(This article was first published on

**Keep on Fighting! » R Language**, and kindly contributed to R-bloggers)Today Ruya Gokhan Kocer asked me how to use the R function `identify()`

in off-screen graphics devices. Actually it’s pretty easy as long as we obtain the list returned by `identify(pos = TRUE)`

. For example,

# open a windows device x11() x = rnorm(20) y = rnorm(20) plot(x, y) # identify 5 points id = identify(x, y, n = 5, pos = TRUE) # $ind # [1] 2 6 10 14 16 # # $pos # [1] 1 1 4 4 1 # then open a bitmap device png("identify.png") plot(x, y) # use the information from above mouse click text(x[id$ind], y[id$ind], id$ind, pos = id$pos) dev.off()

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