Другое базовое решение R
df <- within(df,
Num_repeats <- sapply(gsub("\\D","",Number,perl = TRUE),
function(x) (u<-max(rle(utf8ToInt(x))$lengths))*(u>1)))
или более простое
df <- within(df,
Num_repeats <- sapply(Number,
function(x) (u<-max(rle(utf8ToInt(x))$lengths))*(u>1)))
такое, что
> df
Number Num_repeats
1 18.25328700000000026193 9
2 18.09606604359100042883 3
3 17.95982782048729065186 0
DATA
df <- structure(list(Number = c("18.25328700000000026193", "18.09606604359100042883",
"17.95982782048729065186")), row.names = c(NA, -3L), class = "data.frame")