miceadds (version 2.2-0)

ma.scale2: Standardization of a Matrix

Description

This function performs a z-standardization for a numeric matrix. Note that in a case of a zero standard deviation all matrix entries are divided by a small number such that no NaNs occur.

Usage

ma.scale2(x, missings=FALSE)

Arguments

x

A numeric matrix in which missing values are permitted

missings

A logical indicating whether missings occur (or could occur) in the dataset

Value

A matrix

See Also

base::scale

Examples

#############################################################################
# EXAMPLE 1: z-standardization data.internet
#############################################################################

data(data.internet)
dat <- data.internet

# z-standardize all variables in this dataset
zdat <- ma.scale2( dat , missings=TRUE )
	
## Not run: 
# #############################################################################
# # SIMULATED EXAMPLE 2: Speed comparison for many cases and many variables
# #############################################################################
# 
# set.seed(9786)
# # 3000 cases, 200 variables
# N <- 3000
# p <- 200
# # simulate some data
# x <- matrix( stats::rnorm( N*p ) , N , p )
# x <- round( x , 2 )
# 
# # compare computation times for 10 replications
# B <- 10
#     s1 <- Sys.time()		# scale in R
# for (bb in 1:B){    
#     res <- scale(x)
# } ; s2 <- Sys.time() ; d1 <- s2-s1
# 
#     s1 <- Sys.time()		# scale in miceadds
# for (bb in 1:B){    
#     res1 <- ma.scale2(x)
# } ; s2 <- Sys.time() ; d2 <- s2-s1
# 
# # scale in miceadds with missing handling
#     s1 <- Sys.time()
# for (bb in 1:B){    
#     res1 <- ma.scale2(x,missings=TRUE)
# } ; s2 <- Sys.time() ; d3 <- s2-s1
# d1      # scale in R
# d2      # scale in miceadds (no missing handling)
# d3      # scale in miceadds (with missing handling)
#   ##   > d1      # scale in R
#   ##   Time difference of 1.622431 secs
#   ##   > d2      # scale in miceadds (no missing handling)
#   ##   Time difference of 0.156003 secs
#   ##   > d3      # scale in miceadds (with missing handling)
#   ##   Time difference of 0.2028039 secs
# ## End(Not run)