R sapply() Function


title: 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.

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