#!/bin/sh
# nightly_means_stdev
# RTH ??/??/06?  
#  Batch processes all the photometry output, and calculates std. dev. since the
#    ghetto photometry program I was using didn't do it for me.  Also does the 
#    nightly means
# RTH 11/01/07 Version 2
#  I'm trapped in the office and redoing it as a real world useful example

# Reads in original comma separated data, output from photometry reductions
datadir="./Orig_data"
for i in `ls $datadir/2005_*I*`   # Builds our list of input files
do
	# A note on regular expressions - they frequently look like you have 
	# crazy ninja-like abilities because of all the slashes, but they can be 
	# broken down.  Take this one for example: sed 's/.*\///g'`
	# sed 's/.*\///g' == sed 's/ .*\/ //g
	#      Substitute  
	# .  == match ANY character
	# *  == zero or more of the preceding thing, even wildcards (such as .)
	# \/ == backslash "deactivates" characters, interpreting them literally
	#       must be done because we use the forward slash to separate things
	# // == replace the previous thing with nothing
	# g  == do it "globally" for every occurance sed finds
	# In the final sed statement, /_//2 is used to delete 2nd occurance of _
	outp=`echo $i | sed 's/.*\///g'`
	echo "        Original    = $i"
	echo "sed 's/.*\///g'     = $outp"
	outp=`echo $outp | sed 's/.csv/.dat/g'`
	echo "sed 's/.csv/.dat/g' = $outp"
	outp=`echo $outp | sed 's/_//2'`
	echo "sed 's/_//2'        = $outp"
	awk 'BEGIN {FS=","} {if(NR!=1) print $1-2450000,$2}' $i > $outp
done

# Remove vestigial files from previous runs, if they exist. 
#   This is a low-down cheap hack because I'm lazy, and forget the 
#   switch for 'test' and I hate error messages in my output.
echo "Laziness is next to Godliness" > G_means.txt
rm ?_means.txt

# Please don't yell at me or tell Jon I'm averaging these data like this, 
# I know I should average each 3 measurements in a set & get stddev, then 
# add the errors properly.  But its an example!
for j in `ls *_I*.dat`
do
	# NR is Number of Records, i.e. how many lines were read in.
	# Again note that you basically write C code inside of {}, which is nice
	awk '{	jdtot+=$1;
		magtot+=$2;
		sqsum+=$2^2; }
	     END { jdavg = jdtot/NR; 
		   magavg=magtot/NR; 
		   sumsq=magtot*magtot; 
		   W=sumsq/NR; 
		   Q=(sqsum-W)/(NR-1); 
		   stddev=sqrt(Q); 
		   printf("%f %f %f\n",jdavg,magavg,stddev);
	     }' $j >> I_means.txt
	# >> appends to a file, creating it if it doesn't exist.  If we didn't
	# delete ?_means.txt at the beginning, the file would get messy quick.
done