Identify positions in R

Identify positions in R, we will explore how to use the str_subset and str_which functions in R to filter and find patterns in character strings.

These functions are part of the stringr package, which provides a variety of functions for working with strings.

To demonstrate the usage of str_subset and str_which, we will create a vector of character strings x and install/load the stringr package:

install.packages("stringr")
library("stringr")
x <- c("aaa", "bbb", "abc")

Example 1: Using str_subset to Filter Patterns

We can use the str_subset function to filter a character string vector and keep only the strings that match a pattern.

For example, we can use it to extract all character strings that contain the letter “a”:

str_subset(x, "a")

This will output a vector of character strings that contain the letter “a”:

# "aaa" "abc"

As you can see, str_subset has filtered our original vector and returned only the strings that match the pattern.

Example 2: Using str_which to Find Positions

We can also use the str_which function to find the positions of character strings that match a pattern.

For example, we can use it to find the positions of all character strings that contain the letter “a”:

str_which(x, "a")

This will output a vector of indices that indicate the positions of the character strings that match the pattern:

# 1 3

The RStudio console output shows that the character strings at position 1 and 3 of our vector are containing the letter “a”.

Conclusion

In this article, we have learned how to use the str_subset and str_which functions in R to filter and find patterns in character strings.

By using these functions, you can easily extract specific patterns from your data and identify their positions.