1.6 KiB
1.6 KiB
title
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| sapply() Function |
sapply() Function
The sapply() function is part of a family of apply() functions that aide in manipulating data. It takes 2 or more parameters and it returns a vector or matrix. The first parameter could be a vector or a data frame. The second parameter is usually a function you want to use along the elements of columns of the first parameter.
You can use sapply to get the max of every column in a data frame as a vector.
df <- data.frame(a = c(49, 12, 32, 21, 16), b = c(22, 39, 8, 54, 26))
df
# a b
# 1 49 22
# 2 13 39
# 3 32 8
# 4 21 54
# 5 16 26
df <- sapply(df, max)
df
# a b
# 49 54
In the above example, the data frame itself is transformed by using sapply() on it directly.
You can also use sapply() within a function.
df <- data.frame(a = c(49, 12, 32, 21, 16), b = c(22, 39, 8, 54, 26))
df
# a b
# 1 49 22
# 2 13 39
# 3 32 8
# 4 21 54
# 5 16 26
# Function to get the max number of every column for any dataframe
colMax <- function(data) sapply(data, max)
# maxes is a vector with the max number of every column in data frame df
maxes <- colMax(df)
maxes
# a b
# 49 54
You can use various different built in R functions such as sqrt, min, or mean with sapply() function.