#!/usr/bin/perl 
# by Harry Mangalam, mangalam@home.com.

# mod 4.21.00 adding check for FLAT mode, modecount =1
# mod 11.24.99 adding Mode, Mode count, Median to output.

# This is FREEWARE, and is worth exactly that! 
# perloid to take stdin of as many #s as are in the stream, whether in one line 
# or in many lines (only have to be separated by whitespace), calculate some 
# basic stats, then spit to stdout  so that the output can be 
# grep'ped in the std unixy way..

# usage: stats < file.of.numbers
#     or
# cmd1 | cmd2 |cmd3 | stats

# eg, to calculate a summary of the bytes used in the current directory:
#
#   3 % ls -l | cut -c31-42 |stats
#
#   Sum      = 158401735            158.4 MB total
#   N        = 503                  in 503 files
#   Mean     = 314913.986083499     average size of file is 315 KB
#   Median   = 10204                median size is 10 KB
#   Mode (#) = 1024 (33)            mode is 1024 due to 33 directories
#   Min      = 0                    at least 1 empty file
#   Max      = 27135470             got a whomper of a file at 2.7 MB
#   Variance = 2903105341782.66     huge variance
#   Std Dev  = 1703850.15238508     etc
#   SEM      = 75970.9233614217
#   Skew     = 12.1873963279124
#   Std Skew = 111.588464543135

# To use from nedit, put it in your /usr/local/bin and add the following
# to your .nedit file under shell commands:
#
#        stats:::IW:\n\
#                stats\n
#
#
# Feel free to add whatever additional calclations you want, but if you do and
# you think they might be of general use, let me know so I can add them to the
# original.
# Bug reports, suggestions back to the author

$N = 0;
$sum = 0;
$Min = $Max = 0;

while (<>) {
	$x = split;
	for ($i = 0; $i < $x; $i++) {
	  	$sum = $sum + @_[$i]; # sum the numbers as they come in
      if ($N == 0) { 
         $Min = $Max = @_[$i]; 
      }
      if (@_[$i] < $Min) { $Min = @_[$i]; }
      if (@_[$i] > $Max) { $Max = @_[$i]; }
      
		$Data[$N++] = @_[$i];  # store them for calcing the SD, etc
   }
}
# All the numbers sucked in; now calc the values wanted
# if want to get mode, median, would help to sort $Data
@SData = sort numerically @Data;
#for ($i = 0; $i < $N; $i++) {
#  print "\n $i :$Data[$i] \t $SData[$i]";
#}
if ($N % 2 < 0.001) { 
# 	print " $N is even.\n";
	#then $N is even and we can calc median via...
   $Median = ($SData[($N-1)/2] + $SData[(($N-1)+2)/2]) / 2;
	$even = 1; 
} else { 
	# then $N is odd and we can calc median via...
# 	print " $N is odd.\n";
   $Median = ($SData[($N+1)/2]) ;
	$even = 0; 
}

$Mean = $sum / $N;
$SumDiffs2 = 0;
$SumDiffs3 = 0;

$MaxSoFarValCnt = 0;
$ModeInd = 0;
$ValCnt = 0;
$Val = $SData[0];

for ($i=0; $i < $N; $i++){
	$SumDiffs2 = $SumDiffs2 + (($Data[$i] - $Mean)**2);
	$SumDiffs3 = $SumDiffs3 + (($Data[$i] - $Mean)**3);

	# this next stanza calculates the Mode pointer
   if ($Val == $SData[$i]) { 
   	# if its another of the same #, incr the counters
   	$ValCnt++;
#      print "ValCnt = $ValCnt\n";
      $Val = $SData[$i];
   } else { # it's a new value, so check if the run of the last set of #s 
   			# exceeds the longest so far
#      print "$MaxSoFarValCnt =  $MaxSoFarValCnt \n";
   	if ($ValCnt > $MaxSoFarValCnt) {
      	# and if so, replace the old values with the new 'winners'
      	$MaxSoFarValCnt = $ValCnt;
         $ModeInd = $i-1;
#         print "ModeInd = $ModeInd \n";
      }  
      # and reset the counters for the new 
      $ValCnt = 0;
   }
   $Val = $SData[$i];
   
}
if ($MaxSoFarValCnt > 1) {
   $ModeNum = $MaxSoFarValCnt + 1;
   $Mode = $SData[$ModeInd];
} else {
   $ModeNum = "No # was represented more than once";
   $Mode = "FLAT";	
}
$S2 = $SumDiffs2 / ($N - 1);
$S = sqrt($S2);
$SEM = $S / sqrt($N);
print  "\nSum      = ", $sum, 
       "\nN        = ", $N, 
		 "\nMean     = ", $Mean, 
		 "\nMedian   = ", $Median, 
		 "\nMode (#) = ", $Mode, " ($ModeNum)",
       "\nMin      = ", $Min,
       "\nMax      = ", $Max,
		 "\nVariance = ", $S2, 
		 "\nStd Dev  = ",	$S, 
		 "\nSEM      = ", $SEM, "\n";
if ($S > 0 && $N > 3) {
	$Skew = ($N * $SumDiffs3) / (($N-1) * ($N-2) * ($S ** 3));
	$StdSkew = $Skew / sqrt(6/$N);
	print "Skew     = ", $Skew, 
	    "\nStd Skew = ", $StdSkew, "\n";
} else {
	print "Std Dev = 0 or N <=3; Skipping Skewness, Std Skewness cal'n.\n";
}
 	
exit 0;

sub numerically { $a <=> $b; }