diff --git a/src/generate.ts b/src/generate.ts
index bf1390d6..d24aaf73 100644
--- a/src/generate.ts
+++ b/src/generate.ts
@@ -6,7 +6,7 @@ import {ENUMERATOR_INDEX} from '../src/enumerator';
 import {QueryConfig, DEFAULT_QUERY_CONFIG} from './config';
 import {SpecQueryModel} from './model';
 import {Property} from './property';
-import {EncodingQuery, ScaleQuery} from './query/encoding';
+import {EncodingQuery} from './query/encoding';
 import {SpecQuery} from './query/spec';
 import {Schema} from './schema';
 import {Dict} from './util';
@@ -37,12 +37,12 @@ export function generate(specQ: SpecQuery, schema: Schema, opt: QueryConfig = DE
         ENCODING_QUERY_INDEX[channel] = specQM.getEncodingQueryByChannel(channel);
       });
 
-      const y_encQ = ENCODING_QUERY_INDEX[Channel.Y];
-      if (y_encQ !== undefined) {
+      const yEncQ = ENCODING_QUERY_INDEX[Channel.Y];
+      if (yEncQ !== undefined) {
         if (ENCODING_QUERY_INDEX[Channel.ROW] ||
-            schema.cardinality(y_encQ) > 10) {
+            schema.cardinality(yEncQ) > 10) {
 
-          if (y_encQ.scale === undefined) {
+          if (yEncQ.scale === undefined) {
             specQM.setEncodingProperty(
               specQM.getEncodingQueryIndexByChannel(Channel.Y),
               Property.SCALE,
@@ -51,7 +51,7 @@ export function generate(specQ: SpecQuery, schema: Schema, opt: QueryConfig = DE
             );
           }
 
-          if (y_encQ.scale) {
+          if (yEncQ.scale) {
             specQM.setEncodingProperty(
               specQM.getEncodingQueryIndexByChannel(Channel.Y),
               Property.SCALE_BANDSIZE,
@@ -62,12 +62,12 @@ export function generate(specQ: SpecQuery, schema: Schema, opt: QueryConfig = DE
         }
       }
 
-      const x_encQ = ENCODING_QUERY_INDEX[Channel.X];
-      if (x_encQ !== undefined) {
+      const xEncQ = ENCODING_QUERY_INDEX[Channel.X];
+      if (xEncQ !== undefined) {
         if (ENCODING_QUERY_INDEX[Channel.COLUMN] ||
-            schema.cardinality(x_encQ) > 10) {
+            schema.cardinality(xEncQ) > 10) {
 
-          if (x_encQ.scale === undefined) {
+          if (xEncQ.scale === undefined) {
             specQM.setEncodingProperty(
               specQM.getEncodingQueryIndexByChannel(Channel.X),
               Property.SCALE,
@@ -76,7 +76,7 @@ export function generate(specQ: SpecQuery, schema: Schema, opt: QueryConfig = DE
             );
           }
 
-          if (x_encQ.scale) {
+          if (xEncQ.scale) {
             specQM.setEncodingProperty(
               specQM.getEncodingQueryIndexByChannel(Channel.X),
               Property.SCALE_BANDSIZE,
@@ -95,11 +95,11 @@ export function generate(specQ: SpecQuery, schema: Schema, opt: QueryConfig = DE
     answerSet = answerSet.map(function(specQM) {
       ENCODING_QUERY_INDEX[Channel.COLOR] = specQM.getEncodingQueryByChannel(Channel.COLOR);
 
-      const color_encQ = ENCODING_QUERY_INDEX[Channel.COLOR];
-      if ((color_encQ !== undefined) && (color_encQ.type === Type.NOMINAL) &&
-          (schema.cardinality(color_encQ) > 10)) {
+      const colorEncQ = ENCODING_QUERY_INDEX[Channel.COLOR];
+      if ((colorEncQ !== undefined) && (colorEncQ.type === Type.NOMINAL) &&
+          (schema.cardinality(colorEncQ) > 10)) {
 
-        if (color_encQ.scale === undefined) {
+        if (colorEncQ.scale === undefined) {
           specQM.setEncodingProperty(
             specQM.getEncodingQueryIndexByChannel(Channel.COLOR),
             Property.SCALE,
@@ -108,7 +108,7 @@ export function generate(specQ: SpecQuery, schema: Schema, opt: QueryConfig = DE
           );
         }
 
-        if (color_encQ.scale) {
+        if (colorEncQ.scale) {
           specQM.setEncodingProperty(
             specQM.getEncodingQueryIndexByChannel(Channel.COLOR),
             Property.SCALE_RANGE,