在R中匹配和替换

grep(pattern, x, ignore.case = FALSE, perl = FALSE, value = FALSE, fixed = FALSE, useBytes = FALSE)

# 在字符向量中匹配包含"apple"的项
fruits <- c("apple", "banana", "orange", "grape")
matches <- grep("apple", fruits)
print(matches)  # 输出：1

# 在字符向量中匹配以"a"开头的项
matches <- grep("^a", fruits)
print(matches)  # 输出：1 2

# 在字符向量中匹配以"e"结尾的项（忽略大小写）
matches <- grep("e$", fruits, ignore.case = TRUE)
print(matches)  # 输出：1 3

gsub(pattern, replacement, x, ignore.case = FALSE, perl = FALSE, fixed = FALSE, useBytes = FALSE)

# 替换字符向量中的"apple"为"pear"
fruits <- c("apple", "banana", "orange", "grape")
replaced <- gsub("apple", "pear", fruits)
print(replaced)  # 输出：pear banana orange grape

# 替换字符向量中以"a"开头的项为"fruit"
replaced <- gsub("^a", "fruit", fruits)
print(replaced)  # 输出：fruitpple banana fruitnge grape

# 替换字符向量中以"e"结尾的项为空字符串（忽略大小写）
replaced <- gsub("e$", "", fruits, ignore.case = TRUE)
print(replaced)  # 输出：appl banana orang grap