: res.conceptMethod_iter_res.response, Iterator(self._communicator, RequestBuilder.start_iterating_concept_method(concept_id, grpc_concept_iter_method_req)))
+        return map(lambda res: res.conceptMethod_iter_res.response, Iterator(self._communicator, RequestBuilder.start_iterating_concept_method(concept_id, grpc_concept_iter_method_req)))
 
     def explanation(self, explainable):
         """ Retrieve the explanation of a Concept Map from the server """

grakn/service/Session/util/ResponseReader.py

@@ -17,19 +17,18 @@
 # under the License.
 #
 
-from itertools import imap
-
 import datetime
 from grakn.service.Session.util import enums
 from grakn.service.Session.Concept import ConceptFactory
-from grakn.exception.GraknError import GraknError 
+from grakn.exception.GraknError import GraknError
+from six.moves import map
 
 
 class ResponseReader(object):
 
     @staticmethod
     def get_query_results(tx_service, iterator):
-        return imap(lambda iterate_res: AnswerConverter.convert(tx_service, iterate_res.query_iter_res.answer), iterator)
+        return map(lambda iterate_res: AnswerConverter.convert(tx_service, iterate_res.query_iter_res.answer), iterator)
 
     @staticmethod
     def get_concept(tx_service, grpc_get_schema_concept):
@@ -55,7 +54,7 @@ def get_schema_concept(tx_service, grpc_get_concept):
 
     @staticmethod
     def get_attributes_by_value(tx_service, iterator):
-        return imap(lambda iterate_res: ConceptFactory.create_remote_concept(tx_service, iterate_res.getAttributes_iter_res.attribute), iterator)
+        return map(lambda iterate_res: ConceptFactory.create_remote_concept(tx_service, iterate_res.getAttributes_iter_res.attribute), iterator)
 
     @staticmethod
     def put_entity_type(tx_service, grpc_put_entity_type):