使用 ggplot2 仅将一个轴转换为 log10 比例
I have the following problem: I would like to visualize a discrete and a continuous variable on a boxplot in which the latter has a few extreme high values. This makes the boxplot meaningless (the points and even the "body" of the chart is too small), that is why I would like to show this on a log10 scale. I am aware that I could leave out the extreme values from the visualization, but I am not intended to.
Let's see a simple example with diamonds data:
m <- ggplot(diamonds, aes(y = price, x = color))
https://i.stack.imgur.com/aK2Ro.png
The problem is not serious here, but I hope you could imagine why I would like to see the values at a log10 scale. Let's try it:
m + geom_boxplot() + coord_trans(y = "log10")
https://i.stack.imgur.com/ifWhk.png
As you can see the y axis is log10 scaled and looks fine but there is a problem with the x axis, which makes the plot very strange.
The problem do not occur with scale_log, but this is not an option for me, as I cannot use a custom formatter this way. E.g.:
m + geom_boxplot() + scale_y_log10()
https://i.stack.imgur.com/SUdX5.png
My question: does anyone know a solution to plot the boxplot with log10 scale on y axis which labels could be freely formatted with a formatter function like in this thread?
Editing the question to help answerers based on answers and comments:
What I am really after: one log10 transformed axis (y) with not scientific labels. I would like to label it like dollar (formatter=dollar) or any custom format.
If I try @hadley's suggestion I get the following warnings:
> m + geom_boxplot() + scale_y_log10(formatter=dollar)
Warning messages:
1: In max(x) : no non-missing arguments to max; returning -Inf
2: In max(x) : no non-missing arguments to max; returning -Inf
3: In max(x) : no non-missing arguments to max; returning -Inf
With an unchanged y axis labels:
https://i.stack.imgur.com/sRScn.png
coord_trans - but you can specify custom labels to scale_y_log10...
+ scale_y_continous(formatter=dollar) just do not work. I cannot see the result of any formatter given and I also get three In max(x) : no non-missing arguments to max; returning -Inf warnings messages.
formatter="dollar"?
The simplest is to just give the 'trans' (formerly 'formatter') argument of either the scale_x_continuous or the scale_y_continuous the name of the desired log function:
library(ggplot2) # which formerly required pkg:plyr
m + geom_boxplot() + scale_y_continuous(trans='log10')
EDIT: Or if you don't like that, then either of these appears to give different but useful results:
m <- ggplot(diamonds, aes(y = price, x = color), log="y")
m + geom_boxplot()
m <- ggplot(diamonds, aes(y = price, x = color), log10="y")
m + geom_boxplot()
EDIT2 & 3: Further experiments (after discarding the one that attempted successfully to put "$" signs in front of logged values):
# Need a function that accepts an x argument
# wrap desired formatting around numeric result
fmtExpLg10 <- function(x) paste(plyr::round_any(10^x/1000, 0.01) , "K $", sep="")
ggplot(diamonds, aes(color, log10(price))) +
geom_boxplot() +
scale_y_continuous("Price, log10-scaling", trans = fmtExpLg10)
https://i.stack.imgur.com/vRKpS.png
Note added mid 2017 in comment about package syntax change:
scale_y_continuous(formatter = 'log10') is now scale_y_continuous(trans = 'log10') (ggplot2 v2.2.1)
I had a similar problem and this scale worked for me like a charm:
breaks = 10**(1:10)
scale_y_log10(breaks = breaks, labels = comma(breaks))
as you want the intermediate levels, too (10^3.5), you need to tweak the formatting:
breaks = 10**(1:10 * 0.5)
m <- ggplot(diamonds, aes(y = price, x = color)) + geom_boxplot()
m + scale_y_log10(breaks = breaks, labels = comma(breaks, digits = 1))
After executing::
https://i.stack.imgur.com/jAFcn.png
dollar formatter or by writing a custom one: + scale_y_log10(breaks = breaks, labels = dollar(breaks))
Another solution using scale_y_log10 with trans_breaks, trans_format and annotation_logticks()
library(ggplot2)
m <- ggplot(diamonds, aes(y = price, x = color))
m + geom_boxplot() +
scale_y_log10(
breaks = scales::trans_breaks("log10", function(x) 10^x),
labels = scales::trans_format("log10", scales::math_format(10^.x))
) +
theme_bw() +
annotation_logticks(sides = 'lr') +
theme(panel.grid.minor = element_blank())
https://i.imgur.com/nNvsOPv.png
I think I got it at last by doing some manual transformations with the data before visualization:
d <- diamonds
# computing logarithm of prices
d$price <- log10(d$price)
And work out a formatter to later compute 'back' the logarithmic data:
formatBack <- function(x) 10^x
# or with special formatter (here: "dollar")
formatBack <- function(x) paste(round(10^x, 2), "$", sep=' ')
And draw the plot with given formatter:
m <- ggplot(d, aes(y = price, x = color))
m + geom_boxplot() + scale_y_continuous(formatter='formatBack')
https://i.stack.imgur.com/L8HF6.png
Sorry to the community to bother you with a question I could have solved before! The funny part is: I was working hard to make this plot work a month ago but did not succeed. After asking here, I got it.
Anyway, thanks to @DWin for motivation!
fmtLg10dlr <- function(x) dollar(log10(x)); m + geom_boxplot() + scale_y_continuous(formatter='fmtLg10dlr'), but it just looks "wrong" to me.ggplot(diamonds, aes(color, log10(price))) + geom_boxplot() + scale_y_continuous(formatter = function(x) format(10 ^ x))- you need to transform the data and back-transform the labels.scale_y_continuous(formatter = 'log10')is nowscale_y_continuous(trans = 'log10')(ggplot2 v2.2.1)