specifying number of breaks with scales in ggplot2 without a transform? - r

If I want my data axis to have more breaks but without a transformation on the values, how can I do it in ggplot2? eg:
... + scale_x_continuous(breaks=scales.trans_breaks("log2", function(x) 2^x, n=8), limits=limits)
works if you want your data transformed and the n= parameter lets you say how many breaks. How can you specify breaks without transforming the data? Do you just give it an identity function?

I prefer not to give explicit ticks based on calculations in the data, and so I want ggplot2 to pick the tick marks for me given only the limits and the number of ticks. This code works for me:
library(scales)
scale_x_continuous(breaks = trans_breaks(identity, identity, n = numticks))
of course you can always set the tick marks explicitly with breaks = ... as agstudy wrote.

you can give scale_x_continuous a vector of breaks like this :
n=5
breaks = seq(min(dat$x),max(dat$x), length.out = n)
m + scale_x_continuous(breaks=breaks)

Related

How can I mathematically transform the default labels on legend in ggplot?

I have a 2D surface plot made with ggplot which I am colouring to show the value of it's third dimension. This data is wide-ranging in the Z direction, so I have log-transformed it before doing the interpolation for plotting.
I like the default choices that the plotting algorithm has chosen for the breaks. However, the labels for those breaks are now the log values.
The current code for the colouring is:
scale_fill_viridis(breaks = waiver(), labels = waiver())
waiver() is a flag to the underlying algorithm to use default values. Ideally, I'd like to do something like
scale_fill_viridis(breaks = waiver(), labels = sprintf("%.1f", 10^waiver()))
but that breaks with a Error in 10^my_breaks : non-numeric argument to binary operator error
How can I mathematically transform the default values for the labels into the values they would be prior to the log transform?
How about something like this:
your_function <- function(x){sprintf("%.1f", 10^as.numeric(x))}
labels = scales::trans_format("identity", your_function)
your_function will take the inverse of log10, effectively undoing the log transform. scales::trans_format will reformat the given label by applying whatever function it passed to it, in this case your_function.
You can of course define the reformatting function inside trans_format but in order to make things as clear as possible I've done it in two steps.

Is it possible to over-ride the x axis range in R package ggbio when using autoplot and ensdb transcripts?

I am trying to use ggbio to plot gene transcripts. I want to plot a very specific range so it matches my ggplot2 plots. The problem is my example plot ends up having range of 133,567,500-133,570,000 regardless of the GRange and whether I specify xlim or not.
This example should only plot a small bit of intron (the thin arrowed line) but instead plots the full 2 exons and intron in between. I believe autoplot wants to plot the entire transcript or transcripts present in the range and widens the range to accommodate for that.
library(EnsDb.Hsapiens.v86)
library(ggbio)
ensdb <- EnsDb.Hsapiens.v86
mut<-GRanges("10", IRanges(133568909, 133569095))
gene <- autoplot(ensdb, which=mut, names.expr="gene_name",xlim=c(133568909,133569095))
gene.gg <- gene#ggplot
png("test_gene_plot_5.png")
gene.gg
dev.off()
Is there any way to over-ride this? I've looked at the manual page for autoplot and I couldn't narrow down an option that would fix it. Others have said to use xlim, but that does not seem to change anything
I like ggbio because it can make a ggplot2 object to be plotted along with other ggplot2 objects. I have not seen an example for that with other approaches like Gvis. But I would entertain other approaches if they could be combined with my existing plots.
Thanks!
Amy
It kind of depends wether you want clipped or squished data. Usually autoplot outputs a ggplot object at some point that can be manipulated as such.
For squished data:
library(GenomicRanges) # just to be sure start and end work
gene#ggplot +
scale_x_continuous(limits = c(start(mut), end(mut)), oob = scales::squish)
For clipped data:
gene#ggplot +
coord_cartesian(xlim = c(start(mut), end(mut)))
But to be totally honest, I'm unsure wether this is the most informative way to communicate that you are plotting the internals of an intron.
Alternatively, I've written a gene model geom at some point that doesn't work through the autoplot methods (which can sometimes be a pain if you want to customise everything). Downside is that you'd have to do some manual gene searching and setting aesthetics. Upside is that it works like most other geoms and is therefore easy to combine with some other data.
library(ggnomics) # from: https://github.com/teunbrand/ggnomics
# Finding a gene's exons manually
my_gene <- transcriptsByOverlaps(EnsDb.Hsapiens.v86, mut)
my_gene <- exonsByOverlaps(EnsDb.Hsapiens.v86, my_gene)
my_gene <- as.data.frame(my_gene)
some_other_data <- data.frame(
x = seq(start(mut), end(mut), by = 10),
y = cumsum(rnorm(19))
)
ggplot(some_other_data) +
geom_line(aes(x, y)) +
geom_genemodel(data = my_gene,
aes(xmin = start, xmax = end,
y = max(some_other_data$y) + 1,
group = 1, strand = strand)) +
coord_cartesian(xlim = c(start(mut), end(mut)))
Hope that helped!

Axis breaks in ggplot histogram in R [duplicate]

I have data that is mostly centered in a small range (1-10) but there is a significant number of points (say, 10%) which are in (10-1000). I would like to plot a histogram for this data that will focus on (1-10) but will also show the (10-1000) data. Something like a log-scale for th histogram.
Yes, i know this means not all bins are of equal size
A simple hist(x) gives
while hist(x,breaks=c(0,1,1.1,1.2,1.3,1.4,1.5,1.6,1.7,1.8,1.9,2,3,4,5,7.5,10,15,20,50,100,200,500,1000,10000))) gives
none of which is what I want.
update
following the answers here I now produce something that is almost exactly what I want (I went with a continuous plot instead of bar-histogram):
breaks <- c(0,1,1.1,1.2,1.3,1.4,1.5,1.6,1.7,1.8,1.9,2,4,8)
ggplot(t,aes(x)) + geom_histogram(colour="darkblue", size=1, fill="blue") + scale_x_log10('true size/predicted size', breaks = breaks, labels = breaks)![alt text][3]
the only problem is that I'd like to match between the scale and the actual bars plotted. There two options for doing that : the one is simply use the actual margins of the plotted bars (how?) then get "ugly" x-axis labels like 1.1754,1.2985 etc. The other, which I prefer, is to control the actual bins margins used so they will match the breaks.
Log scale histograms are easier with ggplot than with base graphics. Try something like
library(ggplot2)
dfr <- data.frame(x = rlnorm(100, sdlog = 3))
ggplot(dfr, aes(x)) + geom_histogram() + scale_x_log10()
If you are desperate for base graphics, you need to plot a log-scale histogram without axes, then manually add the axes afterwards.
h <- hist(log10(dfr$x), axes = FALSE)
Axis(side = 2)
Axis(at = h$breaks, labels = 10^h$breaks, side = 1)
For completeness, the lattice solution would be
library(lattice)
histogram(~x, dfr, scales = list(x = list(log = TRUE)))
AN EXPLANATION OF WHY LOG VALUES ARE NEEDED IN THE BASE CASE:
If you plot the data with no log-transformation, then most of the data are clumped into bars at the left.
hist(dfr$x)
The hist function ignores the log argument (because it interferes with the calculation of breaks), so this doesn't work.
hist(dfr$x, log = "y")
Neither does this.
par(xlog = TRUE)
hist(dfr$x)
That means that we need to log transform the data before we draw the plot.
hist(log10(dfr$x))
Unfortunately, this messes up the axes, which brings us to workaround above.
Using ggplot2 seems like the most easy option. If you want more control over your axes and your breaks, you can do something like the following :
EDIT : new code provided
x <- c(rexp(1000,0.5)+0.5,rexp(100,0.5)*100)
breaks<- c(0,0.1,0.2,0.5,1,2,5,10,20,50,100,200,500,1000,10000)
major <- c(0.1,1,10,100,1000,10000)
H <- hist(log10(x),plot=F)
plot(H$mids,H$counts,type="n",
xaxt="n",
xlab="X",ylab="Counts",
main="Histogram of X",
bg="lightgrey"
)
abline(v=log10(breaks),col="lightgrey",lty=2)
abline(v=log10(major),col="lightgrey")
abline(h=pretty(H$counts),col="lightgrey")
plot(H,add=T,freq=T,col="blue")
#Position of ticks
at <- log10(breaks)
#Creation X axis
axis(1,at=at,labels=10^at)
This is as close as I can get to the ggplot2. Putting the background grey is not that straightforward, but doable if you define a rectangle with the size of your plot screen and put the background as grey.
Check all the functions I used, and also ?par. It will allow you to build your own graphs. Hope this helps.
A dynamic graph would also help in this plot. Use the manipulate package from Rstudio to do a dynamic ranged histogram:
library(manipulate)
data_dist <- table(data)
manipulate(barplot(data_dist[x:y]), x = slider(1,length(data_dist)), y = slider(10, length(data_dist)))
Then you will be able to use sliders to see the particular distribution in a dynamically selected range like this:

Set categorical axis labels with scales "free" ggplot2

I am trying to set the labels on a categorical axis within a faceted plot using the ggplot2 package (1.0.1) in R (3.1.1) with scales="free". If I plot without manually setting the axis tick labels they appear correctly (first plot), but when I try to set the labels (second plot) only the first n labels are used on both facets (not in sequence as with the original labels).
Here is a reproducible code snippet exemplifying the problem:
foo <- data.frame(yVal=factor(letters[1:8]), xVal=factor(rep(1:4,2)), fillVal=rnorm(8), facetVar=rep(1:2,each=4))
## axis labels are correct
p <- ggplot(foo) + geom_tile(aes(x=xVal, y=yVal, fill=fillVal)) + facet_grid(facetVar ~ ., scales='free')
print(p)
## axis labels are not set correctly
p <- p + scale_y_discrete(labels=c('a','a','b','b','c','d','d','d'))
print(p)
I note that I cannot set the labels correctly within the data.frame as they are not unique. Also I am aware that I can accomplish this with arrange.grid, but this requires "manually" aligning the plots if there are different length labels etc. Additionally, I would like to have the facet labels included in the plot which is not an available option with the arrange.grid solution. Also I haven't tried viewports yet. Maybe that is the solution, but I was hoping for more of the faceted look to this plot and that seems to be more similar to grid.arrange.
It seems to me as though this is a bug, but I am open to an explanation as to how this might be a "feature". I also hope that there might be a simple solution to this problem that I have not thought of yet!
The easiest method would be to create another column in your data set with the right conversion. This would also be easier to audit and manipulate. If you insist on changing manually:
You cannot simply set the labels directly, as it recycles (I think) the label vector for each facet. Instead, you need to set up a conversion using corresponding breaks and labels:
p <- p + scale_y_discrete(labels = c('1','2','3','4','5','6','7','8'), breaks=c('a','b','c','d','e','f','g','h'))
print(p)
Any y axis value of a will now be replaced with 1, b with 2 and so on. You can play around with the label values to see what I mean. Just make sure that every factor value you have is also represented in the breaks argument.
I think I may actually have a solution to this. My problem was that my labels were not correct because as someone above has said - it seems like the label vector is recycled through. This line of code gave me incorrect labels.
ggplot(dat, aes(x, y))+geom_col()+facet_grid(d ~ t, switch = "y", scales = "free_x")+ylab(NULL)+ylim(0,10)+geom_text(aes(label = x))
However when the geom_text was moved prior to the facet_grid, the below code gave me correct labels.
ggplot(dat, aes(x, y))+geom_col()+geom_text(aes(label = x))+facet_grid(d ~ t, switch = "y", scales = "free_x")+ylab(NULL)+ylim(0,10)
There's a good chance I may have misunderstood the problem above, but I certainly solved my problem so hopefully this is helpful to someone!

How can I plot a histogram of a long-tailed data using R?

I have data that is mostly centered in a small range (1-10) but there is a significant number of points (say, 10%) which are in (10-1000). I would like to plot a histogram for this data that will focus on (1-10) but will also show the (10-1000) data. Something like a log-scale for th histogram.
Yes, i know this means not all bins are of equal size
A simple hist(x) gives
while hist(x,breaks=c(0,1,1.1,1.2,1.3,1.4,1.5,1.6,1.7,1.8,1.9,2,3,4,5,7.5,10,15,20,50,100,200,500,1000,10000))) gives
none of which is what I want.
update
following the answers here I now produce something that is almost exactly what I want (I went with a continuous plot instead of bar-histogram):
breaks <- c(0,1,1.1,1.2,1.3,1.4,1.5,1.6,1.7,1.8,1.9,2,4,8)
ggplot(t,aes(x)) + geom_histogram(colour="darkblue", size=1, fill="blue") + scale_x_log10('true size/predicted size', breaks = breaks, labels = breaks)![alt text][3]
the only problem is that I'd like to match between the scale and the actual bars plotted. There two options for doing that : the one is simply use the actual margins of the plotted bars (how?) then get "ugly" x-axis labels like 1.1754,1.2985 etc. The other, which I prefer, is to control the actual bins margins used so they will match the breaks.
Log scale histograms are easier with ggplot than with base graphics. Try something like
library(ggplot2)
dfr <- data.frame(x = rlnorm(100, sdlog = 3))
ggplot(dfr, aes(x)) + geom_histogram() + scale_x_log10()
If you are desperate for base graphics, you need to plot a log-scale histogram without axes, then manually add the axes afterwards.
h <- hist(log10(dfr$x), axes = FALSE)
Axis(side = 2)
Axis(at = h$breaks, labels = 10^h$breaks, side = 1)
For completeness, the lattice solution would be
library(lattice)
histogram(~x, dfr, scales = list(x = list(log = TRUE)))
AN EXPLANATION OF WHY LOG VALUES ARE NEEDED IN THE BASE CASE:
If you plot the data with no log-transformation, then most of the data are clumped into bars at the left.
hist(dfr$x)
The hist function ignores the log argument (because it interferes with the calculation of breaks), so this doesn't work.
hist(dfr$x, log = "y")
Neither does this.
par(xlog = TRUE)
hist(dfr$x)
That means that we need to log transform the data before we draw the plot.
hist(log10(dfr$x))
Unfortunately, this messes up the axes, which brings us to workaround above.
Using ggplot2 seems like the most easy option. If you want more control over your axes and your breaks, you can do something like the following :
EDIT : new code provided
x <- c(rexp(1000,0.5)+0.5,rexp(100,0.5)*100)
breaks<- c(0,0.1,0.2,0.5,1,2,5,10,20,50,100,200,500,1000,10000)
major <- c(0.1,1,10,100,1000,10000)
H <- hist(log10(x),plot=F)
plot(H$mids,H$counts,type="n",
xaxt="n",
xlab="X",ylab="Counts",
main="Histogram of X",
bg="lightgrey"
)
abline(v=log10(breaks),col="lightgrey",lty=2)
abline(v=log10(major),col="lightgrey")
abline(h=pretty(H$counts),col="lightgrey")
plot(H,add=T,freq=T,col="blue")
#Position of ticks
at <- log10(breaks)
#Creation X axis
axis(1,at=at,labels=10^at)
This is as close as I can get to the ggplot2. Putting the background grey is not that straightforward, but doable if you define a rectangle with the size of your plot screen and put the background as grey.
Check all the functions I used, and also ?par. It will allow you to build your own graphs. Hope this helps.
A dynamic graph would also help in this plot. Use the manipulate package from Rstudio to do a dynamic ranged histogram:
library(manipulate)
data_dist <- table(data)
manipulate(barplot(data_dist[x:y]), x = slider(1,length(data_dist)), y = slider(10, length(data_dist)))
Then you will be able to use sliders to see the particular distribution in a dynamically selected range like this:

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