how to find the row number of similar strings - r

Question

My data is huge but I want to know the row number of similar strings
df<- structure(list(x = structure(c(5L, 5L, 5L, 5L, 1L, 1L, 3L, 5L,
5L, 6L, 6L, 2L, 2L, 2L, 2L, 4L, 4L, 4L, 3L), .Label = c("AJ5ter2",
"al-1Tter2", "AY9ter2", "CY-Yter2", "LK2ter2", "YY49ter2"), class = "factor")), class = "data.frame", row.names = c(NA,
-19L))
a desire output is shown below
LK2ter2 1:4, 9:10
AJ5ter2 5:6
AY9ter2 7, 19
YY49ter2 10:11
al-1Tter2 12:15
CY-Yter2 16:18

Answer 1

Another option using data.table
library(data.table)
DT <- as.data.table(df)
DT[, .(index = paste(unique(range(.I)), collapse = ":")), by = .(x, rleid(x))
][, .(index = toString(index)), by = x]
# x index
#1: LK2ter2 1:4, 8:9
#2: AJ5ter2 5:6
#3: AY9ter2 7, 19
#4: YY49ter2 10:11
#5: al-1Tter2 12:15
#6: CY-Yter2 16:18

Answer 2

Using tidyverse and data.table you can do:
df %>%
rowid_to_column() %>%
group_by(x, rleid(x)) %>%
summarise(res = ifelse(min(rowid) != max(rowid),
paste(min(rowid), max(rowid), sep = ":"), paste(rowid))) %>%
group_by(x) %>%
summarise(res = paste(res, collapse = ", "))
x res
<fct> <chr>
1 AJ5ter2 5:6
2 al-1Tter2 12:15
3 AY9ter2 7, 19
4 CY-Yter2 16:18
5 LK2ter2 1:4, 8:9
6 YY49ter2 10:11
Or the same with just tidyverse:
df %>%
rowid_to_column() %>%
group_by(x, x_rleid = {x_rleid = rle(as.numeric(x)); rep(seq_along(x_rleid$lengths), x_rleid$lengths)}) %>%
summarise(res = ifelse(min(rowid) != max(rowid),
paste(min(rowid), max(rowid), sep = ":"), paste(rowid))) %>%
group_by(x) %>%
summarise(res = paste(res, collapse = ", "))
Both codes, first, add a column with row ID. Second, they group by "x" and the run-length group ID of "x". Third, they assess whether the minimum row ID is equal to maximum row ID. If not, they combine the value of minimum and maximum row ID, separated by :, otherwise use just a single row ID value. Finally, they group by just "x" and combines the different elements by ,.
Or if you want all the values, not just the ranges:
df %>%
rowid_to_column() %>%
group_by(x, x_rleid = {x_rleid = rle(as.numeric(x)); rep(seq_along(x_rleid$lengths), x_rleid$lengths)}) %>%
summarise(res = paste(rowid, collapse = ",")) %>%
group_by(x) %>%
summarise(res = paste(res, collapse = ","))
x res
<fct> <chr>
1 AJ5ter2 5,6
2 al-1Tter2 12,13,14,15
3 AY9ter2 7,19
4 CY-Yter2 16,17,18
5 LK2ter2 1,2,3,4,8,9
6 YY49ter2 10,11

Answer 3

Here's one way with dplyr methods. Not sure if you want text output or a numeric vector
library(tidyverse)
df <- structure(list(x = structure(c(5L, 5L, 5L, 5L, 1L, 1L, 3L, 5L, 5L, 6L, 6L, 2L, 2L, 2L, 2L, 4L, 4L, 4L, 3L), .Label = c("AJ5ter2", "al-1Tter2", "AY9ter2", "CY-Yter2", "LK2ter2", "YY49ter2"), class = "factor")), class = "data.frame", row.names = c(NA, -19L))
df %>%
mutate(row_number = row_number()) %>%
group_by(x) %>%
summarise(row_nums = str_c(row_number, collapse = ","))
#> # A tibble: 6 x 2
#> x row_nums
#> <fct> <chr>
#> 1 AJ5ter2 5,6
#> 2 al-1Tter2 12,13,14,15
#> 3 AY9ter2 7,19
#> 4 CY-Yter2 16,17,18
#> 5 LK2ter2 1,2,3,4,8,9
#> 6 YY49ter2 10,11
Created on 2019-02-19 by the reprex package (v0.2.1)

Answer 4

You could try something like:
z <- sapply(levels(df$x), function(x) which(x == df$x))
data.frame(key = names(z), index = sapply(z, paste, collapse = ", "), row.names = NULL)
key index
1 AJ5ter2 5, 6
2 al-1Tter2 12, 13, 14, 15
3 AY9ter2 7, 19
4 CY-Yter2 16, 17, 18
5 LK2ter2 1, 2, 3, 4, 8, 9
6 YY49ter2 10, 11