###################################################
# Monte-Carlo experiment
# reading example file 
# 1981-2010 monthly mean tavg anomalies
# random sampling from data 
# with varying sample siz
###################################################

# clear memory
rm(list=ls())

###################################################
# User's program control parameters
###################################################
# station
stationname<-"USW00014735"
# variable
varname<-"tavg"
# first and last year for averaging
yr1<-1981
yr2<-2010



###################################################
# Main program 
###################################################
source("scripts/myfunctions.R")
infile<-paste("data/",stationname,"_",varname,"_mon_mean_ano.csv",sep='')
buffer<-read.csv(infile)
# data are in column 2
time<-buffer[,2]
x<-buffer[,3]
inum<-length(x)

# set a sample size 
nsample<-10
# pick the first n  
# from the random index values
# returns in random order inum numbers
# in range 1 to inum
random<-sample(inum)
pick<-random[1:nsample]
print(mean(x[pick]))