Remove incorrect coloured outline from ggplot legend in plots using multiple dataframes?

Question

I've created a ggplot out of multiple dataframes. One of the dataframes is used to draw filled polygons/rectangles while the other is used to create contour plots. If I specify a colour in the contour plot element, it appears as an outline in the legend for the polygons (but not as an outline for the plotted polygons themselves).

How can I remove the outline only from the single unrelated legend element?

Reproducible example:

df1 <- data.frame(
    person = c("Avery", "Doug", "Avery", "Doug", "Avery", "Doug", "Avery", "Doug"),
    place = c("A","A","B","B","C","C","D","D"),
    Coord1 = c(10, 30, 70, 90, 70, 90, 10, 30),
    Coord2 = c(70, 90, 70, 90, 10, 30, 10, 30)
    )

df2 <- structure(list(place = c("A", "A", "A", "A", "A", "A", "A", "A", 
"A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", 
"A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", 
"A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", 
"A", "A", "A", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", 
"B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", 
"B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", 
"B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", 
"B", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", 
"C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", 
"C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", 
"C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "D", 
"D", "D", "D", "D", "D", "D", "D", "D", "D", "D", "D", "D", "D", 
"D", "D", "D", "D", "D", "D", "D", "D", "D", "D", "D", "D", "D", 
"D", "D", "D", "D", "D", "D", "D", "D", "D", "D", "D", "D", "D", 
"D", "D", "D", "D", "D", "D", "D", "D", "D", "D"), Coord1 = c(11.9321233389815, 
5.65317891793307, 19.1326709658932, 27.9338809206353, 19.9660510683355, 
21.0749048744809, 7.21913717149466, 20.1920548762508, 10.4543717875714, 
25.757795926256, 12.1828845087838, -0.465353420455905, 7.11311351850768, 
14.8155028526132, -2.1637642702189, 13.0813689628972, 4.7982168502595, 
5.57686199262573, 4.00687188024056, 22.9457782880066, 18.3539124739061, 
4.33984900298331, 17.8841935003471, -1.65929325512088, 4.69179993740943, 
42.6151590341647, 27.615643609024, 10.0218739210389, 37.0107595807328, 
42.2081901427891, 21.4907606643235, 24.3639224345837, 32.772343673693, 
39.707188961395, 39.526308329454, 26.0304665678886, 29.9780452839205, 
26.3307539307013, 30.3989518780307, 48.3076387197071, 18.9469498637539, 
20.2952072925756, 16.6669862005188, 37.4700660304315, 17.8662145857614, 
37.2600750819877, 25.7007521883461, 28.6742428655807, 40.314957702891, 
30.0697139406434, 73.6583322470224, 79.3142178409643, 50.9322840242791, 
70.5198852398892, 61.5150022794989, 66.3183258649759, 76.2469408002744, 
82.2025917335132, 47.6021718929377, 66.3132462976689, 69.1291434239167, 
83.4197156933065, 86.9407992718112, 76.4950208109435, 73.661826873959, 
66.9162963609677, 75.1456713179674, 60.9887903971435, 71.9565881057142, 
68.4266063305417, 57.6911530548141, 74.7773517795878, 69.6101844803799, 
67.790228250546, 69.3010177449088, 102.70586821213, 70.9690781293641, 
81.8211641205855, 89.1142208240172, 103.752341186373, 89.5593092939362, 
80.6305724472789, 82.0007363853625, 65.8943427952359, 78.3936032524407, 
83.0803062787287, 92.1760929466364, 78.9701119884041, 86.8932236845231, 
97.1763793934393, 84.058342477451, 93.7849946833988, 83.1484361525486, 
80.1491902221492, 85.9961991961048, 93.2550659070971, 78.3156355536891, 
94.2129927101896, 93.4865526165191, 93.4934076661858, 75.4629285622502, 
47.6731852393923, 72.88284171046, 75.438344587857, 58.0801523419401, 
69.8230768794789, 60.5302214082446, 65.9778757219936, 70.5612025149866, 
68.4370521177005, 58.1149422572855, 82.8226830631184, 65.7390566694014, 
65.6285158427551, 64.1736763473425, 93.616329884223, 60.1827131711359, 
48.6282110427849, 66.7586165042503, 75.5318338818184, 67.3206665449225, 
59.0440215809036, 51.0189160405021, 84.6055490872487, 54.892120364794, 
97.5277806090821, 87.3463009673921, 102.066058009738, 82.0203143022486, 
90.9586925853003, 88.6949600210823, 103.884302040987, 87.4998069331291, 
76.3591677407161, 81.8943250717613, 100.824382142449, 102.946636154418, 
81.8333852359431, 94.7599932319231, 93.7316328376966, 79.8039952376426, 
92.3881270619707, 71.2558895720234, 99.8119134521082, 112.401228355728, 
83.0814548497863, 94.0539152929977, 79.4016592347326, 85.7829067433969, 
75.948295755515, 3.73649805560632, 23.0903794794387, 8.67023149246646, 
-6.07704226517408, -3.07641645158295, 9.54851319649848, 17.8889045992558, 
5.10657758386499, 18.7016029853773, 25.4522147195668, 6.8023795377009, 
15.3767651131782, 20.3683653225209, -20.3254139776893, 15.6691879496879, 
9.45068374562864, 18.7361628847212, 12.623384426461, 10.17849269891, 
-16.9581826824957, 17.4909319409575, 9.44644950565353, -5.38702617407262, 
6.21805297402208, 14.1749418466783, 12.9105548124602, 27.1855440225952, 
29.8482741922039, 29.7496920817558, 38.524389832422, 33.7023405759537, 
45.3217768361544, 40.1308769909943, 34.4402395511235, 25.068583150376, 
26.2353756696678, 21.8111750232141, 33.8629499457315, 29.7131703823705, 
34.1556614684988, 34.1245105271038, 18.3147946286069, 27.3066155417929, 
26.5207184421978, 34.0884687114446, 26.639481645307, 38.6173778182637, 
37.8098024973006, 13.0741049202031, 45.5358046032432), Coord2 = c(69.9894126325745, 
64.8743763485989, 82.4286751251657, 63.3941714859759, 71.6662421480457, 
64.4679475985789, 70.9818141479016, 58.5333414006127, 57.5007274347188, 
67.978883174351, 71.7750032484243, 83.0764732083471, 56.5706459545147, 
78.6108303958077, 72.3287500312082, 80.4225709350104, 83.2909825415992, 
79.4595795345076, 60.1437449584155, 57.8413316685676, 53.7079406423028, 
70.9231623851271, 69.7788257690901, 75.1347791237738, 67.7044636198011, 
94.3340903929599, 102.873693143552, 65.8173572622545, 76.2734860629939, 
85.2060002479906, 90.1101352051085, 96.2874409924653, 109.760633210447, 
94.6155820846595, 95.2601614162185, 69.4981680111657, 84.4916642548314, 
84.207250490172, 95.2814397728582, 88.6024629127233, 105.45937855117, 
101.73736873413, 96.3994065298907, 89.5148162082444, 85.656552291334, 
87.1768687739584, 103.397297430617, 100.466406474931, 97.492149943699, 
95.7799794375843, 58.689787023173, 91.7856309013427, 70.284597504488, 
82.5264495002628, 72.563622499658, 67.9271039063317, 76.9752642043184, 
77.0427295652995, 60.493215584824, 71.9177768464766, 85.2536338000138, 
78.6037513000414, 79.9167528070661, 45.2538960490244, 73.7270619632537, 
74.1775039120291, 79.3753619281975, 72.5802290852752, 77.6589441840394, 
65.0442876775209, 75.9474471250248, 67.6324983845202, 66.7269504282668, 
61.4684933637993, 84.9370241657568, 100.807408193669, 90.6253499380336, 
82.4392258080415, 85.978657057683, 85.5556977940698, 80.0069018830692, 
92.0205306026153, 92.2799374212157, 92.075887951686, 84.046647740422, 
95.2469867954641, 90.4378832940894, 103.868141681032, 96.1678027516943, 
97.556915790983, 75.8136031118073, 87.269403250105, 102.176170079899, 
83.303319611484, 77.0422898434913, 94.9522487152654, 93.5056368803038, 
99.6066565241826, 93.2540063907868, 75.3235503045194, 4.79683173913879, 
-1.77333441979239, 22.2927646778249, 21.2002682830845, 9.2462559574228, 
12.9328717922413, 9.71104299233956, 6.02183609528862, 16.5548144989934, 
14.9138467115507, 26.4290598776307, 13.2859100121563, 24.6139296632551, 
6.01920473648369, 6.44403579988305, 15.0356163044265, 14.0083469209857, 
-0.983183926446912, 11.305792234271, 17.6465875981944, -8.94856332381213, 
7.36961719889383, 7.92121709811615, -0.418766330916343, -5.42220613778122, 
33.1278663709957, 22.5146385498018, 46.6482380411691, 21.1315055557743, 
23.3535222367336, 37.0589046029771, 20.5508910389587, 34.3154424989857, 
37.5906644856971, 28.9704448512218, 30.6411807554989, 35.4051444540154, 
30.0311466912122, 28.7535914372174, 28.4106840578911, 36.8662136858688, 
12.898132148862, 46.7570642830409, 30.8475454612592, 19.28210909481, 
19.5978468800625, 34.6039683478465, 21.0831790287953, 34.2925742059241, 
53.7786968993373, 19.0172370755723, 9.21397428746006, -2.37886313478754, 
6.79453923040543, 22.6413009302484, 33.2099355799597, 6.58849285636098, 
-11.7836723204909, 5.86738511098067, 3.81888634358306, 20.5825579992258, 
9.8827774793369, 14.4441862792073, 12.3532766231854, 10.2334773998435, 
22.8131908769118, 23.8680133376392, 9.59780868195676, 24.4068082968655, 
11.2009206443726, 13.4244085452577, 22.0625356242069, 12.2526091738859, 
-2.39754291555823, 2.00084520595361, 36.7097665883357, 16.9122643222195, 
20.0379767031296, 41.4658882877744, 24.0612860080661, 24.7786616325539, 
33.9205960391195, 32.0684115690426, 26.5208653130137, 47.3248746356669, 
37.8352815877295, 42.4135950414131, 33.8021211637222, 28.309616360779, 
24.4645546802529, 32.9897820259554, 17.8194684139265, 36.2084800081616, 
37.6500899883031, 22.4961071408182, 47.6368585912597, 57.0362400846021, 
43.7894593761563, 23.2634280784332, 54.7477709366998)), row.names = c(NA, 
-200L), class = c("tbl_df", "tbl", "data.frame"))

ggplot() +
      stat_density_2d(data = df2, 
                    aes(x = Coord1, y = Coord2, group=place, shape="Yuki"),
                    geom = "polygon", contour = TRUE, colour="darkorchid3", bins = 7, alpha=0.2, show.legend=TRUE) +
  geom_polygon(data = df1, aes(x = Coord1, y = Coord2, fill = person), alpha = 0.6) +
  geom_point(data = df1, aes(x = Coord1, y = Coord2), size = 1.5, show.legend=FALSE) +
  geom_text_repel(data = df1, aes(x = Coord1, y = Coord2, label = place), colour="black") +
  ggtitle("Combined Plot", subtitle = "Avery, Doug, Yuki") +
  labs(fill = "Person", shape = "") +
  guides(shape = guide_legend(order = 2), fill = guide_legend(order = 1))

The above code produces this plot:

imgdesc: a ggplot generated from the cold listed above, representing two filled rectangles and a collection of contour plots

This is what I'd like it to look like (moving the second element up or otherwise combining the legends would be awesome, but is a little outside the scope of my question.)

imgdesc: A plot similar to the one generated by the code above, except the purple outline around two of the three legend elements has been removed. The space between the elements is also even.

Things I've tried: rearranging the elements, forcing other colours to be called in the geom_polygon, and using extra elements to try and cover up the outline. The closest I've achieved, is removing the "colour" code from stat_density_2d removes the outline from all the elements in the legend, but it also removes the contour lines from the plot itself, which is not ideal. Removing the "dummy" shape aes from stat_density_2d removes the contour plots from the legend but does not remove the outlines from the other legend elements. Combining the dataframes is also not an ideal/workable solution in this case (sorry).

My actual plots also use custom scale_colour and fill values, which can't be easily included in a minimum reproducible example. For that reason, I haven't gone very far in trying to utilize custom labelling assigned to those, and would appreciate if there's a solution that doesn't depend on scale_color_manual, etc. However, I also know beggers can't be choosers and I'd appreciate any help on this at all!

Sinh Nguyen Sinh Nguyen · Accepted Answer · 2021-01-18T02:08:15

Put the legend in correct layout but it seem really tricky to do anything regard the border. In stead of using your color I use the white color which still distinctive but would not show on legend border.

fill_color <- c("green", "red", "#444444")
names(fill_color) <- c("Avery", "Doug", "Yuki")
line_color <- c("green", "red", "darkorchid3")
names(line_color) <- c("Avery", "Doug", "Yuki")


ggplot() +
  stat_density_2d(data = df2, 
                  # Here using the fill aes instead of shape aes like your
                  # original input which cause the legend was put into 
                  # two different categories. 
                  aes(x = Coord1, y = Coord2, group=place, fill = "Yuki", color="Yuki",),
                  geom = "polygon", contour = TRUE,
                  bins = 7, alpha=0.2, show.legend=TRUE) +
  geom_polygon(data = df1, aes(x = Coord1, y = Coord2, fill = person, color = person),
               colour = "transparent", alpha = 0.6) +
  geom_point(data = df1, aes(x = Coord1, y = Coord2), size = 1.5,
             show.legend=FALSE) +
  geom_text_repel(data = df1, aes(x = Coord1, y = Coord2, label = place),
                  colour="black") +
  ggtitle("Combined Plot", subtitle = "Avery, Doug, Yuki") +
  scale_color_manual(values = line_color, guide = FALSE) +
  scale_fill_manual(values = fill_color) + 
  labs(fill = "Person", shape = "") +
  guides(shape = guide_legend(order = 2), fill = guide_legend(order = 1)) +
  theme(legend.key = element_rect(fill = NA))

[Update with maniputlate color pallete using scale_fill_manual and scale_color_manual]

Remove incorrect coloured outline from ggplot legend in plots using multiple dataframes?

1 Answers