#!/usr/bin/env python

import sys,os

defthreshold = 20
debug = 0
minint = 10

try:
    ifname = sys.argv[1]
except IndexError:
    print 'Usage: ',sys.argv[0],' inputfile [threshold]'
    sys.exit(1)

try:
    threshold = int(sys.argv[2])
except IndexError:
    threshold = defthreshold
except ValueError:
    print 'Usage: ',sys.argv[0],' inputfile [threshold]'
    sys.exit(1)

try:
    ifile = open(ifname,'r')
except IOError:
    print 'Error opening file ',ifname,' for input'
    sys.exit(1)

lnr = 0
lastnr = 0
inr = 0
lastpeak = 0
while 1:
    lnr += 1
    line = ifile.readline()
# EOF
    if line == '':
        break
# read a line
    try:
        newnr = int(line)
    except ValueError:
        print 'Parse error at line %d: %s' % (lnr,line)
# compare with last value assuming there is a large value (i.e. not for the first line)
    if lastnr == 0:
        lastnr = newnr
    else:
        if (lastnr - newnr > threshold):
            if debug:
                print 'Peak at %d, previous: %d, new: %d' % (lnr,lastnr,newnr)
# calculate interval from last peak if there was a previous peak
            if lastpeak == 0:
                lastpeak = lnr
            else:
# ignore if two peaks are very close together (probably oscillation)
                if (lnr-lastpeak >= minint):
                    inr += 1
                    print 'Interval %d: %d' % (inr,lnr-lastpeak)
                    lastpeak = lnr