''' Purpose: introduce some functions from module random
'''

import random # want random values, then we need the random module

print( 'By default, we can expect the random number generator to produce' )
print( 'a difference sequence of values every time we start it up' )

x = random.random()     # random() returns a float number from float interval [0, 1 )
y = random.random()     # because we did not set the seed, every time we run the program
                        # should assign different values to the variables

print( 'x:', x  ) # x will be a different float every time we run the program
print( 'y:', y  ) # y will also be different every time

print() ; input( 'Enter when ready: ' ); print()

# if we set the seed value, the random number generator is configured to
# produce the same sequence of random values from that point on.

random.seed( 1112 )     #  first number from seed( 1112 ) is always 0.28143470043335006.
x = random.random()     # how do we know this, we ran the

#random.seed( 1112 )     # program and recorded the value
y = random.random()     #seed allows you to repeat the same random number
# even though we are generating a different variable above, because we set the seed
#as the same number in line 22, we will get the same number for y as we did for x
# you can set the seed when using random.choice(): it will control the sequence
#of choices that are made

print( 'Because we set the seed to the same value before generating values for x' )
print( 'y, they are going to have the same value' )

print( 'x:', x )
print( 'y:', y )

print() ; input( 'Enter when ready: ' ); print()

# let's make the seed random
random.seed() #if you don't give seed an argument, it just randomizes behavior
bottom = 2
top    = 7
step   = 2

# function random.randrange( x ) returns a random integer from interval [ 0, x );
#     that is, it generates a base x number

x = random.randrange( top ) #if you give a single value, it will generate random
                            #integer from interval [ 0, x )

print( 'randrange(', top, '):', x )

print() ; input( 'Enter when ready: ' ); print()

# function random.randrange( x, y ) returns a random integer from interval [ x, y )

x = random.randrange( bottom, top ) #can give it a range [ x, y )
print( 'randrange(', bottom, ',', top, '):', x )

print() ; input( 'Enter when ready: ' ); print()

# function random.randrange( x, y, s ) returns random integer value from interval
#     [ x, y ); numbers are of form x + ( i * s )

x = random.randrange( bottom, top, step ) #step up by a certain value from range
                                            # [ bottom, top )
                                            #step by default is 1

print( 'randrange(', bottom, ',', top, ',', step, '):', x )

print() ; input( 'Enter when ready: ' ); print()

# function random.choice( s ) if s is a string, returns a random character from s

keyboard = 'qwertyuiopasdfghjklzxcvbnm'

letter = random.choice( keyboard ) #give choice a sequence, and it will pick
#something from that sequence and hand it back

print( 'choice( \'' +  keyboard + '\' ):', letter )
# the \' means print an actual quote, don't take it as the start of a string
print() ; input( 'Enter when ready: ' ); print()

# function random.choice( s ) if s is a sequence, returns a random element from s

days = [ 'Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa' ]

day = random.choice( days )

print( 'choice(', days, '):', day )

print() ; input( 'Enter when ready: ' ); print()

# random.shuffle( s ) if s is a sequence, randomly reorders s

random.shuffle( days ) #give it a list, and it will mix up the order of the list
print( 'Days is now:', days ) #it manipulates the original list: does NOT produce

# a new list (you can modify lists, but not strings)

print()