在 R 编程中查找匹配模式在字符串中的位置 – grep()函数

R 语言中的grep()函数用于在给定字符串的每个元素中搜索模式的匹配项。

Syntax: 
grep(pattern, x, ignore.case=TRUE/FALSE, value=TRUE/FALSE)
Parameters: 
pattern: Specified pattern which is going to be matched with given elements of the string. 
x: Specified string vector. 
ignore.case: If its value is TRUE, it ignores case. 
value: If its value is TRUE, it return the matching elements vector, else return the indices vector. 
 

示例 1：

Python3

# R program to illustrate
# grep function
 
# Creating string vector
x <- c("GFG", "gfg", "Geeks", "GEEKS")
 
# Calling grep() function
grep("gfg", x)
grep("Geeks", x)
grep("gfg", x, ignore.case = FALSE)
grep("Geeks", x, ignore.case = TRUE)

输出 ：

[1] 2
[1] 3
[1] 2
[1] 3 4

示例 2：

Python3

# R program to illustrate
# grep function
 
# Creating string vector
x <- c("GFG", "gfg", "Geeks", "GEEKS")
 
# Calling grep() function
grep("gfg", x, ignore.case = TRUE, value = TRUE)
grep("G", x, ignore.case = TRUE, value = TRUE)
grep("Geeks", x, ignore.case = FALSE, value = FALSE)
grep("GEEKS", x, ignore.case = FALSE, value = FALSE)          

输出：

[1] "GFG" "gfg"
[1] "GFG"   "gfg"   "Geeks" "GEEKS"
[1] 3
[1] 4