Data Background: I have a large data frame (50,000 values, 10,000 when removing NAs) for a single chromosome. I am trying to plot a fixation index (Y-range: 0-1)(data$'N:S') across chromosomal positions (X-range: 0-250,000,000)(data$'pos'). I used a program (popoolation 2) to calculate sliding window averages for a window size of 50,000 and a step size of 10,000, resulting in my data. However, on R this is too noisy and it comes out looking like a blob. When I zoom in by changing the x-axis so each tick is 500,000 separation, you can see the trends nicely. I think I can fix this on a large chromosomal stage by increasing the area of the x-axis and finding a way to simplify the data.
Currently I have: All my data plotted, simple mean, StandDevs (color coded)
I am trying to figure out two things.
1 Is there a way to extend the X-axis to stretch out the length of it. I don't want to change the markers on it or what it displays, I want to make the actual length longer. (Example, if I had a graph on a piece of paper that showed an x-Axis of 1-10 on a 2" area, I would want to increase the area to 5", not change the defined limits to say 1-100. so, not xlim function)
2 Simplify the data in some way. I was thinking easiest would be a smoothed or rolling mean across the data. When I use rollmean() or smooth() it separates my data from the x-axis, so it only extends to the 8,000 points and when I plot it doesn't go across the whole chromosomal graph with the rest of my data. Someone mentioned there may be away to instead randomly sample data to simplify it?
2B If I get a trendline to work, can I color code it so that part of it that is 1 or 2 standard deviations above the mean can be a different color if I mute my actual background data and remove its color.
R Code
Image 1-Plotting All Positions
plot(data$'Pos',data$'N:S', ylim=c(0,0.5), col=data$Colour)
Image 3-I tried both
lines(smooth(datatest$`N:S`), type="l", col = "blue", lwd = 1)
and
rolling = rollmean(datatest$N:S, 9)
lines(rolling, type="b", col = "purple", lwd = 1)
Image 2-Plotting a Nice Subsection-- why I want to extend X-axis
plot(data$'Pos',data$'N:S', ylim=c(0,0.5), xlim=c(163000000,165000000), col=data$Colour)
Notes:
If it matters, my graph has colored points due to color coded regions related to means and Standard Dev.
data$Colour[data$'N:S'>=data_SD1above]="orange"
Also, the only difference between data and datatest was that datatest had NA values removed.
Image 1: All Positions-Messy
Image 2: Zoomed In to see trends
Image 3: All positions with the two attempted trendlines
So it seems like that you want to resize the width of the graph for the visualization.
if you use Rstudio, there is an output option which changes the width and height of the graph.
if you use the console, you can save your plot with width and height. for example
png("mychromosome.png".width=1000,height=300)
plot(..blah..blah..)
dev.off()
I hope it will help you.
Related
I have performed PCA Analysis using the prcomp function apart of the FactoMineR package on quite a substantial dataset of 3000 x 500.
I have tried plotting the main Principal Components that cover up to 100% of cumulative variance proportion with a fviz_eig plot. However, this is a very large plot due to the large dimensions of the dataset. Is there any way in R to split a plot into multiple plots using a for loop or any other way?
Here is a visual of my plot that only cover 80% variance due to the fact it being large. Could I split this plot into 2 plots?
Large Dataset Visualisation
I have tried splitting the plot up using a for loop...
for(i in data[1:20]) {
fviz_eig(data, addlabels = TRUE, ylim = c(0, 30))
}
But this doesn't work.
Edited Reproducible example:
This is only a small reproducible example using an already available dataset in R but I used a similar method for my large dataset. It will show you how the plot actually works.
# Already existing data in R.
install.packages("boot")
library(boot)
data(frets)
frets
dataset_pca <- prcomp(frets)
dataset_pca$x
fviz_eig(dataset_pca, addlabels = TRUE, ylim = c(0, 100))
However, my large dataset has a lot more PCs that this one (possibly 100 or more to cover up to 100% of cumulative variance proportion) and therefore this is why I would like a way to split the single plot into multiple plots for better visualisation.
Update:
I have performed what was said by #G5W below...
data <- prcomp(data, scale = TRUE, center = TRUE)
POEV = data$sdev^2 / sum(data$sdev^2)
barplot(POEV, ylim=c(0,0.22))
lines(0.7+(0:10)*1.2, POEV, type="b", pch=20)
text(0.7+(0:10)*1.2, POEV, labels = round(100*POEV, 1), pos=3)
barplot(POEV[1:40], ylim=c(0,0.22), main="PCs 1 - 40")
text(0.7+(0:6)*1.2, POEV[1:40], labels = round(100*POEV[1:40], 1),
pos=3)
and I have now got a graph as follows...
Graph
But I am finding it difficult getting the labels to appear above each bar. Can someone help or suggest something for this please?
I am not 100% sure what you want as your result,
but I am 100% sure that you need to take more control over
what is being plotted, i.e. do more of it yourself.
So let me show an example of doing that. The frets data
that you used has only 4 dimensions so it is hard to illustrate
what to do with more dimensions, so I will instead use the
nuclear data - also available in the boot package. I am going
to start by reproducing the type of graph that you displayed
and then altering it.
library(boot)
data(nuclear)
N_PCA = prcomp(nuclear)
plot(N_PCA)
The basic plot of a prcomp object is similar to the fviz_eig
plot that you displayed but has three main differences. First,
it is showing the actual variances - not the percent of variance
explained. Second, it does not contain the line that connects
the tops of the bars. Third, it does not have the text labels
that tell the heights of the boxes.
Percent of Variance Explained. The return from prcomp contains
the raw information. str(N_PCA) shows that it has the standard
deviations, not the variances - and we want the proportion of total
variation. So we just create that and plot it.
POEV = N_PCA$sdev^2 / sum(N_PCA$sdev^2)
barplot(POEV, ylim=c(0,0.8))
This addresses the first difference from the fviz_eig plot.
Regarding the line, you can easily add that if you feel you need it,
but I recommend against it. What does that line tell you that you
can't already see from the barplot? If you are concerned about too
much clutter obscuring the information, get rid of the line. But
just in case, you really want it, you can add the line with
lines(0.7+(0:10)*1.2, POEV, type="b", pch=20)
However, I will leave it out as I just view it as clutter.
Finally, you can add the text with
text(0.7+(0:10)*1.2, POEV, labels = round(100*POEV, 1), pos=3)
This is also somewhat redundant, but particularly if you change
scales (as I am about to do), it could be helpful for making comparisons.
OK, now that we have the substance of your original graph, it is easy
to separate it into several parts. For my data, the first two bars are
big so the rest are hard to see. In fact, PC's 5-11 show up as zero.
Let's separate out the first 4 and then the rest.
barplot(POEV[1:4], ylim=c(0,0.8), main="PC 1-4")
text(0.7+(0:3)*1.2, POEV[1:4], labels = round(100*POEV[1:4], 1),
pos=3)
barplot(POEV[5:11], ylim=c(0,0.0001), main="PC 5-11")
text(0.7+(0:6)*1.2, POEV[5:11], labels = round(100*POEV[5:11], 4),
pos=3, cex=0.8)
Now we can see that even though PC 5 is much smaller that any of 1-4,
it is a good bit bigger than 6-11.
I don't know what you want to show with your data, but if you
can find an appropriate way to group your components, you can
zoom in on whichever PCs you want.
I want to present percentages over a 24h period in 15 min intervals as a bar plot.
When I use barplot(), the labels for those timepoints are more or less randomly chosen by R (depending on how I format the window. I know it's not random, but it's not what I want either). I would rather have them evenly spaced at 1 h intervals (that is every 4th bar).
I have searched extensively on this and know i can add labels later with axis() but I have not found a way to set which bars are labeled and which are left blank.
So here is an example. Sorry for the long lines:
x<-sample(1:100,96)
Labels<-c("09","09:15","09:30","09:45","10:00","10:15","10:30","10:45","11","11:15","11:30","11:45","12","12:15","12:30","12:45","13","13:15","13:30","13:45","14","14:15","14:30","14:45","15","15:15","15:30","15:45","16","16:15","16:30","16:45","17","17:15","17:30","17:45","18","18:15","18:30","18:45","19","19:15","19:30","19:45","20","20:15","20:30","20:45","21","21:15","21:30","21:45","22","22:15","22:30","22:45","23","23:15","23:30","23:45","00","00:15","00:30","00:45","01","01:15","01:30","01:45","02","02:15","02:30","02:45","03","03:15","03:30","03:45","04","04:15","04:30","04:45","05","05:15","05:30","05:45","06","06:15","06:30","06:45","07","07:15","07:30","07:45","08","08:15","08:30","08:45")
names(x)<-Labels
barplot(x)
I do not think you can force R to show every label if it does not have enough space. But at least if you want to add the labels every 1h, the following code should work :
x<-sample(1:100,96)
Labels<-c("09","09:15","09:30","09:45","10","10:15","10:30","10:45","11","11:15","11:30","11:45","12","12:15","12:30","12:45","13","13:15","13:30","13:45","14","14:15","14:30","14:45","15","15:15","15:30","15:45","16","16:15","16:30","16:45","17","17:15","17:30","17:45","18","18:15","18:30","18:45","19","19:15","19:30","19:45","20","20:15","20:30","20:45","21","21:15","21:30","21:45","22","22:15","22:30","22:45","23","23:15","23:30","23:45","00","00:15","00:30","00:45","01","01:15","01:30","01:45","02","02:15","02:30","02:45","03","03:15","03:30","03:45","04","04:15","04:30","04:45","05","05:15","05:30","05:45","06","06:15","06:30","06:45","07","07:15","07:30","07:45","08","08:15","08:30","08:45")
b=barplot(x,axes = F)
axis(2)
axis(1,at=c(b[seq(1,length(Labels),4)],b[length(b)]+diff(b)[1]),labels = c(Labels[seq(1,length(Labels),4)],"09"))
I'm working on trying to create a key for a heatmap, but as far as I know, I cannot use the existing tools for adding a legend since I've generated the colors myself (I manually turn a scaled variable into rgb values for a short rainbow ( [255,0,0] to [0,0,255] ).
Basically, all I want to do is use the rightmost 10th of the screen to create a rectangle with these 10 colors: "#0000FF", "#0072FF", "#00E3FF", "#00FFAA", "#00FF38", "#39FF00", "#AAFF00", "#FFE200", "#FF7100", "#FF0000"
with three numerical labels - at 0, max/2, and max
In essence, I want to manually produce an object that looks like a rudimentary heatmap color key.
As far as I know, split.screen can only split the screen in half, which isn't what I'm looking for. I want the graphic I already know how to produce to take up the leftmost 90% of the screen, and I want this colored rectangle to take up the other 10%.
Thanks.
EDIT: I greatly appreciate the advice about the best way to the the plot - that said, I still would like to know the best way to do the task originally asked - creating the legend by hand; I already am able to produce the exact heatmap graphic that I'm looking for - the false coloring wasn't the only problem with ggplot that I was having - it was just the final factor convincing me to switch. I need a non ggplot solution.
EDIT #2: This is close to the solution I am looking for, except this only goes up to 10 instead of accepting a maximum value as a parameter (I will be running this code on multiple data-sets, all with different maximum values - I want the legend to reflect this). Additionally, if I change the size of the graph, the key falls apart into disconnected squares.
Take a look at the layouts function (link). I think you want something like this:
layout(matrix(c(1,2), 1, 2, byrow = TRUE), widths=c(9,1))
## plot heatmap
## plot legend
I would also recommend the ggplot2 package and the geom_tile function which will take care of all of this for you.
Assuming your data is in a data frame with the x and y coordinates and heatmap value (e.g. gdat <- data.frame(x_coord=c(1,2,...), y_coord=c(1,1,...), val=c(6,2,...))) Then you should be able to produce your desired heat map plot with the following ggplot command:
ggplot(gdat) + geom_tile(aes(x=x_coord, y=y_coord, fill=val)) +
scale_fill_gradient(low="#0000FF", high="#FF0000")
To get your data into the following format you may want to look into the very useful reshape2 package.
Given a script no ggplot restriction on this answer here is how one could produce the plot with just base R.
colors <- c("#0000FF", "#0072FF", "#00E3FF", "#00FFAA", "#00FF38",
"#39FF00", "#AAFF00", "#FFE200", "#FF7100", "#FF0000")
layout(matrix(c(1,2), 1, 2, byrow = TRUE), widths=c(9,1))
plot(rnorm(20), rnorm(20), col=sample(colors, 20, replace=TRUE))
par(mar=c(0,0,0,0))
plot(x=rep(1,10), y=1:10, col=colors, pch=15, cex=7.1)
You may have to adjust the cex for your device.
I have a data set I'm trying to build a scatter plot from in R.
On the Y axis I've got CTR, on the x-axis I've got CPM and I'm trying to scale the size of each point by the volume of impressions.
I'm able to successfully plot this but the baseline size of the points is quite small and I'd like to specify a specific baseline size to use and then scale up from there based off the Volume data.
Here is my current code:
data_set <- ggplot(mopub_pubs_2, aes(x=CPM, y=CTR))
data_set + geom_point(aes(size=Volume))
I've looked through the ggplot documentation but can't find anything that might allow me to manipulate size of points this way. Is anyone aware of a way to do this?
You can use function scale_size_continuous() to change size of your points. Default range= for points is form 1 to 6 and your Volume values are scaled in this range but you can change it to some larger values, for example, from 5 to 12.
+ scale_size_continuous(range=c(5,12))
I have two related problems.
Problem 1: I'm currently using the code below to generate a histogram overlayed with a density plot:
hist(x,prob=T,col="gray")
axis(side=1, at=seq(0,100, 20), labels=seq(0,100,20))
lines(density(x))
I've pasted the data (i.e. x above) here.
I have two issues with the code as it stands:
the last tick and label (100) of the x-axis does not appear on the histogram/plot. How can I put these on?
I'd like the y-axis to be of count or frequency rather than density, but I'd like to retain the density plot as an overlay on the histogram. How can I do this?
Problem 2: using a similar solution to problem 1, I now want to overlay three density plots (not histograms), again with frequency on the y-axis instead of density. The three data sets are at:
http://pastebin.com/z5X7yTLS
http://pastebin.com/Qg8mHg6D
http://pastebin.com/aqfC42fL
Here's your first 2 questions:
myhist <- hist(x,prob=FALSE,col="gray",xlim=c(0,100))
dens <- density(x)
axis(side=1, at=seq(0,100, 20), labels=seq(0,100,20))
lines(dens$x,dens$y*(1/sum(myhist$density))*length(x))
The histogram has a bin width of 5, which is also equal to 1/sum(myhist$density), whereas the density(x)$x are in small jumps, around .2 in your case (512 even steps). sum(density(x)$y) is some strange number definitely not 1, but that is because it goes in small steps, when divided by the x interval it is approximately 1: sum(density(x)$y)/(1/diff(density(x)$x)[1]) . You don't need to do this later because it's already matched up with its own odd x values. Scale 1) for the bin width of hist() and 2) for the frequency of x length(x), as DWin says. The last axis tick became visible after setting the xlim argument.
To do your problem 2, set up a plot with the correct dimensions (xlim and ylim), with type = "n", then draw 3 lines for the densities, scaled using something similar to the density line above. Think however about whether you want those semi continuous lines to reflect the heights of imaginary bars with bin width 5... You see how that might make the density lines exaggerate the counts at any particular point?
Although this is an aged thread, if anyone catches this. I would only think it is a 'good idea' to forego translating the y density to count scales based on what the user is attempting to do.
There are perfectly good reasons for using frequency as the y value. One idea in particular that comes to mind is that using counts for the y scale value can give an analyst a good idea about where to begin the 'data hunt' for stratifying heterogenous data, if a mixed distribution model cannot soundly or intuitively be applied.
In practice, overlaying a density estimate over the observed histogram can be very useful in data quality checks. For example, in the above, if I were looking at the above graphic as a single source of data with the assumption that it describes "1 thing" and I wish to model this as "1 thing", I have an issue. That is, I have heterogeneous data which may require some level of stratification. The density overlay then becomes a simple visual tool for detecting heterogeneity (apart from using log transformations to smooth between-interval variation), and a direction (locations of the mixed distributions) for stratifying the data.