How do I triple a column?

Question

How do I triple a column?

I am wondering how to multiply my data based on the appearance of the tripartite in the column.

t <- c(1,1,2,2,3,3,4,4,5,5,5,6,6,7,7,7,8,8)

mydf <- data.frame(t, 1:18)

I want to be able to grab only rows that match the triplet in column t, so that I can form a new dataframe of only those rows. It will look like this, where p is the vector of the strings I'm looking for:

p <- c(9,10,11,14,15,16)

myidealdf[p,]

Sorry if it's not clear, this is my first post

+3

r

Michael swift 02 Aug 17 at 23:43

source to share

2 answers

Using the function rle

.

which(t %in% with(rle(t), values[lengths==3]))
[1]  9 10 11 14 15 16

0

Pierre lafortune 03 Aug 17 at 0:11

source to share

Shaun wilkinson · Accepted Answer · 2017-08-03T00:07:06+0000

This should do it

keeps <- unique(t)[table(as.factor(t)) == 3]
keeps <- t %in% keeps
mydf <- mydf[keeps, ]

How do I triple a column?

More articles: