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R str_replace() and str_replace_all() are used to replace values of a string column based on matched patterns ( pattern matching with regex – regular expression), also used to replace with a specific string or character value. This function can be used on both DataFrame columns and a vector.

In order to use this str_replace() method, first, you need to load its library using library("stringr"). In case you don’t have this package, install it using install.packages("stringr"). The stringr package provides a set of functions to work with strings as easily as possible. 

1. str_replace() Syntax

Following is a syntax of str_replace() method from stringr package.

# Syntax of str_replace()
str_replace(string, pattern, replacement)
str_replace_all(string, pattern, replacement)
  • string: Character vector
  • pattern: Pattern to look for
  • replacement: A character vector of replacements. It can be a replacement string.

Let’s create an R dataframe and explore some examples using str_replace() method.

# Create DataFrame
df <- data.frame(id=c(1,2,3,4),
    address=c('Orange St','Anton Blvd','Jefferson Pkwy','Main St'))

#  id        address
#1  1      Orange St
#2  2     Anton Blvd
#3  3 Jefferson Pkwy
#4  4        Main St

2. Use str_replace() to Replace Part of String with Another String

str_replace() method from stringr package is used to replace a part of a string on column with another string or replace column with pattern matching. The following example replaces string St with Street on column address. Here, df$address is a vector. Note that every column in a DataFrame is a vector.

If you wanted to replace NA with Empty String in R dataframe use methods from dplyr package.

# Replace String with anotehr String
df$address <- str_replace(df$address, "St", "Street")

Yields below output.

# Output
  id        address
1  1  Orange Street
2  2     Anton Blvd
3  3 Jefferson Pkwy
4  4    Main Street

3. str_replace_all() to Match on Multiple Strings

Use str_replace_all() method of stringr package to replace multiple string values at a time on a single column. The following example takes vector c() with mapping of values to be replaced on address column.

# Replace multiple strings at a time
rep_str = c('St'='Street','Blvd'='Boulevard','Pkwy'='Parkway')
df$address <- str_replace_all(df$address, rep_str)

Yields below output

# Output
  id           address
1  1     Orange Street
2  2   Anton Boulevard
3  3 Jefferson Parkway
4  4       Main Street

4. Replace With Pattern Matching (regex)

Since these methods are used on vector, let’s create a R vector and replace values in it with pattern matching. Since every column in a DataFrame is a vector, you can also use pattern matching on DataFrame columns.

# Create Vector
numbers <- c("one", "two", "three")
num <- str_replace(numbers, "[oe]", "-")

# Output
[1] "-ne"   "tw-"   "thr-e"

Now let’s use str_replace_all() on the same example.

# Create Vector
numbers <- c("one", "two", "three")
num2 <- str_replace_all(numbers, "[oe]", "-")

# Output
[1] "-n-"   "tw-"   "thr--"

5. Conclusion

In this article, you have learned str_replace() and str_replace_all() methods from sringr package are used to replace part of a string from a column to another string. Also, these methods are used to replace the string with another string based on pattern matching.


Naveen Nelamali

Naveen Nelamali (NNK) is a Data Engineer with 20+ years of experience in transforming data into actionable insights. Over the years, He has honed his expertise in designing, implementing, and maintaining data pipelines with frameworks like Apache Spark, PySpark, Pandas, R, Hive and Machine Learning. Naveen journey in the field of data engineering has been a continuous learning, innovation, and a strong commitment to data integrity. In this blog, he shares his experiences with the data as he come across. Follow Naveen @ LinkedIn and Medium