Merge pull request #1547 from wfrgra/round_axis_limits

allow automatic widening of the axis limits to the next power of 10 …

src/arg_desc.jl

@@ -110,7 +110,7 @@ const _arg_desc = KW(
 
 # axis args
 :guide     				  => "String. Axis guide (label).",
-:lims      				  => "NTuple{2,Number}. Force axis limits.  Only finite values are used (you can set only the right limit with `xlims = (-Inf, 2)` for example).",
+:lims      				  => "NTuple{2,Number} or Symbol. Force axis limits.  Only finite values are used (you can set only the right limit with `xlims = (-Inf, 2)` for example). `:round` widens the limit to the nearest round number ie. [0.1,3.6]=>[0.0,4.0]",
 :ticks     				  => "Vector of numbers (set the tick values), Tuple of (tickvalues, ticklabels), or `:auto`",
 :scale     				  => "Symbol. Scale of the axis: `:none`, `:ln`, `:log2`, `:log10`",
 :rotation  				  => "Number. Degrees rotation of tick labels.",

src/axes.jl

@@ -441,6 +441,13 @@ function default_should_widen(axis::Axis)
     should_widen
 end
 
+function round_limits(amin,amax)
+    scale = 10^(1-round(log10(amax - amin)))
+    amin = floor(amin*scale)/scale
+    amax = ceil(amax*scale)/scale
+    amin, amax
+end
+
 # using the axis extrema and limit overrides, return the min/max value for this axis
 function axis_limits(axis::Axis, should_widen::Bool = default_should_widen(axis))
     ex = axis[:extrema]
@@ -471,6 +478,8 @@ function axis_limits(axis::Axis, should_widen::Bool = default_should_widen(axis)
         end
     elseif should_widen
         widen(amin, amax)
+    elseif lims == :round
+        round_limits(amin,amax)
     else
         amin, amax
     end