Let the input file where you have the data be called input.txt.
We will call the first column containing the marker information x and the second column containing the test statistic y. This file can include in its top row the characters x y. This is called a header. The choice is up to the user to put the header in or not.
For entering R on the Linux machine on prompt type:
R
Once you are in R the steps for using BARS are as follows:
1) Load the shared object library:
dyn.load("barsN.so",now = F)
2) Source the R wrapper file:
source("barsN_R_wrapper")
3) Read in the data file,input.txt:
With header:
l = read.table("input.txt",header = T)
attach(l)
Without header:
l = read.table("input.txt")
x = l[,1]
y = l[,2]
4) Run BARS
out = barsN.fun(x,y)
5) To view all of the BARS results (NOTE: the output may be quite lengthy, so you may want to access particular portions of the output using the $ operator - see below.):
out
There are certain other commands which we can use for viewing the results:
1) To plot the x and y values.
plot( x ,y , xlab = 'x values', ylab = 'yvalues')
2) To fit a curve using BARS data
lines(x , out$postmodes)
3) To find the maximum height of the BARS curve
out$peakheightmode
4) To find the location of the maximum height of the BARS curve
out$peaklocationmode
5) To find the confidence interval for the peak location
out$peaklocationquantile
The BARS test is significant if this interval is a proper subset of the range defined
by min(x), max(x). to see what this interval is,
min(x)
max(x)
6) To find the distribution of the peak locations
hist(out$samplpeaks)
7) To change the level of confidence in the test to something other than 95% say 99%,
use the option "conf = 0.99" in the barsN.fun command
out = barsN.fun(x,y,conf = 0.99)
Note : Another Method to fit a curve using the smooth.spline function
lines(smooth.spline( x, y, cv = T))
To find the maximum height of the smooth.spline curve
ssout = smooth.spline( x , y , cv = T)
lm = predict(ssout)
max(lm$y)
To find more details of the parameters and options available for BARSN please
have a look at BARSN_options.