[R] When using require(), why do I get the error message "Error in if (!loaded) { : the condition has length > 1" ?

[Andrew Simmons]

require(), similarly to library(), does not evaluate its first argument
UNLESS you add character.only = TRUE

require( packages_i_want_to_use[1], character.only = TRUE)


On Mon, Oct 24, 2022, 12:26 Kelly Thompson <kt1572757 using gmail.com> wrote:

> # Below, when using require(), why do I get the error message "Error
> in if (!loaded) { : the condition has length > 1" ?
>
> # This is my reproducible code:
>
> #create a vector with the names of the packages I want to use
> packages_i_want_to_use <- c('base', 'this_pac_does_not_exist')
>
> # Here I get error messages:
> require( packages_i_want_to_use[1] )
> #Error in if (!loaded) { : the condition has length > 1
>
> require( packages_i_want_to_use[2] )
> #Error in if (!loaded) { : the condition has length > 1
>
> # Here I get what I expect:
> require('base')
>
> require('this_pac_does_not_exist')
> #Loading required package: this_pac_does_not_exist
> #Warning message:
> #In library(package, lib.loc = lib.loc, character.only = TRUE,
> logical.return = TRUE,  :
> #  there is no package called ‘this_pac_does_not_exist’
>
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