CODEWITHSUNDEEP
rdplyr
Ramiro Magno
Ramiro Magno

Reputation: 3175

how to dplyr filter match?

I guess this might be a rather simple question, but how to do this (base R):

df <- data.frame(x=10:1,y=(1:10)^2)
df[match(c(3,5,7), df$x),]

in idiomatic dplyr parlance:

tb <- dplyr::as.tbl(df)
dplyr::filter(tb, ??? )

or, in other words, what should go into ??? to make it functionally equivalent to the first snippet? Please note that the order of rows in resulting dataframe/tibble is relevant.

Upvotes: 1

Views: 1469

Answers (2)

mpalanco
mpalanco

Reputation: 13570

Using filter as well:

df %>% 
  filter( x %in% c(3, 5, 7)) %>% 
  group_by(x) %>% 
  slice(1)

Output:

  x  y
1 7 16
2 5 36
3 3 64

sqldfpackage:

library(sqldf)
sqldf('SELECT *
      FROM df 
      WHERE x IN (3, 5, 7)
      GROUP BY x
      LIMIT 3')

Upvotes: 1

Ramiro Magno
Ramiro Magno

Reputation: 3175

As suggested by @RichScriven: use dplyr::slice(df, match(c(3, 5, 7), x)) instead of dplyr::filter.

Upvotes: 5

Related Questions