CODEWITHSUNDEEP
rfunctionlapply
Carlos
Carlos

Reputation: 948

Apply an own function to list in R

I'm starting with R. I've taken a 2d sample in a list. This list contains 2 vectors with 100 elements either one:

muestra2d <- take_samples(2, 100, c(-100, 100));

I've a function that calculates coefficients m and b of a line in the form y=mx+b in a box in a given range.

vars <- sim_line(c(-100, 100))

Ok, my aim is apply a function f(x,y)=y-ax-b where x is an element of muestra2d[1], y is an element of muestra2d[2], a is the slope of the line (m) and b is the offset of the line. The function must label the sample with the sign of the function for each pair of values (x,y).

I've tried it with this line 

result <- lapply(muestra2d, function(x,y) (y-(vars[5]*x)-vars[6]))

thinking lapply takes an element from the first vector of the list and copies it in x, doing the same for y and applying the function to this values, but it isn't a good idea.

How I can do this? How I can plot the line, points and negative points with another color at the same time?

Upvotes: 0

Views: 210

Answers (1)

bgoldst
bgoldst

Reputation: 35324

set.seed(1L);
take_samples <- function(sample.num,elem.num,box) lapply(seq_len(sample.num),function(i) runif(elem.num,box[1L],box[2L]));
sim_line <- function(box) c(1,0);
box <- c(-100,100);
muestra2d <- take_samples(2L,100L,box);
vars <- sim_line(box);
signs <- sign(muestra2d[[2L]] - vars[1L]*muestra2d[[1L]] - vars[2L]);
par(xaxs='i',yaxs='i');
plot(NA,xlim=box,ylim=box,xlab='x',ylab='y',main='plot');
abline(vars[2L],vars[1L]);
with(setNames(muestra2d,c('x','y')),{
    points(x[signs>=0],y[signs>=0],col='green');
    points(x[signs<0],y[signs<0],col='red');
});

plot

Upvotes: 1

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