CODEWITHSUNDEEP
rplotarrows
Peng
Peng

Reputation: 5

Difficulties with adding arrows to plot in R

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)

Simple Plot of Data

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?

Upvotes: 0

Views: 1313

Answers (1)

IRTFM
IRTFM

Reputation: 263352

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)

enter image description here

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.

Upvotes: 1

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