compare boxplots with a single value - r

I want to compare the distribution of several variables (here X1 and X2) with a single value (here bm). The issue is that these variables are too many (about a dozen) to use a single boxplot.
Additionaly the levels are too different to use one plot. I need to use facets to make things more organised:
However with this plot my benchmark category (bm), which is a single value in X1 and X2, does not appear in X1 and seems to have several values in X2. I want it to be only this green line, which it is in the first plot. Any ideas why it changes? Is there any good workaround? I tried the options of facet_wrap/facet_grid, but nothing there delivered the right result.
I also tried combining a bar plot with bm and three empty categories with the boxplot. But firstly it looked terrible and secondly it got similarly screwed up in the facetting. Basically any work around would help.
Below the code to create the minimal example displayed here:
# Creating some sample data & loading libraries
library(ggplot2)
library(RColorBrewer)
set.seed(10111)
x=matrix(rnorm(40),20,2)
y=rep(c(-1,1),c(10,10))
x[y==1,]=x[y==1,]+1
x[,2]=x[,2]+20
df=data.frame(x,y)
# creating a benchmark point
benchmark=data.frame(y=rep("bm",2),key=c("X1","X2"),value=c(-0.216936,20.526312))
# melting the data frame, rbinding it with the benchmark
test_dat=rbind(tidyr::gather(df,key,value,-y),benchmark)
# Creating a plot
p_box <- ggplot(data = test_dat, aes(x=key, y=value,color=as.factor(test_dat$y))) +
geom_boxplot() + scale_color_manual(name="Cluster",values=brewer.pal(8,"Set1"))
# The first line delivers the first plot, the second line the second plot
p_box
p_box + facet_wrap(~key,scales = "free",drop = FALSE) + theme(legend.position = "bottom")

The problem only lies int the use of test_dat$y inside the color aes. Never use $ in aes, ggplot will mess up.
Anyway, I think you plot would improve if you use a geom_hline for the benchmark, instead of hacking in a single value boxplot:
library(ggplot2)
library(RColorBrewer)
ggplot(tidyr::gather(df,key,value,-y)) +
geom_boxplot(aes(x=key, y=value, color=as.factor(y))) +
geom_hline(data = benchmark, aes(yintercept = value), color = '#4DAF4A', size = 1) +
scale_color_manual(name="Cluster",values=brewer.pal(8,"Set1")) +
facet_wrap(~key,scales = "free",drop = FALSE) +
theme(legend.position = "bottom")

Related

What is the purpose of using facet_grid(variable ~ .) instead of just using facet_wrap?

So I'm self-teaching myself R right now using this online resource: "https://r4ds.had.co.nz/data-visualisation.html#facets"
This particular section is going over the use of facet_wrap and facet_grid. It's clear to me that facet_grid is primarily used when wanting to visualize a plot along two additional dimensions, rather than just one. What I don't understand is why you can use facet_grid(.~variable) or facet_grid(variable~.) to basically achieve the same result as facet_wrap. Putting a "." in place of a variable results in just not faceting along the row or column dimension, or in other words showing 1 additional variable just as facet_wrap would do.
If anyone can shed some light on this, thank you!
If you use facet_grid, the facets will always be in one row/column. They will never wrap to make a rectangle. But really if you just have one variable with few levels, it doesn't much matter.
You can also see that facet_grid(.~variable) and facet_grid(variable~.) will put the facet labels in different places (row headings vs column headings)
mg <- ggplot(mtcars, aes(x = mpg, y = wt)) + geom_point()
mg + facet_grid(vs~ .) + labs(title="facet_grid(vs~ .)"),
mg + facet_grid(.~ vs) + labs(title="facet_grid(.~ vs)")
So in the most simple of cases, there's nothing that different between them. The main reason to use facet_grid is to have a single, common axis for all facets so you can easily scan across all panels to make a direct comparison of data.
Actually, the same result is not produced all the time...
The number of facets which appear across the graphs pane is fixed with facet_grid (always the number of unique values in the variable) where as facet_wrap, like its name suggests, wraps the facets around the graphics pane. In this way the functions only result in the same graph when the number of facets produced is small.
Both facet_grid and facet_wrap take their arguments in the form row~columns, and nowdays we don't need to use the dot with facet_grid.
In order to compare their differences let's add a new variable with 8 unqiue values to the mtcars data set:
library(tidyverse)
mtcars$example <- rep(1:8, length.out = 32)
ggplot()+
geom_point(data = mtcars, aes(x = mpg, y = wt))+
facet_grid(~example, labeller = label_both)
Which results in a cluttered plot:
Compared to:
ggplot()+
geom_point(data = mtcars, aes(x = mpg, y = wt))+
facet_wrap(~example, labeller = label_both)
Which results in:

increase distance between stack of geom_line()

I have some diffraction data from XRD. I'd like to plot it all in one chart but stacked. Because the range of y is quite large, stacking is not so straight forward. there's a link to data if you wish to play and the simple script is below
https://www.dropbox.com/s/b9kyubzncwxge9j/xrd.csv?dl=0
library(dplyr)
library(ggplot2)
#load it up
xrd <- read.csv("xrd.csv")
#melt it
xrd.m = melt(xrd, id.var="Degrees_2_Theta")
# Reorder so factor levels are grouped together
xrd.m$variable = factor(xrd.m$variable,
levels=sort(unique(as.character(xrd.m$variable))))
names(xrd.m)[names(xrd.m) == "variable"] <- "Sample"
names(xrd.m)[names(xrd.m) == "Degrees_2_Theta"] <- "angle"
#colours use for nearly everything
cbPalette <- c("#000000", "#E69F00", "#56B4E9", "#009E73", "#F0E442", "#0072B2", "#D55E00", "#CC79A7")
#plot
ggplot(xrd.m, aes(angle, value, colour=Sample, group=Sample)) +
geom_line(position = "stack") +
scale_colour_manual(values=cbPalette) +
theme_linedraw() +
theme(legend.position = "none",
axis.text.y=element_blank(),
axis.ticks.y=element_blank()) +
labs(x="Degrees 2-theta", y="Intensity - stacked for clarity")
Here is the plot- as you can see it's not quite stacked
Here is something I had in excel a way back. ugly - but slightly better
I'm not sure that I will actually use the stacked plot function from R because I find it always looks off from past experience and instead might use the same data manipulation I used from excel.
It seems that you have a different understanding of the result of applying position="stack" on your geom_line() than what actually is happening. What you're looking to do is probably best served by either using faceting or creating a ridgeline plot. I will give you solutions for both of those approaches here with some example data (sorry, I don't click dropbox links and they will eventually break anyway).
What does position="stack" actually do?
The result of position="stack" will be that your y values of each line will be added, or "stacked", together in the resulting plot. That means that the lines as drawn will only actually accurately reflect the actual value in the data for one of the lines, and the other will be "added on top" of that (stacked). The behavior is best illustrated via an example:
ex <- data.frame(x=c(1,1,2,2,3,3), y=c(1,5,1,2,1,1), grp=rep(c('A','B'),3))
ggplot(ex, aes(x,y, color=grp)) + geom_line()
The y values for "A" are equal to 1 at all values of x. This is the same as indicating position="identity". Now, let's see what happens if we use position="stack":
ggplot(ex, aes(x,y, color=grp)) + geom_line(position="stack")
You should see, the value of y plotted for "B" is equal to B, whereas the y value for "A" is actually the value for "A" added to the value for "B". Hope that makes sense.
Faceting
What you're trying to do is take the overlapping lines you have and "separate" them vertically, right? That's not quite stacking, as you likely want to maintain their y values as position="identity" (the default). One way to do that quite easily is to use faceting, which creates what you could call "stacked plots" according to one or two variables in your dataset. In this case, I'm using example data (for reasons outlined above), but you can use this to understand how you want to arrange your own data.
set.seed(1919191)
df <- data.frame(
x=rep(1:100, 5),
y=c(rnorm(100,0,0.1), rnorm(100,0,0.2), rnorm(100,0,0.3), rnorm(100,0,0.4), rnorm(100,0,0.5)),
sample_name=c(rep('A',100), rep('B',100), rep('C',100), rep('D',100), rep('E',100)))
# plot code
p <- ggplot(df, aes(x,y, color=sample_name))
p + geom_line() + facet_grid(sample_name ~ .)
Create a Ridgeline Plot
The other way that kind of does the same thing is to create what is known as a ridgeline plot. You can do this via the package ggridges and here's an example using geom_ridgeline():
p + geom_ridgeline(
aes(y=sample_name, height=y),
fill=NA, scale=1, min_height=-Inf)
The idea here is to understand that geom_ridgeline() changes your y axis to be the grouping variable (so we actually have to redefine that in aes()), and the actual y value for each of those groups should be assigned to the height= aesthetic. If you have data that has negative y values (now height= values), you'll also want to set the min_height=, or it will cut them off at 0 by default. You can also change how much each of the groups are separated by playing with scale= (does not always change in the way you think it would, btw).

How does one control the appearance (e.g. line size, line type, colour) of mqgam plots produced using plot.mgamViz from the "mgcViz" package?

I am using quantile regression in R with the qgam package and visualising them using the mgcViz package, but I am struggling to understand how to control the appearance of the plots. The package effectively turns gams (in my case mqgams) into ggplots.
Simple reprex:
egfit <- mqgam(data = iris,
Sepal.Length ~ s(Petal.Length),
qu = c(0.25,0.5,0.75))
plot.mgamViz(getViz(egfit))
I am able to control things that can be added, for example the axis labels and theme of the plot, but I'm struggling to effect things that would normally be addressed in the aes() or geom_x() functions.
How would I control the thickness of the line? If this were a normal geom_smooth() or geom_line() I'd simply put size = 1 inside of the geoms, but I cannot see how I'd do so here.
How can I control the linetype of these lines? The "id" is continuous and one cannot supply a linetype to a continuous scale. If this were a nomral plot I would convert "id" to a character, but I can't see a way of doing so with the plot.mgamViz function.
How can I supply a new colour scale? It seems as though if I provide it with a new colour scale it invents new ID values to put on the legend that don't correlate to the actual "id" values, e.g.
plot.mgamViz(getViz(egfit)) + scale_colour_viridis_c()
I fully expect this to be relatively simple and I'm missing something obvious, and imagine the answer to all three of these subquestions are very similar to one another. Thanks in advance.
You need to extract your ggplot element using this:
p1 <- plot.mgamViz(getViz(egfit))
p <- p1$plots [[1]]$ggObj
Then, id should be as.factor:
p$data$id <- as.factor(p$data$id)
Now you can play with ggplot elements as you prefer:
library(mgcViz)
egfit <- mqgam(data = iris,
Sepal.Length ~ s(Petal.Length),
qu = c(0.25,0.5,0.75))
p1 <- plot.mgamViz(getViz(egfit))
# Taking gg infos and convert id to factor
p <- p1$plots [[1]]$ggObj
p$data$id <- as.factor(p$data$id)
# Changing ggplot attributes
p <- p +
geom_line(linetype = 3, size = 1)+
scale_color_brewer(palette = "Set1")+
labs(x="Petal Length", y="s(Petal Length)", color = "My ID labels:")+
theme_classic(14)+
theme(legend.position = "bottom")
p
Here the generated plot:
Hope it is useful!

ggplot boxplots with scatterplot overlay (same variables)

I'm an undergrad researcher and I've been teaching myself R over the past few months. I just started trying ggplot, and have run into some trouble. I've made a series of boxplots looking at the depth of fish at different acoustic receiver stations. I'd like to add a scatterplot that shows the depths of the receiver stations. This is what I have so far:
data <- read.csv(".....MPS.csv", header=TRUE)
df <- data.frame(f1=factor(data$Tagging.location), #$
f2=factor(data$Station),data$Detection.depth)
df2 <- data.frame(f2=factor(data$Station), data$depth)
df$f1f2 <- interaction(df$f1, df$f2) #$
plot1 <- ggplot(aes(y = data$Detection.depth, x = f2, fill = f1), data = df) + #$
geom_boxplot() + stat_summary(fun.data = give.n, geom = "text",
position = position_dodge(height = 0, width = 0.75), size = 3)
plot1+xlab("MPS Station") + ylab("Depth(m)") +
theme(legend.title=element_blank()) + scale_y_reverse() +
coord_cartesian(ylim=c(150, -10))
plot2 <- ggplot(aes(y=data$depth, x=f2), data=df2) + geom_point()
plot2+scale_y_reverse() + coord_cartesian(ylim=c(150,-10)) +
xlab("MPS Station") + ylab("Depth (m)")
Unfortunately, since I'm a new user in this forum, I'm not allowed to upload images of these two plots. My x-axis is "Stations" (which has 12 options) and my y-axis is "Depth" (0-150 m). The boxplots are colour-coded by tagging site (which has 2 options). The depths are coming from two different columns in my spreadsheet, and they cannot be combined into one.
My goal is to to combine those two plots, by adding "plot2" (Station depth scatterplot) to "plot1" boxplots (Detection depths). They are both looking at the same variables (depth and station), and must be the same y-axis scale.
I think I could figure out a messy workaround if I were using the R base program, but I would like to learn ggplot properly, if possible. Any help is greatly appreciated!
Update: I was confused by the language used in the original post, and wrote a slightly more complicated answer than necessary. Here is the cleaned up version.
Step 1: Setting up. Here, we make sure the depth values in both data frames have the same variable name (for readability).
df <- data.frame(f1=factor(data$Tagging.location), f2=factor(data$Station), depth=data$Detection.depth)
df2 <- data.frame(f2=factor(data$Station), depth=data$depth)
Step 2: Now you can plot this with the 'ggplot' function and split the data by using the `col=f1`` argument. We'll plot the detection data separately, since that requires a boxplot, and then we'll plot the depths of the stations with colored points (assuming each station only has one depth). We specify the two different plots by referencing the data from within the 'geom' functions, instead of specifying the data inside the main 'ggplot' function. It should look something like this:
ggplot()+geom_boxplot(data=df, aes(x=f2, y=depth, col=f1)) + geom_point(data=df2, aes(x=f2, y=depth), colour="blue") + scale_y_reverse()
In this plot example, we use boxplots to represent the detection data and color those boxplots by the site label. The stations, however, we plot separately using a specific color of points, so we will be able to see them clearly in relation to the boxplots.
You should be able to adjust the plot from here to suit your needs.
I've created some dummy data and loaded into the chart to show you what it would look like. Keep in mind that this is purely random data and doesn't really make sense.

Is it possible to create 3 series (2 lines and one point) faceted plot in ggplot?

I am trying to write a code that I wrote with a basic graphics package in R to ggplot.
The graph I obtained using the basic graphics package is as follows:
I was wondering whether this type of graph is possible to create in ggplot2. I think we could create this kind of graph by using panels but I was wondering is it possible to use faceting for this kind of plot. The major difficulty I encountered is that maximum and minimum have common lengths whereas the observed data is not continuous data and the interval is quite different.
Any thoughts on arranging the data for this type of plot would be very helpful. Thank you so much.
Jdbaba,
From your comments, you mentioned that you'd like for the geom_point to have just the . in the legend. This is a feature that is yet to be implemented to be used directly in ggplot2 (if I am right). However, there's a fix/work-around that is given by #Aniko in this post. Its a bit tricky but brilliant! And it works great. Here's a version that I tried out. Hope it is what you expected.
# bind both your data.frames
df <- rbind(tempcal, tempobs)
p <- ggplot(data = df, aes(x = time, y = data, colour = group1,
linetype = group1, shape = group1))
p <- p + geom_line() + geom_point()
p <- p + scale_shape_manual("", values=c(NA, NA, 19))
p <- p + scale_linetype_manual("", values=c(1,1,0))
p <- p + scale_colour_manual("", values=c("#F0E442", "#0072B2", "#D55E00"))
p <- p + facet_wrap(~ id, ncol = 1)
p
The idea is to first create a plot with all necessary attributes set in the aesthetics section, plot what you want and then change settings manually later using scale_._manual. You can unset lines by a 0 in scale_linetype_manual for example. Similarly you can unset points for lines using NA in scale_shape_manual. Here, the first two values are for group1=maximum and minimum and the last is for observed. So, we set NA to the first two for maximum and minimum and set 0 to linetype for observed.
And this is the plot:
Solution found:
Thanks to Arun and Andrie
Just in case somebody needs the solution of this sort of problem.
The code I used was as follows:
library(ggplot2)
tempcal <- read.csv("temp data ggplot.csv",header=T, sep=",")
tempobs <- read.csv("temp data observed ggplot.csv",header=T, sep=",")
p <- ggplot(tempcal,aes(x=time,y=data))+geom_line(aes(x=time,y=data,color=group1))+geom_point(data=tempobs,aes(x=time,y=data,colour=group1))+facet_wrap(~id)
p
The dataset used were https://www.dropbox.com/s/95sdo0n3gvk71o7/temp%20data%20observed%20ggplot.csv
https://www.dropbox.com/s/4opftofvvsueh5c/temp%20data%20ggplot.csv
The plot obtained was as follows:
Jdbaba

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