如何移除字符串中的第n个字符？如何通过索引删除字符串中的字符（附R语言示例）

Hey there! Let's break down your two questions with practical R solutions, since your example uses an R vector.

1. Removing the nth character from a single string #

If you need to strip out a specific position n from a string, you have a couple of reliable options:

Base R approach #

Use substr() to split the string into two parts (before the nth character, and after it), then paste them together:

# Example: Remove the 3rd character from "Hello"
my_string <- "Hello"
n <- 3
result <- paste0(substr(my_string, 1, n-1), substr(my_string, n+1, nchar(my_string)))
# Output: "Helo"

Here, substr(my_string, 1, n-1) grabs everything up to the (n-1)th character, and substr(my_string, n+1, nchar(my_string)) takes everything from the (n+1)th character to the end. Pasting them removes the nth character entirely.

Using the stringr package (tidyverse-friendly) #

If you prefer regex or the tidyverse ecosystem, str_remove() with a custom regex works great:

library(stringr)
my_string <- "Hello"
n <- 3
result <- str_remove(my_string, sprintf("^(.{%d}).", n-1))
# Output: "Helo"

The regex ^(.{n-1}). matches the first (n-1) characters, then captures the nth character with the final .—replacing this match with nothing removes the nth character.

2. Deleting every second character from strings in an R vector #

For your specific example (name <- c("Jackkk","Markkk","Jayyy")), where you want to remove every second character from each string (i.e., keep characters at positions 1, 3, 5, ...), here's how to do it efficiently:

Base R solution #

Use sapply() to loop through each string, split it into individual characters, keep only the odd-indexed characters, then rejoin them:

name <- c("Jackkk","Markkk","Jayyy")

# Remove every second character (keep positions 1,3,5...)
clean_names <- sapply(name, function(x) {
  chars <- strsplit(x, "")[[1]]  # Split string into single characters
  paste0(chars[seq(1, length(chars), 2)], collapse = "")  # Keep odd positions & rejoin
})

# Output:
#  Jackkk   Markkk    Jayyy 
#  "Jckk"   "Makk"    "Jy" 

Let's verify the results:

• "Jackkk" → J (1), c (3), k (5) → "Jckk"
• "Markkk" → M (1), r (3), k (5) → "Makk"
• "Jayyy" → J (1), y (3) → "Jy"

If you actually meant removing only the second character (not every second one) from each string, adjust the function to use the first question's logic:

clean_names_single <- sapply(name, function(x) paste0(substr(x,1,1), substr(x,3,nchar(x))))
# Output:
#  Jackkk   Markkk    Jayyy 
# "Jckkk"  "Mrkkk"   "Jyyy"

内容的提问来源于stack exchange，提问作者user19100232