How to repeat several similar named variables in lavaan model syntax easily?-CodePudding

Suppose we have a data frame like the one below. The numbers are irrelevant to my actual query, so I have simply given them the same value.

df <- data.frame(ABC_1 = c(1,2,3),
                 ABC_2 = c(1,2,3),
                 ABC_3 = c(1,2,3),
                 ABC_4 = c(1,2,3),
                 ABC_5 = c(1,2,3),
                 ABC_6 = c(1,2,3),
                 ABC_7 = c(1,2,3),
                 ABC_8 = c(1,2,3),
                 ABC_9 = c(1,2,3),
                 ABC_10 = c(1,2,3),
                 ABC_11 = c(1,2,3),
                 ABC_12 = c(1,2,3),
                 ABC_13 = c(1,2,3),
                 ABC_14 = c(1,2,3),
                 ABC_15 = c(1,2,3),
                 ABC_16 = c(1,2,3),
                 ABC_17 = c(1,2,3),
                 ABC_18 = c(1,2,3),
                 ABC_19 = c(1,2,3),
                 ABC_20 = c(1,2,3))

Often it is the case that when one has to run a model in lavaan, they have to fit several variables into the model syntax with similar names, such as below:

mod.abc <- '
ABC_Variable =~ ABC_01   ABC_02   ABC_03   ABC_04   ABC_05  
ABC_06   ABC_07   ABC_08   ABC_09   ABC_10  
ABC_11   ABC_12   ABC_13   ABC_14   ABC_15  
ABC_16   ABC_17   ABC_18   ABC_19   ABC_20 
'

To generate repeating text sequences in R, one can do this easily with a function like this:

rep("ABC",20)

Which gives us a sequence of ABC's:

 [1] "ABC" "ABC" "ABC" "ABC" "ABC" "ABC" "ABC" "ABC" "ABC" "ABC" "ABC"
[12] "ABC" "ABC" "ABC" "ABC" "ABC" "ABC" "ABC" "ABC" "ABC"

However, copying and pasting these into the lavaan model syntax is still time consuming since one has to delete all the quotation marks. Is there a possibly easier way that doesn't require manually writing in the variables?

CodePudding user response：

You can use:

paste("ABC_variable =~", paste(names(df), collapse = "   "))

[1] "ABC_variable =~ ABC_1   ABC_2   ABC_3   ABC_4   ABC_5   ABC_6   ABC_7   
ABC_8   ABC_9   ABC_10   ABC_11   ABC_12   ABC_13   ABC_14   ABC_15   ABC_16   
ABC_17   ABC_18   ABC_19   ABC_20"

Or if I'm building more complex models, I prefer sprintf() which offers more flexibility and readability over multiple nested calls of paste().

sprintf("ABC_variable =~ %s", paste(names(df), collapse = "   "))