Question

Construct a three-column array where column 1 is rnorm(100,2,2), column 2 is rnorm(100, 4, 4) and column 3 is rnorm(100, 0, 1). Then write the r code to change this array into an array where each column has exactly mean 0 and exactly variance 1.

Answer 1

#********************R code**********************

column1 = rnorm(100,2,2)
column2 = rnorm(100, 4, 4)
column3 = rnorm(100, 0, 1)
--
array = cbind(column1, column2, column3)

data_frame = as.data.frame(array)

#this function will standardize the data (mean zero, unit variance).
scaled_data <- scale(data_frame)

print('final array having each 0 mean and 1 variance')
print(as.matrix(scaled_data))

# check that we get mean of 0 and sd of 1
print(colMeans(scaled_data)) # faster version of apply(scaled.dat, 2, mean)
#apply(scaled.dat, 2, sd)

cat('\n\nsummary containig mean of each column is\n')
#-----You can see Mean in the summary as 0 for each colum
print(summary(scaled_data))

#apply wiil find apply fun operation which is finding standard deviation sd(third argument)
#here 2 means it will find standard deviation for each column(1 means it will find sd for ech row)
cat('\n\nVairance of each column is: \n')
print(apply(scaled_data, 2, sd))

#***************Output Screenshot***************

$************Code screenshot****************

#****Please do let me know if you have any doubts or want me to modify the code *************