Take the 2-minute tour ×
Mathematica Stack Exchange is a question and answer site for users of Mathematica. It's 100% free, no registration required.

I'm running Mathematica version 9. I am using ListPlot to plot two sets of data. For each data set, I am using different PlotMarkers: for the first data set, I use red disks, while for the second data set, I use red rectangles. To do this, I define Graphics objects redDisk and redRectangle as shown below. (I have found that it is necessary to define nonzero ImagePadding to prevent the edges of the Graphics from being cut off.)

Next, I want to display a plot legend describing the two different PlotMarkers. To do this, I want to use the PlotLegends option that is newly implemented in Mathematica version 9. I define a PointLegend called legend. Within PointLegend, I use pass in the objects redDisk and redRectangle to the LegendMarkers option. Then I give legend to the PlotLegends option of ListPlot and use the Placed function to position the legend in the plot.

The code to do all of this is the following:

(* Define PlotMarkers *)
pm = 8; (* size of PlotMarkers *)
redDisk = 
  Graphics[{Red, Disk[]}, ImageSize -> (pm + 2), 
   ImagePadding -> {{1, 1}, {1, 1}}];
redRectangle = 
  Graphics[{Red, Rectangle[]}, ImageSize -> (pm + 1), 
   ImagePadding -> {{1, 1}, {1, 1}}];

(* Define a PointLegend using the PlotMarkers defined above *)
legend = PointLegend[{Red, Red}, {"red disk", "red rectangle"}, 
   LabelStyle -> {18, FontFamily -> "Arial"}, 
   LegendFunction -> "Frame", 
   LegendMarkers -> {redDisk, redRectangle}];

(* Create some data to plot *)
myRange = Range[0, 2 Pi, 0.175];
diskData = Transpose[{myRange, Sin[myRange]}];
rectangleData = Transpose[{myRange, Cos[myRange]}];

(* Plot the data *)
myPlot = ListPlot[
  {diskData, rectangleData}, PlotRange -> All, Frame -> True, 
  FrameLabel -> {"x", "y"}, BaseStyle -> {18, FontFamily -> "Arial"}, 
  PlotStyle -> Red, PlotMarkers -> {redDisk, redRectangle}, 
  ImageSize -> 500,
  PlotLegends -> Placed[legend, Scaled[{0.65, 0.85}]]
  ]

which gives this output:

SmallGraphic

However, when I zoom in on this graphical output, I see that the markers inside the PointLegend do not appear exactly the same as the PlotMarkers of ListPlot. Specifically, the markers inside the PointLegend appear to have a strange gray edge or border:

ZoomGraphic

where I used the Mathematica front end's magnification feature to zoom in on the myPlot graphical output.

The strange gray edges/borders persist even when I export myPlot to, for example, a pdf file:

(* Export the data as a pdf file *)
Export["example.pdf", myPlot]

When I open example.pdf in a pdf viewer and zoom in, I see the following. The strange gray edges/borders are still apparent in the LegendMarkers within the legend:

PDFGraphic

So, my question is, how can I remove the gray edges/borders of the LegendMarkers so that the LegendMarkers and PlotMarkers look the same?

Thanks for your time.

share|improve this question
add comment

1 Answer

up vote 8 down vote accepted

Instead of simply using Red as the directive, set the face and edge colors explicitly so that there is no ambiguity. If you use FaceForm@Red and EdgeForm@Red (or None) in your definitions for redDisk and redRectangle, you get legend markers without black borders.

share|improve this answer
    
Thanks so much! This may justify or require a separate question, but is there any way to force the LegendMarkers to be the same size as the PlotMarkers? In the plot, it looks like the redDisk PlotMarkers are somewhat larger than the redDisk LegendMarkers. –  Andrew Oct 19 '13 at 17:09
1  
Yes, it should be possible. Off the top of my head, the solution is to use {redDisk, size} in the plot marker and legend marker option. However, the value of size is typically a fraction of the size of the parent figure (e.g. 0.04). Since your legend and plot figures are of different sizes, the value you choose for size in each must be so that the disks look the same for both plots. I don't have the time right now to work on it and write up an automated solution, but this is probably sufficient info for you to manually tweak them for now. Also, I suppose there might be a question here... –  rm -rf Oct 19 '13 at 17:36
    
Thanks. This helps a lot! Yes, it seems that there might be a question here, too. Thanks again. –  Andrew Oct 19 '13 at 17:49
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.