CODEWITHSUNDEEP
rdata.table
user7613376
user7613376

Reputation:

between vs inrange in data.table

In R's data.table, when should one choose between %between% and %inrange% for subsetting operations? I've read the help page for ?between and I'm still scratching my head as to the differences. 

library(data.table)
X = data.table(a=1:5, b=6:10, c=c(5:1))


> X[b %between% c(7,9)]
   a b c
1: 2 7 4
2: 3 8 3
3: 4 9 2
> X[b %inrange% c(7,9)]
   a b c
1: 2 7 4
2: 3 8 3
3: 4 9 2

They look the same to me. Could someone please explain why there exist both operations?

Upvotes: 8

Views: 5206

Answers (1)

user7613376
user7613376

Reputation: 

> X
   a  b c
1: 1  6 5
2: 2  7 4
3: 3  8 3
4: 4  9 2
5: 5 10 1

Using the example in the comments:

> X[a %between% list(c, b)]
   a  b c
1: 3  8 3
2: 4  9 2
3: 5 10 1
> X[a %inrange% list(c, b)]
   a  b c
1: 1  6 5
2: 2  7 4
3: 3  8 3
4: 4  9 2
5: 5 10 1

It seems between looks at each row individually and checks to see if the value in a is such that c <= a <= b for that row.

inrange looks for the smallest scalar value in c, say cmin and the largest scalar value in b, bmax, forming a range [cmin, bmax], and then checks to see if a lies in this range [cmin, bmax], for each row in the a column.

Upvotes: 8

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