From 1e4eb0105942debe27079174bd284bad5b1824f4 Mon Sep 17 00:00:00 2001
From: bigbenhur <benhur@alpenjodel.de>
Date: Fri, 3 Jun 2016 15:54:14 +0200
Subject: [PATCH] Support auto grid min/max when using log scale, Issue #3090

---
 public/app/plugins/panel/graph/graph.js       | 58 ++++++++++---------
 .../plugins/panel/graph/specs/graph_specs.ts  |  6 +-
 2 files changed, 34 insertions(+), 30 deletions(-)

diff --git a/public/app/plugins/panel/graph/graph.js b/public/app/plugins/panel/graph/graph.js
index 86ad3b5f025..8019a51354b 100755
--- a/public/app/plugins/panel/graph/graph.js
+++ b/public/app/plugins/panel/graph/graph.js
@@ -373,42 +373,46 @@ function (angular, $, moment, _, kbn, GraphTooltip) {
           if (axis.logBase === 1) {
             return;
           }
+          if (axis.min < Number.MIN_VALUE) {
+            axis.min = null;
+          }
 
           var series, i;
-          var max = axis.max;
+          var max = axis.max, min = axis.min;
 
-          if (max === null) {
-            for (i = 0; i < data.length; i++) {
-              series = data[i];
-              if (series.yaxis === axis.index) {
-                if (max < series.stats.max) {
-                  max = series.stats.max;
-                }
+          for (i = 0; i < data.length; i++) {
+            series = data[i];
+            if (series.yaxis === axis.index) {
+              if (max === null || max < series.stats.max) {
+                max = series.stats.max;
+              }
+              if (min === null || min > series.stats.min) {
+                min = series.stats.min;
               }
             }
-            if (max === void 0) {
-              max = Number.MAX_VALUE;
-            }
+          }
+          if (max === null && min === null) {
+            max = Math.pow(axis.logBase,+2);
+            min = Math.pow(axis.logBase,-2);
+          } else if (max === null) {
+            max = min*Math.pow(axis.logBase,+4);
+          } else if (min === null) {
+            min = max*Math.pow(axis.logBase,-4);
           }
 
-          axis.min = axis.min !== null ? axis.min : 0;
-          axis.ticks = [0, 1];
-          var nextTick = 1;
+          axis.transform = function(v) { return Math.log(v) / Math.log(axis.logBase); };
+          axis.inverseTransform  = function (v) { return Math.pow(axis.logBase,v); };
 
-          while (true) {
-            nextTick = nextTick * axis.logBase;
+          min = axis.inverseTransform(Math.floor(axis.transform(min)));
+          max = axis.inverseTransform(Math.ceil(axis.transform(max)));
+
+          axis.min = axis.min !== null ? axis.min : min;
+          axis.max = axis.max !== null ? axis.max : max;
+
+          axis.ticks = [];
+          var nextTick;
+          for (nextTick = min; nextTick <= max; nextTick *= axis.logBase) {
             axis.ticks.push(nextTick);
-            if (nextTick > max) {
-              break;
-            }
-          }
-
-          if (axis.logBase === 10) {
-            axis.transform = function(v) { return Math.log(v+0.1); };
-            axis.inverseTransform  = function (v) { return Math.pow(10,v); };
-          } else {
-            axis.transform = function(v) { return Math.log(v+0.1) / Math.log(axis.logBase); };
-            axis.inverseTransform  = function (v) { return Math.pow(axis.logBase,v); };
           }
         }
 
diff --git a/public/app/plugins/panel/graph/specs/graph_specs.ts b/public/app/plugins/panel/graph/specs/graph_specs.ts
index b9c9362e5de..b383a31a976 100644
--- a/public/app/plugins/panel/graph/specs/graph_specs.ts
+++ b/public/app/plugins/panel/graph/specs/graph_specs.ts
@@ -172,9 +172,9 @@ describe('grafanaGraph', function() {
 
     it('should apply axis transform and ticks', function() {
       var axis = ctx.plotOptions.yaxes[0];
-      expect(axis.transform(100)).to.be(Math.log(100+0.1));
-      expect(axis.ticks[0]).to.be(0);
-      expect(axis.ticks[1]).to.be(1);
+      expect(axis.transform(100)).to.be(Math.log(100)/Math.log(10));
+      expect(axis.ticks[0]).to.be(0.01);
+      expect(axis.ticks[1]).to.be(0.1);
     });
   });