r - Create a function from a vector to another -
i have 2 vectors:
x <- c(-2.0,-1.75,-1.50,-1.25,-1.00,-0.75,-0.50,-0.25,0.00,0.25,0.50,0.75,1.00,1.25,1.50,1.75,2.00,2.25,2.50,2.75) y <- c(37.0000,24.1602,15.06250,8.91016,5.00000,2.72266,1.56250,1.09766,1.00000,1.03516,1.06250,1.03516,1.00000,1.09766,1.56250,2.72266,5.00000,8.91016,15.06250,24.16016) i trying create function given number vector x, returns corresponding y value(same index). example, func(-2.0) should return 37.0000.
currently have super ugly function don't think supposed do:
func1 <- function(x) { if (x==-2.0) {return (37.0000)} else if (x==-1.75){return (24.1602)} else if (x==-1.50){return (15.06250)} else if (x==-1.25){return (8.91016)} else if (x==-1.00){return (5.00000)} else if (x==-0.75){return (2.72266)} else if (x==-0.50){return (1.56250)} else if (x==-0.25){return (1.09766)} else if (x==0.00){return (1.00000)} else if (x==0.25){return (1.03516)} else if (x==0.50){return (1.06250)} else if (x==0.75){return (1.03516)} else if (x==1.00){return (1.00000)} else if (x==1.25){return (1.09766)} else if (x==1.50){return (1.56250)} else if (x==1.75){return (2.72266)} else if (x==2.00){return (5.00000)} else if (x==2.25){return (8.91016)} else if (x==2.50){return (15.06250)} else if (x==2.75){return (24.16016)} else {return (inf)} }
for exact matching:
foo = function(u) {res=y[pmatch(u,x)];ifelse(is.na(res), inf, res)} #> foo(-2) #[1] 37 #> foo(-1.8) #[1] inf #> foo(-4) #[1] inf not sure need beware can use linear interpolation (you can put method constant instead of linear):
foo = approxfun(x,y, yleft=inf, yright=inf) #> foo(-2) #[1] 37 #> foo(-1.8) #[1] 26.72816 #> foo(-4) #[1] inf in last case, value not inf in boundary domain defined x.
Comments
Post a Comment