I am attempting to project data onto a plot in R and see the correlation between the points. I have added a line to let the reader see the connection between these points. I am however stumped when it comes to inputting arrows to show the direction of the line. Rddproj was just an arbitrary name given to the data. Three sets of x and y coordinates are plotted x=c(-0.7159425, -0.8129311, -0.7392371); y=0.7743088, 0.7732762, 0.7490996) Here is the example below.
x<-rddproj[1:3,1]; y<-rddproj[1:3,2]
plot(x,y)
My concern is that the second group of coordinates is the greatest negative point on the x-axis. In drawing a line with arrows, the arrow will most likely point towards this point, when it should be forming a V with that point in the middle. Is it possible to plot an arrow to reflect the placement of points in a group and not just the most positive point to the most negative point or vice versa?
The arrows function ( a modified segments function) is used for this purpose (to the extent that I understand the question) in base R:
# fixed your assignment code.
plot(NA, xlim=range(x), ylim=range(y) )
arrows(head(x,-1),head(y,-1),tail(x,-1), tail(y,-1), angle=30)
An alternative reading of your question would have the glaringly obvious solution : plot(x,y) which I hope is not what you were asking since that should have been satisfactory.
Related
I am trying to plot the solution curve from this page:
dynamicalsystem
But, I can't draw the arrow in the curve pointing to the origin, and the curve is not spiraling as well. Is something wrong with my code?
using MTH229, ForwardDiff, Plots, LaTeXStrings, SymPy
gr()
t = range(0, stop=21, length=10000)
x = #. exp(-2t)*cos(t)
y = #. exp(-2t)*sin(t)
plot(x, y, arrow = :closed, label=L"x(t)",
xlims=(-0.1,1), ylims=(-0.1,0.21))
You do not see a spiral, because the plot you have linked is not accurate (i.e. it has a wrong scale - most likely for didactic purposes). You can see that you have a spiral, by e.g. plotting the angle of the point plot(t, angle.(x + im * y)). The problem is that the plot absolute value of the points you plot gets very small very fast so these spirals are not visible.
Now the other issue is how to plot the arrow. The arrow in your case is just not visible because it is plotted at the end of your curve. I think (but maybe there are better ways to do it) that the simplest solution to pick a place to add it separately. For example after doing an initial plot add plot!(x[240:241], y[240:241], arrow=:closed) will add an extra arrow in the segment of your curve and the arrow will be visible (you just need to decide on the color of the arrow).
I am trying to plot individual data points on a line plot I already made as follows:
p=plot('3.29*exp(-17.4*(x^2))-0.908',xrange=[0.,1.],yrange=[-1.,1.5])
I first tried overplotting a point like this but nothing appears on the graph
estimate1=plot([0.549],[0.755],overplot=1)
When I give the plot function two points to overplot by adding another set of x and y values in input vectors, it connects them.
estimate=plot([0.349,0.9595],[0.555,0.9995],overplot=1)
How can I (over)plot the points without them being connected?
You should be able to set linestyle = 6 which will plot without the line.
I found a way around the problem I was having. After choosing a symbol for the points I wanted to show, I simply set the transparency of the line connecting them to 100 and the symbol transparency to 0.
estimate1.symbol='diamond'
estimate1.transparency=100
estimate1.sym_transparency=0
The work around is not elegant, but it works.
I've come up with a graph (a scatterplot) of the log(1+inf) (inf = number of people infected with a given disease on the y-axis against one of the explanatory variables, in this case, the populational density (pop./km²; x-axis) on my model. The log transformation was used merely for visualization, because it spreads the distribution of the data and allows for more aesthetically appealing plots. Basically, what I want is both axis to show the value of that same variable before the log transformation. The dots need to be plotted like plot(log(1+inf),log(populational_density), but the number on the axis should refer to plot(inf,populational_density). I've provided a picture of my graph with some manual editing on the y-axis to show you the idea of what I want.
The numbers in red would be the 'inf' values equivalent to log(inf);
Please, bear in mind that those values in red do not correspond to reality.
I understand the whole concept of y = f(x), but i've been asked to provide it. Is this possible? I'm using the ggplot2package for plotting.
Assume I want to plot the following dataframe:
df <- data.frame(expand.grid(1:10,1:10),rep(10,100))
colnames(df) <- c("x","y","z")
with the lattice wireframe() function:
wireframe(z~x*y,df,colorkey=TRUE,drape=TRUE)
How do I get it to plot the given coordinates? I would assume it has something to do with having to scale/adjust the z-axis as the automatic scaling within wireframe is probably confused by all z-coordinates being equal.
This is from the help page scales section: "The most common use for this argument is to set arrows=FALSE, which causes tick marks and labels to be used instead of arrows being drawn (the default)." So just add that as a list value to 'scales':
wireframe(z~x*y,df,colorkey=TRUE,drape=TRUE,
scales=list(arrows=FALSE), zlim=c(0,10.1))
The failure of wireframe to display anything when the plotted plane is at one of the extremes seems to be at least "unexpected behavior" if not a bug. I suspect you would not see this in real data. Your use of drape doesn't make much sense since the entire data-plane plane gets displayed at the white midpoint. (Again this is probably not a problem if you have something other than this pathological example.)
Just add a zlim argument.
wireframe(z~x*y,df,colorkey=TRUE,drape=TRUE, zlim=c(0,20))
I'm using plotrix package to draw circles.
And I don't get what is wrong with my code... :-(
I have three points. The first point (1,1) should be the center of the circle. The following two points (1,4) and (4,1) have the same distance/radius to the center.
So the circle in the plot should go through these points, right?
And I don't know why the circle looks wrong. Is there an explanation?
p1 <- c(1,1)
p2 <- c(4,1)
p3 <- c(1,4)
r <- sqrt(sum((p1-p2)^2))
plot(x=c(p1[1], p2[1], p3[1]),
y=c(p1[2], p2[2], p3[2]),
ylim=c(-5,5), xlim=c(-5,5))
draw.circle(x=p1[1], y=p1[2], radius=(r))
abline(v=-5:5, col="#0000FF66")
abline(h=-5:5, col="#0000FF66")
Take a look at the produced output here
As #Baptiste says above, you can use plot(...,asp=1). This will only work if your x and y ranges happen to be the same, though (because it sets the physical aspect ratio of your plot to 1). Otherwise, you probably want to use the eqscplot function from the MASS package. A similar issue arises whenever you try to do careful plots of geometric objects, e.g. Drawing non-intersecting circles
This plot is produced by substituting MASS::eqscplot for plot in your code above:
Note that depending on the details of what R thinks about your monitor configuration etc., the circle may look a bit squashed (even though it goes through the points) when you plot in R's graphics window -- it did for me -- but should look OK in the graphical output.