Question

1. You are given R function below:

TestFunction <- function(df){

M <- rep(0,ncol(df)) for(i in 1:ncol(df)){ M[i] <- max(df[,i],na.rm=TRUE) }

return(M) } colMax <- function(df){

M <- rep(0,ncol(df))

for(i in 1:ncol(df)){

M[i] <- max(df[,i])

}

return(M)

}

Describe briefly what this function does

Answer 1

Explanation is given in the columns

Function - 1 :

TestFunction <- function(df){ # this function computes the dataframe df

M <- rep(0,ncol(df)) # ncol(df) will return the number of columns in the dataframe

# rep functions fills the vector with 0 of size 11 and stores the vector in M

for(i in 1:ncol(df)){ M[i] <- max(df[,i],na.rm=TRUE) }

# returns the max element in every column. A problem can occur, when your data contains # NA values (i.e. missing data). //Here the option na.rm=TRUE within the max function

# says that the NULL values are present in the column and asif it is true ignores NA and

# returns max value. If the na.rm=TRUE is not true then and if the NULL values present in

# the column then max becomes NA. If na.rm=TRUE then the max would be the maximum # number.

return(M) }

Function - 2 :

colMax <- function(df){ # this function computes the dataframe df

M <- rep(0,ncol(df))# ncol(df) will return the number of columns in the dataframe

# rep functions fills the vector with 0 of size 11 and stores the vector in M

for(i in 1:ncol(df)){

M[i] <- max(df[,i])

# returns the max element in every column. A problem can occur, when your data contains # NA values (i.e. missing data). //Here the option na.rm=TRUE within the max function

# says that the NULL values are present in the column and asif it is true ignores NA and

# returns max value. If the na.rm=TRUE is not true then and if the NULL values present in

# the column then max becomes NA. If na.rm=TRUE then the max would be the maximum # number.

}

return(M)

}