add a dimensionalty check

src/backends/pgfplotsx.jl

@@ -72,8 +72,11 @@ function surface_to_vecs(x::AVec, y::AVec, s::Union{AMat,Surface})
     yn = Vector{eltype(y)}(undef, length(a))
     zn = Vector{eltype(s)}(undef, length(a))
     for (n, (i, j)) in enumerate(Tuple.(CartesianIndices(a)))
-        xn[n] = x[i]
-        yn[n] = y[j]
+        if length(x) == size(s)[1]
+            i, j = j, i
+        end
+        xn[n] = x[j]
+        yn[n] = y[i]
         zn[n] = a[i, j]
     end
     return xn, yn, zn