everybody.
I am writing this question because I need your help to do a graphical representation in R. I would like to do a graphic as a coordinate system (two variables) and another variable representing the volume (size) of the points.
You can see an example:pxfolioplotbcgmatrix
Thank you!
Try ?symbols function
x <- 1:5
y <- 5:1
r <- seq(2, 10, 2)
symbols(x, y, circles=r, fg="white", bg="red")
Related
I need to create something like a spider chart in R without using any libraries. That’s my code for now. It creates a figure with points number equal to the length of vector ‘a’. However, I’d like each point to be at the distance from the coordinates center equal to a respective number in a vector, for example one point at a distance 1, another at 2, so on. Is it possible to do so?
a <- 1:6
angle <- seq(0, 2*pi, (2*pi)/length(a))
x <- cos(angle)
y <- sin(angle)
plot(x, y,
type = "l")
See ?stars:
a <- 1:6
stars(matrix(a, nrow=1), scale=FALSE)
For future reference, using R's built-in help search would have found this with ??spider
I was working with 3 vectors x , y , z , each of length N (Assume N to be some large natural number, say 20000). In order to visualize this, I was able to plot this easily using the following R code :
library("plot3D")
lines3D(x, y, z, type = "l")
Now, I was thinking if we can make a little 3D animation (i.e. a 3D GIF) from the vectors x , y , z. Is it possible in R ?
NOTE : I've previously done 2D GIFs in R, with the help of packages like ggplot2 , gganimate , magick etc. However, I'm curious whether the same thing can be done for 3D data. Thanks in advance.
It is very simple to create .gif with the animation package (note it requires ‘ImageMagick’ or ‘GraphicsMagick’ to run). After the installation, you could do something like this (I assume that you want to display your plot with different point of view):
library(plot3D)
library(animation)
x <- runif(1000)
y <- x*2+runif(1000)
z <- sample(1:10,length(x),replace = T)*x/y
ani.options(interval=0.5,nmax=35)
saveGIF(for(t in seq(0,360,10)){
lines3D(x, y, z, type = "l",theta=t)
}, movie.name = "animation.gif")
I have instruction for R console:
plot(1:1000, some_function(1000,1/2,500, type='l')
Can someone explain to me what 1:1000 means? I tried to put some other input instead of 1:1000, for example 1:100 but then it won't work.
I understand that 1:1000 means it will iterate from 1 to 1000, but what does that mean as a plot argument?
Thanks in advance.
It means a vector with the elements from 1 to 1000; therefore, a 1000-element vector.
For the plot function, the first argument corresponds to the x coordinates of the points to be added. Hence, 1:1000 means that the data points will have x coordinates 1, 2, ..., 1000
I'm looking into plotting functions and I've run into persp and curve but I'm not able to follow them to plot a 2D function.
They are for surface plots, yes?
If I had a function like x^2 + y^2 [x,y] in [-3,3] how do I go about it?
Any links will be much appreciated and critique on existing packages (if multiple) ? gold.
Thanks.
To use persp, you need to supply values of x, values of y, and values of z for each combination of x and y. The easiest way to do this is to define x and y and then use outer to create a matrix that crosses x and y. You need to specify the way the two variables should be combined as the third argument to outer, in this case the function +:
x <- seq(-3,3,length.out=100)
y <- seq(-3,3,length.out=100)
z <- outer(x^2,y^2,`+`)
persp(x,y,z, col='blue')
You may also be interested in rotating the results. Here are some examples using the theta parameter:
par(mar=c(1,1,1,1))
layout(matrix(1:4, nrow=2))
s=lapply(c(0,30,60,90), function(t) persp(x,y,z, col='blue', theta=t))
EDIT: I understand from your comment you would like a 2D representation of this surface. The easiest way to get that in base R is with image of your z matrix:
image(z)
I'm wondering if it is possible to caclulate the area within a contour in R.
For example, the area of the contour that results from:
sw<-loess(m~l+d)
mypredict<-predict(sw, fitdata) # Where fitdata is a data.frame of an x and y matrix
contour(x=seq(from=-2, to=2, length=30), y=seq(from=0, to=5, length=30), z=mypredict)
Sorry, I know this code might be convoluted. If it's too tough to read. Any example where you can show me how to calculate the area of a simply generated contour would be helpful.
Thanks for any help.
I'm going to assume you are working with an object returned by contourLines. (An unnamed list with x and y components at each level.) I was expecting to find this in an easy to access location but instead found a pdf file that provided an algorithm which I vaguely remember seeing http://finzi.psych.upenn.edu/R/library/PBSmapping/doc/PBSmapping-UG.pdf (See pdf page 19, labeled "-11-") (Added note: The Wikipedia article on "polygon" cites this discussion of the Surveyors' Formula: http://www.maa.org/pubs/Calc_articles/ma063.pdf , which justifies my use of abs().)
Building an example:
x <- 10*1:nrow(volcano)
y <- 10*1:ncol(volcano)
contour(x, y, volcano);
clines <- contourLines(x, y, volcano)
x <- clines[[9]][["x"]]
y <- clines[[9]][["y"]]
level <- clines[[9]][["level"]]
level
#[1] 130
The area at level == 130 (chosen because there are not two 130 levels and it doesn't meet any of the plot boundaries) is then:
A = 0.5* abs( sum( x[1:(length(x)-1)]*y[2:length(x)] - y[1:(length(x)-1)]*x[2:length(x)] ) )
A
#[1] 233542.1
Thanks to #DWin for reproducible example, and to the authors of sos (my favourite R package!) and splancs ...
library(sos)
findFn("area polygon compute")
library(splancs)
with(clines[[9]],areapl(cbind(x,y)))
Gets the same answer as #DWin, which is comforting. (Presumably it's the same algorithm, but implemented within a Fortran routine in the splancs package ...)