CODEWITHSUNDEEP
rmatrixtext-mining
David T
David T

Reputation: 2143

Character-Matrix - how to operate by row?

I have a matrix of character data

charMatrix <- structure(c("Bolt", "Nut Plate", "Magnet", "", "Clevis", "welded", 
     "", "Receptacle"), .Dim = c(4L, 2L))

[,1]            [,2]        
[1,] "Bolt"      "Clevis"    
[2,] "Nut Plate" "welded"    
[3,] "Magnet"    ""          
[4,] ""          "Receptacle"

I want to paste the rows together and trim them to get the vector.

[1] "Bolt Clevis" "Nut Plate welded" "Magnet" "Receptacle"

I solved it this way, but I think there must be something much simpler, either in Base R or Tidyverse.

vec <- charMatrix %>% t() %>% 
  as_tibble(.name_repair = "universal") %>% 
  summarise_all(~ str_trim(paste(., collapse = " "))) %>% 
  unlist() %>% 
  as.character()

vec
[1] "Bolt Clevis"      "Nut Plate welded" "Magnet"           "Receptacle"

Can you show me a more direct way to get this answer?

Upvotes: 2

Views: 55

Answers (3)

Pablo C&#225;novas
Pablo C&#225;novas

Reputation: 181

You can do it easily with tidyverse:

library(tidyverse)

charMatrix %>% 
  as_tibble() %>%
  unite("Var", sep = " ") %>% 
  mutate(Var = str_trim(Var)) %>% 
  pull()

Upvotes: 0

akrun
akrun

Reputation: 887391

We can use base R by converting the matrix to data.frame and use paste with do.call

trimws(do.call(paste, as.data.frame(charMatrix)))
#[1] "Bolt Clevis"      "Nut Plate welded" "Magnet"           "Receptacle"

The do.call is vectorized and would be fast compared to looping.

Or using simple subsetting and paste

trimws(paste(charMatrix[,1], charMatrix[,2]))

Both are vectorized. The OP's question is to apply the function directly. Both of the solutions does that.

Upvotes: 2

Ronak Shah
Ronak Shah

Reputation: 389065

Since you have a matrix you can use rowwise apply and trimws to remove leading/trailing whitespaces 

trimws(apply(charMatrix, 1, paste, collapse = ' '))
#[1] "BoltClevis"      "Nut Platewelded" "Magnet"          "Receptacle"

Or remove empty values and paste. 

apply(charMatrix, 1, function(x) paste(x[x!=''], collapse = ' '))

Upvotes: 1

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