R replace string based on other string in column

Question

I have column in dataframe which has following structure in the rows.

first cycle
first cycle
shifting cycle
shifting cycle
shifting cycle
2nd cycle 
2nd cycle
2nd cycle
shifting cycle
shifting cycle
3rd cycle
3rd cycle

I want to replace all rows with first entry of shifting cycle to shifting cycle 1 and 2nd entry of shifting cycle to shifting cycle 2. Basically it a string operation which I don' how to do it. Right I am doing it based on the value in other column but it is not appropriate to find the value in other column manually since value varies in many files.

My code

df$column <-str_replace(df$column, "Shifting cycle", "Shifting cycle 2")
df <- df %>% mutate(column = case_when(other_column ==30~ 'Shifting cycle 1' ,T~column))

so final output will be

first cycle
first cycle
shifting cycle 1
shifting cycle 1
shifting cycle 1
2nd cycle
2nd cycle 
2nd cycle
shifting cycle 2
shifting cycle 2
3rd cycle
3rd cycle

I have updated the question. Actually the shifting cycle rows were more than 1. — شاه نواز
– شاه نواز, Commented Jan 30, 2023 at 16:05
I have found the solution here it is df |> dplyr::mutate( x = ifelse( x == "shifting cycle", paste(x, cumsum(x == "shifting cycle" & dplyr::lag(x,default = "") != "shifting cycle")), x)). Thanks to R4DS community on slack. X is the column with existing data. — شاه نواز
– شاه نواز, Commented Jan 30, 2023 at 17:22

margusl · Accepted Answer · 2023-01-30 17:23:16Z

Run Length Encoding to detect runs, generate a sequence to match number of rows in the dataframe and pass it through integer division by 2
(1 1 2 2 2 3 3 3 4 4 5 5 becomes 0 0 1 1 1 1 1 1 2 2 2 2 ).

The very first run will be coded as 0, to deal with those cases where dataset starts with a shifting cycle , we'll add + sc_runs$values[1], this avoids shifting cycle 0

library(dplyr)
sc_str <- "shifting cycle"

sc_runs <- rle(df2$column == sc_str)
sc_runs
#> Run Length Encoding
#>   lengths: int [1:5] 2 3 3 2 2
#>   values : logi [1:5] FALSE TRUE FALSE TRUE FALSE

sc <- rep(seq_along(sc_runs$lengths), sc_runs$lengths) %/% 2 + sc_runs$values[1]
sc
#>  [1] 0 0 1 1 1 1 1 1 2 2 2 2

df2 %>%
  mutate(
    column =
      case_when(
        column == sc_str ~ paste(column, sc),
        TRUE ~ column
      )
  )
#> # A tibble: 12 × 1
#>    column          
#>    <chr>           
#>  1 first.cycle     
#>  2 first cycle     
#>  3 shifting cycle 1
#>  4 shifting cycle 1
#>  5 shifting cycle 1
#>  6 2nd cycle       
#>  7 2nd cycle       
#>  8 2nd cycle       
#>  9 shifting cycle 2
#> 10 shifting cycle 2
#> 11 3rd cycle       
#> 12 3rd cycle

Input data:

df2 <- tibble::tribble(
           ~column,
     "first.cycle",
     "first cycle",
  "shifting cycle",
  "shifting cycle",
  "shifting cycle",
       "2nd cycle",
       "2nd cycle",
       "2nd cycle",
  "shifting cycle",
  "shifting cycle",
       "3rd cycle",
       "3rd cycle"
  )

df <- tibble::tribble(
           ~column,
     "first.cycle",
     "first cycle",
  "shifting cycle",
       "2nd cycle",
       "2nd cycle",
       "2nd cycle",
  "shifting cycle",
       "3rd cycle",
       "3rd cycle"
  )

# answer that was targeting the first variant of example data
df %>%
  mutate(
    column =
      case_when(
        column == "shifting cycle" ~ paste(column, cumsum(column == "shifting cycle")),
        TRUE ~ column
      )
  )

^{Created on 2023-01-30 with reprex v2.0.2}

The shifting cycle rows are many so can you change the code . Right now it is giving me unique number for each row like Shifting cycle 1, Shifting cycle 2. Sorry if my question was not much clear

HoelR · Accepted Answer · 2023-01-30 15:49:01Z

1

library(tidyverse)

df %>%
  group_by(group = str_detect(cycles, "shifting cycle")) %>%
  mutate(cycles = case_when(
    group == TRUE ~ str_c(cycles, 1:n(), sep = " "),
    TRUE ~ cycles)) %>% 
  ungroup() %>% 
  select(-group)

# A tibble: 9 × 1
  cycles          
  <chr>           
1 first cycle     
2 first cycle     
3 shifting cycle 1
4 2nd cycle       
5 2nd cycle       
6 2nd cycle       
7 shifting cycle 2
8 3rd cycle       
9 3rd cycle

answered Jan 30, 2023 at 15:49

HoelR

6,8771 gold badge8 silver badges18 bronze badges

1 Comment

شاه نواز Over a year ago

The shifting cycle rows are many so can you change the code . Right it is giving me unique number for each row like Shifting cycle 1, Shifting cycle 2. Sorry if my question was not much clear

Collectives™ on Stack Overflow

R replace string based on other string in column

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related