CODEWITHSUNDEEP
rstringsplit
user3697665
user3697665

Reputation: 307

How to wrap a character vector based on a specific character?

Suppose I have 

 raw = 
 [1] "r"                 "csv"               "python"           
 [4] "r"                 "r"                 "c++"              
 [7] "r"                 "matrix"            "eigen"            
[10] "r"                 "data.frame"        "r"                
[13] "subset"            "r"                 "for-loop"         
[16] "r"                 "debugging"         "matrix"           
[19] "r"                 "histogram"         "distribution"     
[22] "lattice"           "r"                 "dplyr"            
[25] "r"                 "gecode"            "r"

I want to wrap this string list based on the character r, i.e.

[1] "r; csv; python"
[2] "r"
[3] "r; c++"
[4] "r; matrix; eigen"

I used strsplit() to split by r but it doesn't work that well... any suggestions

Upvotes: 2

Views: 432

Answers (2)

bramtayl
bramtayl

Reputation: 4024

Or the dplyr method:

data_frame(raw = raw) %>%
  mutate(ID = cumsum(raw == "r") ) %>%
  group_by(ID) %>%
  summarize(result = raw %>% paste(collapse = "; ") )

Upvotes: 0

Rich Scriven
Rich Scriven

Reputation: 99361

You could split then paste. Splitting on cumsum(raw == "r") will give us the splitting index where each split begins with r. Then we can iterate over the list, pasting the values together. Since we know the result will be a single character element for each iteration, we can use vapply().

vapply(unname(split(raw, cumsum(raw == "r"))), paste, "", collapse = "; ")
# [1] "r; csv; python"                     
# [2] "r"                                  
# [3] "r; c++"                             
# [4] "r; matrix; eigen"                   
# [5] "r; data.frame"                      
# [6] "r; subset"                          
# [7] "r; for-loop"                        
# [8] "r; debugging; matrix"               
# [9] "r; histogram; distribution; lattice"
#[10] "r; dplyr"                           
#[11] "r; gecode"                          
#[12] "r"

Data:

raw <- c("r", "csv", "python", "r", "r", "c++", "r", "matrix", "eigen", 
"r", "data.frame", "r", "subset", "r", "for-loop", "r", "debugging", 
"matrix", "r", "histogram", "distribution", "lattice", "r", "dplyr", 
"r", "gecode", "r")

Upvotes: 3

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