Question for mutate_at and string mismatches

[Gracezhao]

I encountered a very confusing problem. When I run this code, I cannot get its results. Prompt to:
Error in mutate_at(., vars(oac_grp, sex, age_band, age_sex), ~factor(.)) :
There is no "mutate_at" function

and also There is no "%>%" function

There is also an error about string mismatches：

Thank you so much！

[martin.R]

You need to load the relevant packages first:

library(dplyr)

[Gracezhao]

@martin.R

library(dplyr)

individuals <- individuals %>% mutate_at(vars(oac_grp, sex,age_band, age_sex),~factor(.))

I have used install.packages("dplyr"). But it reminds me that There is no "%>%" function

[nirgrahamuk]

@Gracezhao

install.packages("dplyr")

@martin.R

library(dplyr)

These are different commands.
The first one you must do once to have dplyr on your system. The second one you need once in every subsequent r session if you want to use the dplyr functionality in that session.