Get the strings before the comma with R

Question

I am a beginner with R. Now, I have a vector in a data.frame like this

city
Kirkland,
Bethesda,
Wellington,
La Jolla,
Berkeley,
Costa, Evie KW172NJ
Miami,
P         


        

Answer 1

You could use regexpr to find the position of the first comma in each element and use substr to snip them at this:

x <- c("London, UK", "Paris, France", "New York, USA")

substr(x,1,regexpr(",",x)-1)
[1] "London"   "Paris"    "New York"

Answer 2

If the this was a column in a dataframe, we can use tidyverse.

library(dplyr)
x <- c("London, UK", "Paris, France", "New York, USA")
x <- as.data.frame(x)
x %>% separate(x, c("A","B"), sep = ',')
        A       B
1   London      UK
2    Paris  France
3 New York     USA

Answer 3

Just for fun, you can use strsplit

> x <- c("London, UK", "Paris, France", "New York, USA")
> sapply(strsplit(x, ","), "[", 1)
[1] "London"   "Paris"    "New York"

Answer 4

This works as well:

x <- c("London, UK", "Paris, France", "New York, USA")

library(qdap)
beg2char(x, ",")

## > beg2char(x, ",")
## [1] "London"   "Paris"    "New York"

Answer 5

You can use gsub with a bit of regexp :

cities <- gsub("^(.*?),.*", "\\1", df$city)

This one works, too :

cities <- gsub(",.*$", "", df$city)