How to plot polar coordinates in R?

r polar-coordinates parametric-equations
Athul picture Athul · Mar 22, 2015 · Viewed 11.5k times · Source

Suppose that (x(t),y(t)) has polar coordinates(√t,2πt). Plot (x(t),y(t)) for t∈[0,10].

There is no proper function in R to plot with polar coordinates. I tried normal plot by giving, x=√t & y=2πt. But resultant graph was not as expected.

I got this question from "Introduction to Scientific Programming  and Simulation using r"and the book is telling the plot should be spiral.

Answer

IRTFM picture IRTFM · Mar 22, 2015

Make a sequence:

t <- seq(0,10, len=100)  # the parametric index
# Then convert ( sqrt(t), 2*pi*t ) to rectilinear coordinates
x = sqrt(t)* cos(2*pi*t) 
y = sqrt(t)* sin(2*pi*t)
png("plot1.png");plot(x,y);dev.off()

enter image description here

That doesn't display the sequential character, so add lines to connect adjacent points in the sequence:

png("plot2.png");plot(x,y, type="b");dev.off()

enter image description here

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