ggplot line plot: is there a way to depict the data points under or over the line plot depending on what looks better?

Question

I wanted to create a line plot based on the data MIA_YEAR. It already looks quite good but I want to move those data points under the plot that (almost) touch the line. Or in mathematial terms: If the slope increases the data points should be under the line plot and if the slope decreases the data points should be over the plot instead of having all data points over the line. that is how it looks like until now -->.

MIA_Year %>%
  ggplot(aes(x = YEAR, y = Percent)) +
  geom_line(group=1, color = "steelblue", linewidth = 1) + #group = 1 needed when x is a factor
  geom_text(data = MIA_Year, aes(label=n), vjust = -0.9) +
  scale_y_continuous(limits = c(0, 100), breaks = seq(0, 100, by = 10)) +
  labs(x = "", y = "Percent of Articles") +
  theme(axis.text.x = element_text(angle = 45, hjust = 1), panel.border = element_rect(fill = NA), panel.background = element_rect(fill = "white"), panel.grid = element_line(colour = "grey85"))

This is my code. I tried including something like this vjust = ifelse(diff(Percent) < 0, -0.9, 0.9), but it did not work with ggplot, I got this error, although the object definitely is inside of MIA_YEAR: (Error in diff(y = Percent) : object 'Percent' not found) (maybe you could also explain to me, why it does not work?)

Thanks a lot for your help!

Edit 1. Here is the data (I hope I got the point with the copying right)

structure(list(YEAR = structure(1:13, .Label = c("1990", "2000", 
"2010", "2011", "2012", "2013", "2014", "2015", "2016", "2017", 
"2018", "2019", "2020"), class = "factor"), n = c(25L, 27L, 74L, 
95L, 79L, 79L, 98L, 98L, 102L, 79L, 101L, 86L, 99L), Percent = c(26.6, 
25.23, 36.63, 48.72, 44.63, 36.24, 43.75, 42.24, 44.54, 34.96, 
46.98, 35.98, 41.42)), class = c("grouped_df", "tbl_df", "tbl", 
"data.frame"), row.names = c(NA, -13L), groups = structure(list(
    YEAR = structure(1:13, .Label = c("1990", "2000", "2010", 
    "2011", "2012", "2013", "2014", "2015", "2016", "2017", "2018", 
    "2019", "2020"), class = "factor"), .rows = structure(list(
        1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 13L), ptype = integer(0), class = c("vctrs_list_of", 
    "vctrs_vctr", "list"))), class = c("tbl_df", "tbl", "data.frame"
), row.names = c(NA, -13L), .drop = TRUE))

IMHO you are on the right track. Try with moving `vjust` inside `aes()` when you want to do computations on columns or perhaps even better do this computation outside of ggplot(). For more help please provide [a minimal reproducible example](https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example) including a snippet of your data or some fake data best shared via `dput()`, e.g. run `dput(NAME_OF_DATASET)` and copy he output into your post. — stefan, Jun 15 '23 at 13:19
Thanks for your help stefan, I added the reproducible example in the post. In the meanwhile I will try if I can figure it out by myself. — blubdidub, Jun 15 '23 at 13:31
Please provide enough code so others can better understand or reproduce the problem. — Community, Jun 15 '23 at 13:37
One further remark. As `vjust` is basically the vertical alignment I would suggest to shift or nudge the labels via `y`, e.g. `y = Percent + ifelse(...)`. — stefan, Jun 15 '23 at 13:40

stefan · Accepted Answer · 2023-06-15T19:22:18.297

Building on your idea, here is a working approach where - as mentioned in my comment - I "nudge" the y position of the labels and use vjust for the alignment. Also note, that I have taken the lead first differences or slopes into account to place the labels.

library(ggplot2)
library(dplyr, warn = FALSE)

MIA_Year |>
  ungroup() |>
  arrange(YEAR) |>
  mutate(
    sign = c(0, diff(Percent)) < 0,
    lead_sign = lead(sign, default = FALSE),
    nudge_y = 3 * ifelse(sign & !lead_sign, -1, 1),
    vjust = ifelse(sign & !lead_sign, 1, 0)
  ) |>
  ggplot(aes(x = YEAR, y = Percent)) +
  geom_line(group = 1, color = "steelblue", linewidth = 1) +
  geom_text(aes(y = Percent + nudge_y, label = n, vjust = vjust)) +
  scale_y_continuous(limits = c(0, 100), breaks = seq(0, 100, by = 10)) +
  labs(x = "", y = "Percent of Articles") +
  theme(
    axis.text.x = element_text(angle = 45, hjust = 1),
    panel.border = element_rect(fill = NA),
    panel.background = element_rect(fill = "white"),
    panel.grid = element_line(colour = "grey85")
  )

ggplot line plot: is there a way to depict the data points under or over the line plot depending on what looks better?

1 Answers1