(Named) Lists & character vectors

During the last years, I heavily rely on using (named) lists and/or character vectors. What is a character or a character vector? A character is a string It is created using single quotes or double quotes.

myChr <- "Hi I am string"

It is possible to combine (c(...)) multiple characters into a vector or a list.

myChr1 <- "Hi I am string"
myChr2 <- "Hi I am string, too"

myChr <- c(myChr1, myChr2)

(Named) Lists

What is a list in R? Lists are objects which contain any type of other R objects (e.g., characters, numeric inputs).

myList <- list(myChr,
               "Hi Iam another string",
               3)

Sometimes¹ it is advisable to name the list elements.

myNamedList <- list(MyChr = myChr,
                    String3 = "Hi Iam another string",
                    "Number 3" = 3)

names(myNamedList) <- c("MyChr", "String3", "Number 3")

Or alternatively.

names(myList) <- c("MyChr", "String3", "Number 3")

Creating character vectors

The paste and paste0 functions are extremely powerful functions. They convert R objects to character vectors. With the sep= and collapse= arguments, it is possible to select specific character strings which separates/collapse the objects. It is important to note that the functions behave slightly different (see here). The focus here is on paste0 which sets sep="".

myName <- "John Doe"

paste0(c("hello, my name is ", myName), collapse = " <3 ")

[1] “hello, my name is <3 John Doe”

We can use the paste0 function to create the names of the variables (of a measure)². The variable names should follow a precise structure³ see Table 1.

Table 1: Overview of the Structure of Variable Names

Abbreviation of measure	Item Number	Measurement occasion
Self-concept > sc	1	T1
Self-concept > sc	2	T1
Self-concept > sc	3	T1
Self-concept > sc	1	T2
Self-concept > sc	2	T2
…	…	…

paste0 function

list("ScT1" = paste0("sc", 1:3, "T1"),
     "ScT2" = paste0("sc", 1:3, "T2"))

$ScT1
[1] "sc1T1" "sc2T1" "sc3T1"

$ScT2
[1] "sc1T2" "sc2T2" "sc3T2"

If you are really laze you could also write.

paste0("sc", 1:3, rep(paste0("T", 1:2), each = 3))

[1] "sc1T1" "sc2T1" "sc3T1" "sc1T2" "sc2T2" "sc3T2"

Footnotes

1. It is especially advisable when you want to automate table or plot generation see e.g., here

2. It is important to point out, that it might be reasonable to import the codebook instead of creating the variable names by yourself

3. On how to create codebooks see e.g. DataWiz Knowledge Base.