Find Positions of Dots in Character String in R (3 Examples)
In this R tutorial you’ll learn how to locate all dots (i.e. points) in a character string.
The tutorial contains this:
Let’s dive into it!
Creation of Example Data
The following data will be used as basement for this R tutorial:
my_string <- "aaa.b.cccc.d.e" # Create example character string my_string # Print example character string #  "aaa.b.cccc.d.e"
As you can see based on the previous RStudio console output, our example data is a single character string stored in the data object my_string.
Example 1: Get All Dot Locations in Character String Using gregexpr() & unlist() Functions
Example 1 illustrates how to locate all dots in a character string.
To accomplish this, we can apply the gregexpr and unlist functions to our character string as shown below:
all_dots <- unlist(gregexpr("\.", my_string)) # Get all dot locations all_dots # Return all dot locations #  4 6 11 13
The previous output shows the index positions of all dots in our character string.
Example 2: Get Location of First Dot in Character String
In this example, I’ll explain how to extract only the very first dot position in a character string that contains multiple dots.
For this, we can use the data object all_dots that we have created in Example 1 of this tutorial:
first_dot <- all_dots # Extract first dot position first_dot # Print first dot position #  4
The first dot is located at the fourth character position in our example string.
Example 3: Get Location of Last Dot in Character String
Similar to Example 2, we can use the all_dots data object to find the last dot in a character string.
Consider the following R syntax:
last_dot <- all_dots[length(all_dots)] # Extract last dot position last_dot # Print last dot position #  13
The last dot is at the 13th position of our string.
Video & Further Resources
Have a look at the following video on my YouTube channel. I explain the contents of this tutorial in the video:
Also, you could have a look at the related tutorials on this website:
- Find Position of Character in String
- Find & Count Exact Matches in Character String Vector
- All R Programming Examples
To summarize: You have learned in this post how to find all positions of dots in a character string in R programming. Let me know in the comments, if you have further comments or questions.