Strings

When working with education data, the following are a few examples of why you may need to edit strings in variables:

1. A string has purposefully been inserted into a variable but you want to remove it (ex: $ in salary)
2. A string has accidentally been inserted into a variable (ex: spaces in a numeric variable) and you need to remove them
3. A string has been used but you want to replace it with a better string (ex: school name is spelled wrong and you want to replace it with the correct spelling)
4. Strings need to be combined (ex: a prefix needs to be added variable names)

Regular expressions (regex) are a huge part of matching patterns when working with strings. It is important to get familiar with regex language: https://stat.ethz.ch/R-manual/R-devel/library/base/html/regex.html

Here is a helpful regular expression editor: https://rubular.com/

Truncate strings

• Truncate strings

Remove values strings

• Remove spaces from strings
• Remove values from strings

Replace values in strings

• Replace strings
• [Replace strings in variable names](See Name Variables)

Combine strings

• Combine strings in long data
• Combine strings in wide data
• [Combine strings in variable names](See Name Variables)

Locate strings

• [Detect patterns in strings](See several examples throughout Filter and Recode)

Split strings

• [Split strings](See Separate)

Count strings

• Count strings
• [Sum row occurrences of strings](See Calculate Row Values)

Extract values in strings

• Extract values by location
• Extract values by pattern
• Extract and combine values

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Main functions used in examples

Package	Functions
stringr	str_remove(); str_c(); str_count(); str_length(); str_sub(); str_extract(); str_trim(); str_squish(); str_detect(); str_replace(); str_trunc()
tidyr	extract()
readr	parse_number()

Other functions used in examples

Package	Functions
stringr	str_to_lower()
dplyr	mutate(); across(); group_by(); summarize()
tidyr	pivot_wider(), unite()
base	paste(); paste0(); basename(); list2env(); ls(); nchar(); max(); lapply()
janitor	tabyl()
fs	dir_ls()
here	here()
purrr	set_names()

Resources

• https://cran.r-project.org/web/packages/stringr/vignettes/regular-expressions.html
• http://edrub.in/CheatSheets/cheatSheetStringr.pdf
• https://luisdva.github.io/RLadiesSTLregex/#/title-slide
• https://stackoverflow.com/questions/68978199/if-any-string-values-in-a-character-vector-are-in-a-column-of-a-data-frame-retu