diff --git a/src/lib/search.js b/src/lib/search.js
index 738864f330d..c85ed5f975d 100644
--- a/src/lib/search.js
+++ b/src/lib/search.js
@@ -62,9 +62,7 @@ exports.sorterDes = function(a, b) { return b - a; };
  * just be off by a rounding error
  * return the distinct values and the minimum difference between any two
  */
-exports.distinctVals = function(valsIn, opts) {
-    var unitMinDiff = (opts || {}).unitMinDiff;
-
+exports.distinctVals = function(valsIn) {
     var vals = valsIn.slice();  // otherwise we sort the original array...
     vals.sort(exports.sorterAsc); // undefined listed in the end - also works on IE11
 
@@ -73,9 +71,7 @@ exports.distinctVals = function(valsIn, opts) {
         if(vals[last] !== BADNUM) break;
     }
 
-    var minDiff = 1;
-    if(!unitMinDiff) minDiff = (vals[last] - vals[0]) || 1;
-
+    var minDiff = (vals[last] - vals[0]) || 1;
     var errDiff = minDiff / (last || 1) / 10000;
     var newVals = [];
     var preV;
diff --git a/src/traces/bar/cross_trace_calc.js b/src/traces/bar/cross_trace_calc.js
index 00e14812244..f1cad80924d 100644
--- a/src/traces/bar/cross_trace_calc.js
+++ b/src/traces/bar/cross_trace_calc.js
@@ -172,7 +172,7 @@ function setGroupPositionsInOverlayMode(pa, sa, calcTraces, opts) {
         var calcTrace = calcTraces[i];
 
         var sieve = new Sieve([calcTrace], {
-            unitMinDiff: opts.xCat || opts.yCat,
+            posAxis: pa,
             sepNegVal: false,
             overlapNoMerge: !opts.norm
         });
@@ -196,6 +196,7 @@ function setGroupPositionsInOverlayMode(pa, sa, calcTraces, opts) {
 
 function setGroupPositionsInGroupMode(gd, pa, sa, calcTraces, opts) {
     var sieve = new Sieve(calcTraces, {
+        posAxis: pa,
         sepNegVal: false,
         overlapNoMerge: !opts.norm
     });
@@ -205,7 +206,7 @@ function setGroupPositionsInGroupMode(gd, pa, sa, calcTraces, opts) {
 
     // relative-stack bars within the same trace that would otherwise
     // be hidden
-    unhideBarsWithinTrace(sieve);
+    unhideBarsWithinTrace(sieve, pa);
 
     // set bar bases and sizes, and update size axis
     if(opts.norm) {
@@ -218,6 +219,7 @@ function setGroupPositionsInGroupMode(gd, pa, sa, calcTraces, opts) {
 
 function setGroupPositionsInStackOrRelativeMode(gd, pa, sa, calcTraces, opts) {
     var sieve = new Sieve(calcTraces, {
+        posAxis: pa,
         sepNegVal: opts.mode === 'relative',
         overlapNoMerge: !(opts.norm || opts.mode === 'stack' || opts.mode === 'relative')
     });
@@ -610,7 +612,7 @@ function sieveBars(sieve) {
     }
 }
 
-function unhideBarsWithinTrace(sieve) {
+function unhideBarsWithinTrace(sieve, pa) {
     var calcTraces = sieve.traces;
 
     for(var i = 0; i < calcTraces.length; i++) {
@@ -619,6 +621,7 @@ function unhideBarsWithinTrace(sieve) {
 
         if(fullTrace.base === undefined) {
             var inTraceSieve = new Sieve([calcTrace], {
+                posAxis: pa,
                 sepNegVal: true,
                 overlapNoMerge: true
             });
diff --git a/src/traces/bar/sieve.js b/src/traces/bar/sieve.js
index 14e994f34a1..ad7eec482f8 100644
--- a/src/traces/bar/sieve.js
+++ b/src/traces/bar/sieve.js
@@ -40,14 +40,17 @@ function Sieve(traces, opts) {
     }
     this.positions = positions;
 
-    var dv = distinctVals(positions, {
-        unitMinDiff: opts.unitMinDiff
-    });
+    var dv = distinctVals(positions);
 
     this.distinctPositions = dv.vals;
     if(dv.vals.length === 1 && width1 !== Infinity) this.minDiff = width1;
     else this.minDiff = Math.min(dv.minDiff, width1);
 
+    var type = (opts.posAxis || {}).type;
+    if(type === 'category' || type === 'multicategory') {
+        this.minDiff = 1;
+    }
+
     this.binWidth = this.minDiff;
 
     this.bins = {};
diff --git a/src/traces/box/calc.js b/src/traces/box/calc.js
index f08e80f8713..2b810f07679 100644
--- a/src/traces/box/calc.js
+++ b/src/traces/box/calc.js
@@ -40,7 +40,7 @@ module.exports = function calc(gd, trace) {
     var allPosArrays = getPosArrays(trace, posLetter, posAxis, fullLayout[numKey]);
     var posArray = allPosArrays[0];
     var origPos = allPosArrays[1];
-    var dv = Lib.distinctVals(posArray);
+    var dv = Lib.distinctVals(posArray, posAxis);
     var posDistinct = dv.vals;
     var dPos = dv.minDiff / 2;
 
diff --git a/src/traces/box/cross_trace_calc.js b/src/traces/box/cross_trace_calc.js
index 34eb60528ac..00632d0dbb2 100644
--- a/src/traces/box/cross_trace_calc.js
+++ b/src/traces/box/cross_trace_calc.js
@@ -60,9 +60,10 @@ function setPositionOffset(traceType, gd, boxList, posAxis) {
     if(!pointList.length) return;
 
     // box plots - update dPos based on multiple traces
-    var boxdv = Lib.distinctVals(pointList, {
-        unitMinDiff: posAxis.type === 'category' || posAxis.type === 'multicategory'
-    });
+    var boxdv = Lib.distinctVals(pointList);
+    if(posAxis.type === 'category' || posAxis.type === 'multicategory') {
+        boxdv.minDiff = 1;
+    }
 
     var dPos0 = boxdv.minDiff / 2;
 
diff --git a/test/jasmine/tests/bar_test.js b/test/jasmine/tests/bar_test.js
index 62d74d99d71..3379549953c 100644
--- a/test/jasmine/tests/bar_test.js
+++ b/test/jasmine/tests/bar_test.js
@@ -981,12 +981,10 @@ describe('Bar.crossTraceCalc (formerly known as setPositions)', function() {
 
     it('should set unit width for categories in overlay mode', function() {
         var gd = mockBarPlot([{
-            type: 'bar',
             x: ['a', 'b', 'c'],
             y: [2, 2, 2]
         },
         {
-            type: 'bar',
             x: ['a', 'c'],
             y: [1, 1]
         }], {
@@ -996,6 +994,20 @@ describe('Bar.crossTraceCalc (formerly known as setPositions)', function() {
         expect(gd.calcdata[1][0].t.bardelta).toBe(1);
     });
 
+    it('should set unit width for categories case of missing data for defined category', function() {
+        var gd = mockBarPlot([{
+            x: ['a', 'c'],
+            y: [1, 2]
+        }, {
+            x: ['a', 'c'],
+            y: [1, 2],
+        }], {
+            xaxis: { categoryarray: ['a', 'b', 'c'] }
+        });
+
+        expect(gd.calcdata[1][0].t.bardelta).toBe(1);
+    });
+
     describe('should relative-stack bar within the same trace that overlap under barmode=group', function() {
         it('- base case', function() {
             var gd = mockBarPlot([{