Extract the top first row from dataframe in R

Question

In dataframe df (sorted by column two), I need to select first one row where two > 7 and extract its data from column four:

       one two three four
 [1,]   1   6    11   16
 [2,]   2   7    12   17
 [3,]   3   8    11   18
 [4,]   4   9    11   19
 [5,]   5  10    15   20

Basically i need this row:

 [3,]   3   8    11   18

Answer 1

Here is an option using which.max

df[which.max(df$two > 7), ]
#  one two three four
#3   3   8    11   18

---

Sample data

df <-read.table(text =
    "one two three four
 1   6    11   16
 2   7    12   17
 3   8    11   18
 4   9    11   19
 5  10    15   20", header = T)

Answer 2

One liner assuming your data.frame is called df

df[head(which(df$two > 7), 1), ]

In case you need more than one top rows, just update that 1 to any number.

Answer 3

You can use sqldf package. If the name of the data frame is df :

library(sqldf)
result <- sqldf("SELECT * FROM df 
                 WHERE two > 7 
                 ORDER BY two
                 LIMIT 1")

Answer 4

You can use tidyverse package

d<-data.frame(c(1,2,3,4,5),
              c(6,7,8,9,10),
              c(11,12,11,11,15),
              c(16,17,18,19,20))

d<-`colnames<-`(d,c('one','two','three','four'))
library(dplyr)
d%>%
  arrange(two)%>%
  filter(two>7)%>%
head(1)

Output:

 one two three four
1   3   8    11   18