CODEWITHSUNDEEP
r
TokyoToo
TokyoToo

Reputation: 926

Joining data from two vector members of a list

I have these assignment instructions.

Print, on each line, each name followed by “|”, followed by the age. Create a list where members are two vectors. The first vector holds the first names. The members of the list should have the names - "first names" and "ages". Output this list in the following format.

If I'm not mistaken, three things are required for the setup. A list containing two vectors.

first_names <- c("Jim", "Frank", "Sally")
ages <- c("25", "34", "42")
list_data <- list(first_names, ages)

# Desired Output
Jim   | 25
Frank | 34
Sally | 42

I am able to accomplish this with using just two vectors but not when they are included in a list. Am I understanding the instructions correctly?

My version with only two vectors works.

first_names <- c("Jim", "Frank", "Sally")
ages <- c("25", "34", "42")

if (length(first_names) == length(ages)) {
  for (i in 1:length(first_names)) {
    print(paste(first_names[i],ages[i],sep = " | "))
  } 
} else {
  print("Error")
}

But the version with the list is where I need help. 

first_names <- c("Jim", "Frank", "Sally")
ages <- c("25", "34", "42")
list_data <- list(first_names, ages) # list

if (length(list_data[1]) == length(list_data[2])) {
  for (i in 1:length(list_data[1])) {
    print(paste(list_data[1][i],list_data[2][i],sep = " | "))
  } 
} else {
  print("Error")
}

Upvotes: 1

Views: 59

Answers (4)

GKi
GKi

Reputation: 39647

You can use mapply with paste.

mapply(paste, list_data[1], list_data[2], sep = " | ")
#     [,1]        
#[1,] "Jim | 25"  
#[2,] "Frank | 34"
#[3,] "Sally | 42"

Or without lines and cols using writeLines:

writeLines(mapply(paste, list_data[1], list_data[2], sep = " | "))
#writeLines(paste(list_data[[1]], list_data[[2]], sep = " | ")) #Alternative
#Jim | 25
#Frank | 34
#Sally | 42

Or with your code adapted using [[ instead of [:

if (length(list_data[1]) == length(list_data[2])) {
  for (i in 1:length(list_data[[1]])) {
    writeLines(paste(list_data[[1]][i],list_data[[2]][i],sep = " | "))
  } 
} else {
  print("Error")
}
#Jim | 25
#Frank | 34
#Sally | 42

Or using sprintf to reproduce the desired ouptup:

writeLines(sprintf(paste0("%-", max(nchar(list_data[[1]])), "s", " | %s"),
 list_data[[1]], list_data[[2]]))
Jim   | 25
Frank | 34
Sally | 42

Upvotes: 1

Ronak Shah
Ronak Shah

Reputation: 388817

paste is vectorized you don't need for loop here. 

cat(paste(first_names, ages, sep = " | ", collapse = '\n'))

#Jim | 25
#Frank | 34
#Sally | 42

If you want to use these tables in some reports there are better ways available with kable or similar packages.

If we want to use list_data we can do : 

cat(paste(list_data[[1]], list_data[[2]], sep = " | ", collapse = '\n'))

Upvotes: 1

Wimpel
Wimpel

Reputation: 27732

library( data.table )
lapply( data.table::transpose(list_data), paste0, collapse = "|" )


[[1]]
[1] "Jim|25"

[[2]]
[1] "Frank|34"

[[3]]
[1] "Sally|42"

Upvotes: 1

Mukesh Kumar Singh
Mukesh Kumar Singh

Reputation: 653

Well , you can use inbuilt function paste or paste0 in R. Nothing else required

paste0(first_names,"|",ages)

The above code will print you the desired result.

To store it in a list , you can use 

as.list(paste0(first_names,"|",ages))

Upvotes: 0

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