grid --> false in spy recipe, removed info, added example

src/examples.jl

@@ -318,6 +318,16 @@ PlotExample("Animation with subplots",
     end)]
 ),
 
+PlotExample("Spy",
+    "For a matrix `mat` with unique nonzeros `spy(mat)` returns a colorless plot. If `mat` has various different nonzero values, a colorbar is added. The colorbar can be disabled with `legend = nothing`. As always, the marker shape and size can be changed with `spy(mat, markersize = 5, markershape = :diamond)`",
+    [:(begin
+    a = spdiagm((ones(200), ones(199), ones(199), ones(150), ones(150)),(0, 1, -1, 50, -50))
+    n = 20
+    b = [i > j ? i * j : 0 for i in 1:n, j in 1:n]
+    plot(spy(a), spy(b, markersize = 5, markershape = :diamond), title = ["Unique nonzeros" "Different nonzeros"], yguide = "Row", xguide = "Column")
+    end)]
+),
+
 ]
 
 # ---------------------------------------------------------------------------------

src/recipes.jl

@@ -976,6 +976,9 @@ end
     @assert length(g.args) == 1 && typeof(g.args[1]) <: AbstractMatrix
     seriestype := :spy
     mat = g.args[1]
+    if length(unique(mat)) <= 2
+        legend --> nothing
+    end
     n,m = size(mat)
     Plots.SliceIt, 1:m, 1:n, Surface(mat)
 end
@@ -990,7 +993,6 @@ end
         markershape := :circle
     end
     if d[:markersize] == default(:markersize)
-        info("In the spy recipe the default markersize is 1. If you are viewing a small matrix, you may consider increasing it with the markersize attribute.")
         markersize := 1
     end
     markerstrokewidth := 0
@@ -1000,6 +1002,7 @@ end
     y := rs
     z := nothing
     seriestype := :scatter
+    grid --> false
     ()
 end