Table of Contents
Collapsing text by group in a data frame is the process of combining the text from multiple rows from the same group or category into a single row. This is done by using a function such as groupby in pandas to group the data by a certain category, and then using a function such as sum or count to collapse the text for each group into a single row. This is useful for summarizing data in a data frame and reducing the amount of data displayed.
You can use the following methods to collapse text by group in a data frame in R:
Method 1: Collapse Text by Group Using Base R
aggregate(text_var ~ group_var, data=df, FUN=paste, collapse='')
Method 2: Collapse Text by Group Using dplyr
library(dplyr)
df %>%
group_by(group_var) %>%
summarise(text=paste(text_var, collapse=''))
Method 3: Collapse Text by Group Using data.table
library(data.table) dt <- as.data.table(df) dt[, list(text_var=paste(text_var, collapse='')), by=group_var]
This tutorial explains how to use each method in practice with the following data frame:
#create data frame
df <- data.frame(team=c('A', 'A', 'A', 'B', 'B', 'B'),
position=c('Guard', 'Guard', 'Forward',
'Guard', 'Forward', 'Center'))
#view data frame
df
team position
1 A Guard
2 A Guard
3 A Forward
4 B Guard
5 B Forward
6 B Center
Example 1: Collapse Text by Group Using Base R
The following code shows how to collapse the text in the position column, grouped by the team column using the aggregate() function from base R:
#collapse position values by team
aggregate(position ~ team, data=df, FUN=paste, collapse='')
team position
1 A GuardGuardForward
2 B GuardForwardCenter
Notice that each of the text values in the position column has been collapsed into one value, grouped by the values in the team column.
Example 2: Collapse Text by Group Using dplyr
The following code shows how to collapse the text in the position column, grouped by the team column using the summarise() function from the dplyr package:
library(dplyr) #collapse position values by team df %>% group_by(group_var) %>% summarise(text=paste(text_var, collapse='')) # A tibble: 2 x 2 team text 1 A GuardGuardForward 2 B GuardForwardCenter
Notice that each of the text values in the position column has been collapsed into one value, grouped by the values in the team column.
Example 3: Collapse Text by Group Using data.table
The following code shows how to collapse the text in the position column, grouped by the team column using functions from the data.table package:
library(data.table) #convert data frame to data table dt <- as.data.table(df) #collapse position values by team dt[, list(text_var=paste(text_var, collapse='')), by=group_var] team position 1: A GuardGuardForward 2: B GuardForwardCenter
Each of the text values in the position column has been collapsed into one value, grouped by the values in the team column.
The following tutorials explain how to perform other common tasks in R: