Select points by drawing a freehand gate

Wajid Jawaid

2016-12-15

gatepoints provides an easy to use function, fhs (freehand select) for gating or selecting points freehand on a plot. If using from RStudio please use X11 display for a better user experience. Take the simple plot below:

x <- data.frame(x=1:10, y=1:10, row.names = 1:10)
## If you are using RStudio do X11() first.
plot(x, pch = 16, col = "red")
Simple plot.

Simple plot.

library(gatepoints)
selectedPoints <- fhs(x, mark = TRUE)

To select an arbitrarily complex region run the above commands and proceed as follows:

  1. Mark region of your choice by left clicking around your region of interest.
  2. Close polygon by right clicking. On the Windows platform click stop after right clicking.
Selected points

Selected points

The points can be marked as defined by the user with additional parameters passed to the points function. The names of the points as given by the rownames of the data frame x will be returned in selectedPoints. Additionally the points selected for the gate will be returned as the gate attribute.

selectedPoints
## [1] "4" "5" "7"
## attr(,"gate")
##          x        y
## 1 6.099191 8.274120
## 2 8.129107 7.048649
## 3 8.526881 5.859404
## 4 5.700760 6.716428
## 5 5.605314 5.953430
## 6 6.866882 3.764390
## 7 3.313575 3.344069
## 8 2.417270 5.217868