RinAction - Basic Statistics - Frequency Table

gistfile1.r

#-----------------------------------------------------------------------------#
#-----------------------------------------------------------------------------#
# R in Action - Basic Statistics
# - Frequency Table
#-----------------------------------------------------------------------------#
#-----------------------------------------------------------------------------#

install.packages(c('npmc', 'ggm', 'gmodels', 'vcd', 'Hmisc','pastecs', 'psych', 'doBy', 'reshape'))

#######################################################
#######################################################
# -------- Frequency and Contingency Table ---------- #
#######################################################
#######################################################

# get Arthritis data
library(vcd)

###################################
### 1. One-Way Tables
###################################

# one way table
mytable <- with(Arthritis, table(Improved))
mytable

prop.table(mytable)
prop.table(mytable)*100

###################################
### 2. Two-Way Tables Using Table()
###################################

# two-way frequency using table()
mytable <- with(Arthritis,table(Treatment, Improved, useNA="ifany")) # by default ignore missing
mytable

# two-way freq using xtabs()
mytable <- xtabs(~ Treatment+Improved, data=Arthritis)
mytable

# row sums and percentages
margin.table(mytable, 1)
prop.table(mytable, 1)
           
# column sums and percentages
margin.table(mytable, 2)
prop.table(mytable, 2)

# Cell Percentages
prop.table(mytable)

# Add marginal SUMs
addmargins(mytable)
addmargins(prop.table(mytable))
addmargins(prop.table(mytable, 1), 2)
addmargins(prop.table(mytable, 2), 1)

d <- as.data.frame(addmargins(mytable))


#########################################
### 2. Two-Way Tables Using CrossTable()
#########################################

# Two-way table using CrossTable (similar to SAS Proc Freq)
library(gmodels)
CrossTable(Arthritis$Treatment, Arthritis$Improved)
    
help(CrossTable)

#########################################
### 2. Multidimensional Contingency Table
#########################################

# xtabs()
mytable <- xtabs(~ Treatment+Sex+Improved, data=Arthritis)
mytable

# table()
with(Arthritis, table(Treatment,Sex,Improved))

# ftable()
ftable(mytable)
margin.table(mytable, 1)
margin.table(mytable, 2)
margin.table(mytable, 3)
margin.table(mytable, c(1,3))
ftable(prop.table(mytable, c(1, 2)))
ftable(addmargins(prop.table(mytable, c(1, 2)), 3))
           
ftable(addmargins(prop.table(mytable, c(1, 2)), 3)) * 100