1 | initial version |
Iterating over groups in R involves the following steps:
group_by()
from the dplyr
package to group the data by a variable or set of variables.map()
from the purrr
package to apply a function to each group.bind_rows()
from the dplyr
package to combine the results of the iteration into a single dataset.For example, to calculate the mean of a variable for each group in a dataset, we can use the following code:
library(dplyr)
library(purrr)
# Load dataset
data <- iris
# Group by species
data_grouped <- data %>% group_by(Species)
# Iterate over groups and calculate mean of Petal.Length
mean_petal_length <- map(data_grouped, function(group) {
mean(group$Petal.Length)
})
# Combine results into a single dataset
result <- bind_rows(mean_petal_length, .id = "Species")
This code groups the iris
dataset by the Species
column, iterates over each group to calculate the mean of the Petal.Length
column, and combines the results into a new dataset with a Species
column and a mean
column.