dplyr filter on a vector rather than a dataframe in R

user_5573294 0
Viewed 16859

This seems like a simple question, but I have not come across a clean solution for it yet. I have a vector in R and I want to remove certain elements from the vector, however I want to avoid the vector[vector != "thiselement"] notation for a variety of reasons. In particular, here is what I am trying to do:

# this doesnt work
all_states = gsub(" ", "-", tolower(state.name)) %>% filter("alaska")

# this doesnt work either
all_states = gsub(" ", "-", tolower(state.name)) %>% filter(!= "alaska")

# this does work but i want to avoid this approach to filtering
all_states = gsub(" ", "-", tolower(state.name))
all_states = all_states[all_states != "alaska"]

can this be done in a simple manner? Thanks in advance for the help!

EDIT - the reason I'm struggling with this is because I'm only finding things online regarding filtering based on a column of a dataframe, for example:

my_df %>% filter(col != "alaska")

however I'm working with a vector not a dataframe here

dplyr r
3 Answers

Sorry for posting on a 5-month-old question to archive a simpler solution.

Package dplyr can filter character vectors in following ways:

> c("A", "B", "C", "D") %>% .[matches("[^AB]", vars=.)]
[1] "C" "D"
> c("A", "B", "C", "D") %>% .[.!="A"]
[1] "B" "C" "D"

The first approach allows you to filter with regular expression, and the second approach uses fewer words. It works because package dplyr imports package magrittr albeit masks its functions like extract, but not the placeholder ..

Details of placeholder . can be found on within help of forward-pipe operator %>%, and this placeholder has mainly three usage:

  • Using the dot for secondary purposes
  • Using lambda expressions with %>%
  • Using the dot-place holder as lhs

Here we are taking advantage of its 3rd usage.

user_7597320
Related