如何在R中使用substring函数和apply？

Question

The dataset contains information about superheroes. This code removes the annoying bracket part from the string 'name':

# package loading
library(fivethirtyeight)

# data opening
data(package ="fivethirtyeight")
data(comic_characters)

for (i in 1:length(comic_characters$name)) 
{
  bracket[i]                <-  which(strsplit(comic_characters$name[i], "")[[1]] == "(")
  comic_characters$name[i]  <-  substr(comic_characters$name[i], start = 1, stop = bracket[i]-2)
}

How can I do the same thing using apply functions (without for loop)? Here's how I tried:

     bracket = sapply(sapply(strsplit(comic_characters$name, ''), function(x) 
    which(x == '(')), `[`, 1)  

    # here comes the problem:
        comic_characters$name <- lapply(x, function(x)
 substr(comic_characters$name, start=1, stop=bracket[i]-2)) 

How can I do this? Thank you in advance!

Answer 1

Wouldn't this achieve the same thing?

df <- data.frame(comic_characters)
df$name <- sub("\\(.*", "", df$name)

Answer 2

You could use the stringr package to achieve your goal.

# package loading
library(fivethirtyeight)
library(stringr)

# data opening
data(package ="fivethirtyeight")
data(comic_characters)

# remove text enclosed in brackets from character names
cleaned_character_names <- str_replace_all(
  string = comic_characters$name,
  pattern = "\\(.*\\)",
  replacement = ""
)

# trim whitespace from start and ending of the character names
cleaned_character_names <- str_trim(
  string = cleaned_character_names
)

Some of the character names have two parts that are enclosed in brackets, eg "Rogue (Anna Marie) (Earth-616)". The code above will remove both "(Anna Marie)" and "(Earth-616)" from the character name.