Determine repeating numbers in a string in R

Question

I am trying to identify column values in a data frame that have repeating number sequence. For instance

> df
   ColA
1 66046
2 73947
3 67456
4 67217
5 66861
6 67658

I want to return 66046, 66861 as 6 appears in succession. I have tried the following...

df %>% filter(str_detect(as.String(df[1]), "[66]"))  #with and without the squared brackets.
df[unlist(gregexpr("[6]{2}[[:digit:]]", df[1])), ][1]

Obvious to say, this doesn't work. Any help is appreciated.

Thanks

Answer 1

We can specify the count with

library(dplyr)
library(stringr)
df %>%
   filter(str_detect(ColA, "6{2,}"))

-output

#   ColA
#1 66046
#5 66861

data

df <- structure(list(ColA = c(66046L, 73947L, 67456L, 67217L, 66861L, 
67658L)), class = "data.frame", row.names = c("1", "2", "3", 
"4", "5", "6"))

Answer 2

Use

library(dplyr)
library(stringr)
df %>%
   filter(str_detect(ColA, "(\\d)\\1"))

See proof

NODE	EXPLANATION
(	group and capture to \1:
\d	digits (0-9)
)	end of \1
\1	what was matched by capture \1

Answer 3

Late to the party but here's a solution in base R:

df[which(grepl("(\\d)\\1", df$ColA)),]