Select Rows with Partial String Match in R DataFrame

In this article, we’ll discuss how to select rows with a partial string match in the R programming language.

Method 1: Using stringr package

The stringr package in R language is used mainly for character manipulations, locale-sensitive operations, altering whitespace, and Pattern-matching. Here we will use its pattern matching functionality to filter data according to partial string match.

Syntax:

df[str_detect(df$column-name, "Pattern"), ]

Parameters:

• df: determines the dataframe that is being used.
• column-name: determines the column in which strings have to be filtered.
• Pattern: determines the string pattern that has to be matched.

Example: This example explains how to extract rows with a partial match using the stringr package. 

# Load library stringr
library("stringr") 

# sample dataframe
data<- data.frame(names=c('Hello','this','Hell','Geeks',
                          'Geek', 'Geeksforgeeks'))                  

# Filter data with str_detect for strings 
# containing "Gee"
result1<-data[str_detect(data$name, "Gee"), ]

# print result data
result1

# Filter data with str_detect for strings
# containing "Hel"
result2<-data[str_detect(data$name, "Hel"), ]

# print result data
result2

Output: 

[1] "Geeks"         "Geek"          "Geeksforgeeks"

[1] "Hello" "Hell" 

Method 2: Using data.table package

Data.table is an extension of data.frame package in R. It is widely used for fast aggregation of large datasets, low latency add/update/remove of columns, quicker ordered joins, and a fast file reader. Here we will use its data update of the column functionality to filter data according to partial string match. We will use %like%-operator to select the string match data and will filter data from the dataframe accordingly. 

Syntax:

df[df$column-name %like% "Pattern", ]

Parameter:

• df: determines the dataframe that is being used.
• column-name: determines the column in which strings have to be filtered.
• Pattern: determines the string pattern that has to be matched.

Example: This example explains how to extract rows with a partial match using the data.table package.  

# load data.table package
library("data.table")   

# sample dataframe
data<- data.frame(names=c('Hello','this','Hell','Geeks',
                          'Geek', 'Geeksforgeeks'))

# Filter data with %like% all strings having "Gee"
result1<-data[data$name %like% "Gee", ] 

# print result data
result1

# Filter data with %like% all strings having "Hel"
result2<-data[data$name %like% "Hel", ] 

# print result data
result2

Output:

[1] "Geeks"         "Geek"          "Geeksforgeeks"

[1] "Hello" "Hell"