Intersect Vectors

[michaelgloven]

Hi,

Does anyone know how to intersect 2 vectors to resolve the following use case with vectors of different lengths?

d$Id <- c(1,2,3,4,5)
s$Id <- c(3,5)

I want to return a new value which is the length of d (five) with a new value d$color where if 3 or 5 the color is red else the color is steelblue. Thus, the final vector I'm looking for is:

d$color <- c(steelblue, steelblue, red, steelblue, red)

I tried the %in% within ifelse statements without success.

thank you

[AlexisW]

@michaelgloven

I tried the %in% within ifelse statements without success.

How did it fail? I'd expect it to work, what code did you use, and what error message did you get?

[nirgrahamuk]

its not clear how your text description involving d involves s at all, what is the relevance of s to this ?

[stkrog]

How about this:

d$color = rep("steelblue", length(d$Id))
d$color[d$Id %in% s$Id]="red"

Cheers
Steen

[michaelgloven]

Thanks all, as a relative newbie to R my use case is taking a dataframe 'd' and subsetting this based on selected rows in a DT table in shiny using the selected rows feature. All of this works fine, I have a large dataframe d and a subset of d called s. I then have a ggplot of points showing all d and want to highlight the selected points from the table which are s in d. I know how to do all of this using DT and ggplot, and for reasons beyond this post I don't want to use the brush feature.

I simply want to have a new column in d which indicates 'color' which will then highlight my points in the ggplot. Hence, I want to set the color of my points c(1,2,3,4,5....) in d based on what is selected in s c(3,5...). So, I'd like 1,2,4 to be steelblue and 3 and 5 to be red.

Here's a simple example

d <- data.frame(Id = c(1,2,3,4,5))
s <- data.frame(Id = c(3,5))

x1 <- if(s$Id %in% d$Id){"red"}else{"steelblue"}
error: the condition has length > 1 and only the first element will be used
x1
[1] "red"

or try
x2 <- ifelse(s$Id %in% d$Id,"red","steelblue")
x2
[1] "red" "red"

Thanks again!

[AlexisW]

You basically have it: the first one doesn't work because if{}else{} is not vectorized. The second approach is correct, you just need to look if d is in s, rather than the opposite.

d <- data.frame(Id = c(1,2,3,4,5))
s <- data.frame(Id = c(3,5))

x1 <- ifelse(d$Id %in% s$Id, "red", "steelblue")
x1
#> [1] "steelblue" "steelblue" "red"       "steelblue" "red"

^{Created on 2020-11-26 by the reprex package (v0.3.0)}

[michaelgloven]

Appreciate your help, and continued learning!