R: Is it possible to write a condition like "if this statement does not throw an error"-CodePudding

I am using a function called curve_intersect under the package reconPlots to figure out whether two plotted lines intersect and what the intersection coordinates are. This is a link to the function: https://rdrr.io/github/andrewheiss/reconPlots/src/R/curve_intersect.R

Depending on what the line is, the function can throw an error if there are no points of intersection.

This is an example of a line which would throw an error:

line1 <- data.frame(x = c(1,2), y = c(1000,750))
line2 <- data.frame(x<-c(1,2,3,4), y = y<-c(60,90,800,1000))
curve_intersect(line1, line2)

And an example of one that would return the points of intersection:

line1 <- data.frame(x = c(1,2,3,4), y = c(1000,750,200,100))
line2 <- data.frame(x<-c(1,2,3,4), y = y<-c(60,90,800,1000))
curve_intersect(line1, line2)

I am writing a function where I would like to run a statement only if there is a point of intersection. i.e. I would like to run it if curve_intersect(line1, line2) does not throw an error.

Is there a simple way to run something only if it doesn't throw an error or is there another way I could run my code only if there is an intersection?

CodePudding user response：

You could use tryCatch(). Here is an example which won't stop the code, but will print the error:

tryCatch(curve_intersect(line1, line2),
         error = function(e) print(e))

To further answer your question, you could return NULL when the function fails. If the curve_intersect() does not fail and does not return NULL, run what is inside the conditional statement:

c_i <- tryCatch(curve_intersect(line1, line2),
                error = function(e) NULL)

if (!is.null(c_i)) {
  fun()
}