Question

In R, let’s say we have a vector
area = c(rep(c(26:30), 5), rep(c(500:504), 5), rep(c(550:554), 5), rep(c(76:80), 5)) and another vector yield = c(1:100).
Now, say I want to index like so:

> yield[area==27]
[1]  2  7 12 17 22
> yield[area==501]
[1] 27 32 37 42 47

No problem, right? But weird things start happening when I try to index it by using c(A, B). (and even weirder when I try c(min:max) …)

> yield[area==c(27,501)]
[1]  7 17 32 42

What I’m expecting is of course the instances that are present in both of the other examples, not just some weird combination of them. This works when I can use the pipe OR operator:

> yield[area==27 | area==501]
 [1]  2  7 12 17 22 27 32 37 42 47

But what if I’m working with a range? Say I want index it by the range c(27:503)? In my real example there are a lot more data points and ranges, so it makes more sense, please don’t suggest I do it by hand, which would essentially mean:

yield[area==27 | area==28 | area==29 | ... | area==303 | ... | area==500 | area==501]

There must be a better way…

Answer 1

You want to use %in%. Also notice that c(27:503) and 27:503 yield the same object.

> yield[area %in% 27:503]
 [1]   2   3   4   5   7   8   9  10  12  13  14  15  17
[14]  18  19  20  22  23  24  25  26  27  28  29  31  32
[27]  33  34  36  37  38  39  41  42  43  44  46  47  48
[40]  49  76  77  78  79  80  81  82  83  84  85  86  87
[53]  88  89  90  91  92  93  94  95  96  97  98  99 100