Custom tick marks and borders in guide_colorbar

[jeffreyhanson]

Custom tick marks and borders in guide_colorbar

This pull request allows the user to manually change the appearance of tick marks and borders around colorbar legends. Following a discussion on stackoverflow, a feature request was raised, but there was not enough resources to implement it at the time.

The original problem is shown below. The use of white in a color ramp results in a legend which seems to disappear at the end. Additionally, the ticks marks are hard to see.

#  Data
require(ggplot2)
require(grid)
n <- 100
x <- y <- seq(-4*pi, 4*pi, len=n)
r <- cos(sqrt(outer(x^2, y^2, "+"))^2)
df <- data.frame(x = rep(x , each = n), y = rep(y, times = n ), val = c(r))

# Plot
ggplot(df, aes( x, y, fill = val)) +
  geom_raster() +
  scale_fill_gradient(low = "#FFFFFF", high = "#de2d26") +
  theme_bw() +
  theme(line = element_line(colour = "#0000FF")) +
  guides(fill = guide_colourbar(barheight = unit(3, "in")))

The pull request updates that allow the user to specify element_line objects that dictate the appearance of the legend. By using features in the pull request, we can specify black tick marks and borders to fix this issue.

# Plot with better legend
ggplot(df, aes( x, y, fill = val)) +
  geom_raster() +
  scale_fill_gradient(low = "#FFFFFF", high = "#de2d26") +
  theme_bw() +
  theme(line = element_line(colour = "#0000FF")) +
  guides(fill = guide_colourbar(barheight = unit(3, "in"),
   ticks=element_line(color='black'), border=element_line(color='black')))

This is my first "real" pull request on Github, so please let me know if I'm doing anything wrong :)

---

EDIT: fix typo

[hadley]

Can you please remove these minor changes that aren't related to your new functionality? That makes it easier for me to review.

[hadley]

Bump

[hadley]

Extra '

[jeffreyhanson]

I've made the changes - let me know if there's anything else I can do.

[hadley]

You're currently specifying the default in two places - here and above in the parameter list. I think it would be better to specify only in one place.

I'd recommend restructuring this if block to cover all cases:

if (identical(ticks, TRUE)) { 

} else if (identical(ticks, FALSE)) {

} else if (inherits(ticks, "element")) {

} else {
  stop("`ticks` should be ...", call. = FALSE)
}

[hadley]

Actually, thinking about it more, shouldn't the default come from the theme system?

[hadley]

Closing due to apparent lack of interest

[DanOvando]

I'd like to add my vote for this feature if interest arises again, I've been trying to do this for quite a long time. Let me know if I can be of help getting this in place

[PeteCowman]

I would like to see this feature also!

[ko-ichi-h]

Me too. I really hope we can use this feature!

[komodovaran]

Would love to have it re-opened. ggplot's colorbar is doesn't seem quite right compared to colorbars from Matlab or Python.

[jdeut]

I also opt for this feature! White on white sucks..

[srgorelik]

I would really like this feature as well. It would be very useful to be able to change the color of the colorbar border and tick marks.

[johnbaums]

+1 - This is the one thing that stops me from using ggplot for spatial viz.

[josetanago]

+1, same problem, white ticks in colorbars with light colors are not visible!

[batpigandme]

HI @DanOvando @josetanago @johnbaums @srgorelik @nichtleiter @komodovaran @ko-ichi-h @PeteCowman ,

The best way to add your +1 is by adding it (the +1 reaction, 👍) to the original issue. It's easiest for us to keep track of!

Thanks

[clauswilke]

This effect can now be achieved, using a slightly different syntax: #2541
I only found this abandoned pull request now, that mine has been merged. Arguably, the API of this one was a bit cleaner.

[johnbaums]

Hallelujah! This was a long time coming. Thanks to all that drove this.

[jeffreyhanson]

Awesome! Thank you so much for implementing this functionality @clauswilke!

[lock]

This old issue has been automatically locked. If you believe you have found a related problem, please file a new issue (with reprex) and link to this issue. https://reprex.tidyverse.org/