Increasing line width coloured by y-axis value results in squiggly line

[Michael-Geuenich]

I want to create a line plot coloured by the value of the y-axis and increase its width. Unfortunately increasing the width results in the squiggles shown in the image below:

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Removing either the size or color parameter gets rid of the squiggles. Note that this seems to be a windows specific issue, as it seems to work for others on Mac. I'm on windows 10 and R 4.0.3.

library(tidyverse)

df <- tibble(x = seq(-3, 2.99, by = .01))
df$y <- dnorm(df$x)

ggplot(df, aes(x = x, y = y, color = y )) + 
  geom_line(size = 10)

[karawoo]

When you add a color aesthetic mapped to your y variable, you're plotting different line segments for each y value (a single line segment can't have multiple colors). It's not as pronounced on my machine (mac) but if you look at the top you can see a moire effect indicative of a bunch of close-together lines. You could try increasing the resolution of your data or choosing a different graphics device to see if you get better results that way, but the fundamental issue is going to remain.

library("tidyverse")
set.seed(20)

df <- tibble(x = seq(-3, 2.99, by = .01))
df$y <- dnorm(df$x)

ggplot(df, aes(x = x, y = y, color = y )) + 
  geom_line(size = 10)

^{Created on 2021-10-15 by the reprex package (v2.0.1)}