What is the use of with() and by() functions in R?

The with() function applies an expression to a dataset, and the by() function applies a function to each level of factors.

In R, the with() and by() functions serve different purposes:

with() function:

The with() function is used to simplify the syntax when working with data frames or lists. It allows you to refer to the variables within a data frame directly without repeating the data frame name.
Here’s a simple example:

data <- data.frame(x = 1:5, y = c(“A”, “B”, “C”, “D”, “E”))
with(data, mean(x)) # Instead of data$mean(data$x)
by() function:

The by() function is used for applying a function to subsets of a data frame or vector, broken down by one or more factors. It is often used with the tapply() function to split data into groups and then apply a function to each group.
Here’s an example:

data <- data.frame(x = 1:10, y = c(“A”, “B”, “C”, “A”, “B”, “C”, “A”, “B”, “C”, “A”))
by(data$x, data$y, mean) # Calculates the mean of x for each level of y
In summary:

with() is used for easier access to variables within data frames or lists.
by() is used for applying a function to subsets of data based on one or more factors.