warning and hint on mismatched attr lengths

src/utils.jl

@@ -82,8 +82,8 @@ function series_segments(series::Series, seriestype::Symbol = :path)
     args = RecipesPipeline.is3d(series) ? (x, y, z) : (x, y)
     nan_segments = collect(iter_segments(args...))
 
-    if has_attribute_segments(series)
-        return Iterators.flatten(map(nan_segments) do r
+    result = if has_attribute_segments(series)
+        Iterators.flatten(map(nan_segments) do r
             if seriestype in (:scatter, :scatter3d)
                 (SeriesSegment(i:i, i) for i in r)
             else
@@ -91,8 +91,28 @@ function series_segments(series::Series, seriestype::Symbol = :path)
             end 
         end)
     else
-        return (SeriesSegment(r, 1) for r in nan_segments)
+        (SeriesSegment(r, 1) for r in nan_segments)
     end 
+
+    seg_attr_range = UnitRange(minimum(first(seg.range) for seg in result),
+                                maximum(last(seg.range) for seg in result))
+    for attr in _segmenting_vector_attributes
+        v = get(series, attr, nothing)
+        if v isa AVec && eachindex(v) != seg_attr_range
+            @warn "Indices $(eachindex(v)) of attribute `$attr` does not match data indices $seg_attr_range."
+            if any(v -> !isnothing(v) && any(isnan, v), (x,y,z))
+                @info """Data contains NaNs or missing values, and indices of `$attr` vector do not match data indices.
+                    If you intend elements of `$attr` to apply to individual NaN-separated segements in the data,
+                    pass each segment in a separate vector instead, and use a row vector for `$attr`. Legend entries 
+                    may be suppressed by passing an empty label.
+                    For example,
+                        plot([1:2,1:3], [[4,5],[3,4,5]], label=["y" ""], $attr=[1 2])
+                    """
+            end
+        end
+    end
+
+    return result
 end
 
 # helpers to figure out if there are NaN values in a list of array types
@@ -577,15 +597,7 @@ function get_markerstrokewidth(series, i::Int = 1)
     _cycle(series[:markerstrokewidth], i)
 end
 
-function has_attribute_segments(series::Series)
-    # we want to check if a series needs to be split into segments just because
-    # of its attributes
-    series[:seriestype] == :shape && return false
-    # check relevant attributes if they have multiple inputs
-    return any(
-        (typeof(series[attr]) <: AbstractVector && length(series[attr]) > 1)
-        for
-        attr in [
+const _segmenting_vector_attributes = (
     :seriescolor,
     :seriesalpha,
     :linecolor,
@@ -601,10 +613,18 @@ function has_attribute_segments(series::Series)
     :markerstrokealpha,
     :markerstrokewidth,
     :markershape,
-        ]
-    ) || any(
-        typeof(series[attr]) <: AbstractArray for attr in (:line_z, :fill_z, :marker_z)
 )
+
+const _segmenting_array_attributes = (:line_z, :fill_z, :marker_z)
+
+function has_attribute_segments(series::Series)
+    # we want to check if a series needs to be split into segments just because
+    # of its attributes
+    series[:seriestype] == :shape && return false
+    # check relevant attributes if they have multiple inputs
+    return any(series[attr] isa AbstractVector && length(series[attr]) > 1
+                for attr in _segmenting_vector_attributes
+        ) || any(series[attr] isa AbstractArray for attr in _segmenting_array_attributes)
 end
 
 function get_aspect_ratio(sp)