Cleaning of a database

[Inuraghe]

Hi everybody!

I have a problem with the cleaning of a database. What I want is to keep only the rows where in column B the word starts with "b". My actual code is:

library(dplyr)

db_class <- data.frame(A=c(2,3,3,2,1),B=c("ax","ac","bs","br","cv"),C=c(14,15,17,12,14))

row_numbers <- c(db_class %>% rowwise() %>% mutate(Pos = which((db_class$B) == starts_with("b")[1]))
db_class_clean <- db_class[row_numbers,]

I tried to write this code but it doesn't work..

[nirgrahamuk]

library(dplyr)

(db_class <- data.frame(A=c(2,3,3,2,1),
                       B=c("ax","ac","bs","br","cv"),
                       C=c(14,15,17,12,14)))

(db_class_clean <- db_class %>% 
    filter(startsWith(B,"b")))

you may benefit from studying this useful book. (it covers the use of dplyr::filter and many other useful manipulations)
https://r4ds.had.co.nz/