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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?

user438383
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locket
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1 Answers1

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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()
}
bdbmax
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