# benford_law_example.R
# accompanying lecture notes for KFoster class ECO B2000 in fall 2015 at CCNY

rm(list = ls(all = TRUE))
setwd("C:\\Users\\Kevin\\Documents\\R") # change as appropriate

library(quantmod)
getSymbols(c('GDP','PCEC','GPDI','GCE','NETEXP','CPIAUCSL','DFF'),src='FRED')
# downloads GDP then C, I, G & NX data from FRED StLouisFed data



brk_digits <- c(0,1,2,3,4,5,6,7,8,9) # just because the 0:9 notation isnt as transparent

uCPI <- 1000*CPIAUCSL # since each entry has 3 trailing digits
uFF <- 100*DFF # each has 2 trailing digits

first_digit_CPI <- as.numeric(substr(uCPI,1,1))
first_digit_FF <- as.numeric(substr(uFF,1,1))

d1_CPI <- hist(first_digit_CPI,breaks=brk_digits,plot="False")
# use $density
d1_FF <- hist(first_digit_FF,breaks=brk_digits,plot="False")

sec_digit_CPI <- as.numeric(substr(uCPI,2,2))
sec_digit_FF <- as.numeric(substr(uFF,2,2))

d2_CPI <- hist(sec_digit_CPI,breaks=brk_digits,plot="False")
d2_FF <- hist(sec_digit_FF,breaks=brk_digits,plot="False")

library(ggplot2)
qplot(brk_digits[2:10],d2_CPI$density)
qplot(brk_digits[2:10],d2_FF$density)