Plot conditional colors based on rows

Question

I have two data.frames called outlier and data.

outlier just keeps row numbers which needs to be coloured. data has 1000 data. It has two columns called x and y. If row number exists in outliers I want dots in plot to be red, otherwise black

plot(data$x, data$y, col=ifelse(??,"red","black"))

Something should be in ?? .

long story short, if I print `outlier .[1] 178 318 333 556 611 615 716 840 965` — Etibar - a tea bar, Feb 18 '16 at 19:15
I don't know why you need how I created outliers. But in case. `outliers = which( data$x > (quantile(data$x,0.5) +IQR) )` — Etibar - a tea bar, Feb 18 '16 at 19:18
Unless you need it for something else, skip creating `outlier`: `plot(x, y, col = ifelse( x > ..., "red", "black"))`. Better yet [skip `ifelse`](http://stackoverflow.com/questions/16275149/does-ifelse-really-calculate-both-of-its-vectors-every-time-is-it-slow) by doing: `c("black", "red")[(x > ...) + 1L]` — MichaelChirico, Feb 18 '16 at 19:38

JHowIX · Answer 1 · 2016-02-18T19:46:54.933

1

I think this can be accomplished by creating a new color column in your data frame:

data$color <- "black"

Then set the outliers to a different value:

data[outlier,"color"] <- "red"

I dont have your exact data but I think I got something similar to what you wanted using the following:

outlier <- c(1, 2, 7, 9)
data <- data.frame(x=c(1,2,3,4,5,6,7,8,9,10),
                   y=c(1,2,3,4,5,6,7,8,9,10))
data$color <- "black"
data[outlier,"color"] <- "red"
data
    x  y color
1   1  1   red
2   2  2   red
3   3  3 black
4   4  4 black
5   5  5 black
6   6  6 black
7   7  7   red
8   8  8 black
9   9  9   red
10 10 10 black

Finally plot using the new value in data:

plot(data$x, data$y, col=data$color)

Results in:

edited Feb 18 '16 at 19:46

answered Feb 18 '16 at 19:35

JHowIX

1,683
1
20
38

It produces right colors, but it is a little bit longer. I would like ot achieve it by `ifelse` or simpler version. Again, yes it works. Thanks for you time – Etibar - a tea bar Feb 18 '16 at 19:51
Hi Etibar, I am a little confused by your comment. My solution is 2 lines. Are you saying you will only accept an answer that is 0 or 1 lines in length? – JHowIX Feb 18 '16 at 19:54

score 1 · Accepted Answer · answered Feb 18 '16 at 23:57

1

Hi this way works for me using ifelse, let me know what you think:

outlier <- sample(1:100, 50)
data <- data.frame(x = 1:100, y = rnorm(n = 100))
plot(
  data[ ,1], data[ ,2]
  ,col = ifelse(row.names(data) %in% outlier, "red", "blue")
  ,type = "h"
)

answered Feb 18 '16 at 23:57

Alex Thompson

506
5
13

Plot conditional colors based on rows

2 Answers2