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

Kelly Thompson kt1572757 @end|ng |rom gm@||@com
Mon Oct 24 18:42:19 CEST 2022


Thanks!

# Please, can you help me understand why
require( 'base' ) # works, but
require( packages_i_want_to_use[1] ) # does not work?

# In require( 'base' ), what is the "first argument"?

On Mon, Oct 24, 2022 at 12:29 PM Andrew Simmons <akwsimmo using gmail.com> wrote:
>
> 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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