for loop modulo reversed countdown xrange dictionary Counter

# syntactic sugar for easily counting data
# https://docs.python.org/2/library/collections.html#collections.Counter
from collections import Counter
APPLE = 'apple'
BANANA = 'banana'

c = Counter([APPLE, BANANA])
print c  # Counter({'apple': 1, 'banana': 1})
c.clear()
print c  # Counter()
print c.get(APPLE)  # None

# print sum(c.values())
c[APPLE] += 1
c[APPLE] += 1
print c.get(APPLE)  # 1
c[BANANA] += 1

print c  # Counter({'apple': 2, 'banana': 1})

sorted_list = c.most_common()
if sorted_list:
    print 'max:', sorted_list.pop(0)  # max: ('apple', 2)

- - -

for i in xrange( 10 ):   # creates an iterator counting from 0 to 10 (more memory efficient than creating the whole list in memory)
    x = 0.1 * i
    print x,        # trailing comma removes the default print newline


for i in [ 2 , 3 , 6 , 14 ]:         # has an index variable i, uses the values from the list, ends with a colon
    print i , "=" , hex(i)


range( 7, 1000, 7 ) # returns an actual list of multiples of 7 under 1000


for i in xrange( 10, -1, -1):           # xrange cannot go beyond values of C integer, so for very large use range()
    print i       # counts down from  10 to 0

for i in reversed( xrange( 10 ) ):      # reversed changes the order of the xrange iterator
    print i       # counts down from  9 to 0



print "\n\nwhile if i==8 break" \
    " \ means code line print continued"
i = 5
# infinite loop
while 1:        # usually better as while True:
    print i
    i += 1
    if i == 8:
        print i
        break


print "range( 2 , 5 ) start stop before with if else is elif"
for i in range( 2 , 5 ):
    if i ==2:
        print "i == 2"
    elif i==3:
        print "elif i==" , i , "commas"
    else:
        print i


import math
print "\n\nmath.sqrt( 88 ) = " , math.sqrt( 88 )


fastconcat = ''.join( ["fast" , "string" , "list" , "concat"] )     # takes a list and joins it with no input
print fastconcat

# outputs [x, 3, b]  , in python 3 the map uses generator so it's performant =)
mylist = [ 'x', 3, 'b' ]
print '[%s]' % ', '.join( map( str, mylist ) )      # default str function is applied to all elements in the list



# Using a generator is the minimal memory footprint and allows access to the index and the value
def reverse_enum(L):
   for index in reversed(xrange(len(L))):
      yield index, L[index]

L = ['foo', 'bar', 'bas']
for index, item in reverse_enum(L):
   print index, item



counter = 0
while( counter < 50 ):
    sys.stdout.write( '.' )
    counter = counter + 1
    if counter % 10 == 0:
        print '\n'