Source code for gt_average

"""
This program finds all values greater than average, 
then returns the number of such values, and the median of these values.

Pseudo code::

      List of co2_levels is given
      Find average value in the list
      Find the list of values greater than average, 
      Put them in a list
      Return the length of the list (number of such values)
      Find the median and print

"""

def median(L):
     """Given a list of values, returns the median value. """

     vals = list(L) ## make a copy to make sure the original list is not changed
     vals.sort()

     numvalues = len(vals)
     medianindex = numvalues/2
     if numvalues%2 == 1:  ##Odd number of values
         return vals[medianindex]
     else: ## Even number of values, return the average of two middle values
         return sum(vals[medianindex-1:medianindex+1])/2.0



######## Main program starts here.

co2_levels = [ 320.03, 322.16, 328.07, 333.91, 341.47,\
               348.92, 357.29, 363.77, 371.51, 382.47, 392.95 ]

avg = float(sum(co2_levels))/len(co2_levels)

gtavg = []

for value in co2_levels:
    if value > avg:
        gtavg.append(value)
        
print "average is", avg
print "Values greater than average", gtavg
print "%d values greater than average" %(len(gtavg))

medianval = median(gtavg)

print "Median value", medianval