[R] Intersecting list vs rows in matrix
Erik Iverson
eriki at ccbr.umn.edu
Tue Aug 10 23:02:01 CEST 2010
GL wrote:
> Know that if I have List_1 and List_2 that I can check to see if the
> intersect via the code below:
>
> List _1:
> a, b, c, d, e, f, g
> List_2:
> z, y, x, w, v, u, b
> length(intersect(List_1, List_2)) > 0
> return = true
>
> If instead I wanted to check a dataframe that is a "list of lists," how
> would I do that by record without looping?
>
> List _1:
> a, b, c, d, e, f, g
>
> List_2:
> z, y, x, w, v, u, b
> y, z, w, v, v, u, m
> z, y, x, a, b, c
> .
> .
> .
>
> return
> true
> false
> true
*Please* use actual R code and objects to represent your examples, not
pseudo-code! I believe you may have some confusion about the difference
between lists and vectors in R. A data.frame is a list, but not a "list
of lists".
Since you haven't given a reproducible example, it's hard for me to know
exactly what you want.
Assume a data.frame df1 composed of all character data, and a character
vector cv to match against.
apply(df1, 1, function(x) length(intersect(x, cv)) > 0)
may do what you want.
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