''' Purpose: Remind you about subscript indexing.
            Introduce slicing
'''

# get access to local module pause.
import pause       

# operator [] is the string index operator -- it provides access to
# a string subsequence. depending upon its operands it is all called
# subscripting and slicing

print( '##### [] is the string index operator' )
s = 'obliviator'
print( 's =', s )
print( '    0123456789' )

### pause to think what has happened

pause.enter_when_ready()

print( '##### if the [] operand brackets an int, it is subscripting' )
x = s[ 0 ]
y = s[ 4 ]
z = s[ 9 ]

print( 's[ 0 ] = ', x )
print( 's[ 4 ] = ', y )
print( 's[ 9 ] = ', z )

### pause to think what has happened

pause.enter_when_ready()

print( '##### if the [] operand brackets a : expession, it is slicing' )

print()

s = input( 'Enter your philosphy of life: ' )

print( 'philosophy:', s )

n     = len( s )
left  = 1
right = n // 2

s1 = s[ left : right ]
s2 = s[ : right ]
s3 = s[ left :   ]
s4 = s[ : ]

print( 's[', left, ':', right, ']  = ', s1 )
print( 's[',       ':', right, ']  = ', s2 )
print( 's[', left, ':',        ']  = ', s3 )
print( 's[',       ':',        ']  = ', s4 )

### pause to think what has happened

pause.enter_when_ready()

# bonus -- stripping and splitting

# strings can produced strip versions of themselves -- a
# version without LEADING or TRAILING whitespace.  Internal
# whitespace is uneffected.  The ability comes from a
# a string's method split()
#            ------

print( '##### stripping' )

q = '   Look there is a   Blibbering Humdinger  '

q.strip()                   # q is uneffected. strip() produces
                            # a new string

print( "q = '" + q + "'"  )

### pause to think what has happened

pause.enter_when_ready()

# bonus -- stripping and splitting

# strings can produced strip versions of themselves -- a
# version without LEADING or TRAILING whitespace.  Internal
# whitespace is uneffected.  The ability comes from a
# a string's method split()
#            ------

print( '##### stripping' )

q = '   Look there is a   Blibbering Humdinger  '


s = q.strip()               # q is still uneffected, but s is a
                            # stripped version of s

print( "q = '" + q + "'"  )
print( "s = '" + s + "'" )

### pause to think what has happened

pause.enter_when_ready()

# strings can produce their component words.  The ability
# come from a string's  method split()
#                        ------

print( '##### splitting' )

f = 'bananas  $0.69'
c = 'SEAS CS 1112'

print( 'f = \'' + f + '\'' )
print( 'c = \'' + c + '\'' )

### pause to think what has happened

pause.enter_when_ready()

fruit, price = f.split()              # splits fruit into list of individual
                                      # words, which for this example is a
                                      # fruit and its cost

school, subject, number = c.split()   # splits person into list of indiviudal
                                      # words, which for this example is a
                                      # name, home planet, and age

print( fruit, 'costs', price, 'per pound' )
print( 'School:', school, '  subject:', subject,
            '  number:', number )

### pause to think what has happened

pause.enter_when_ready()

s1 = f.split()              # s1 is a 2-element list
s2 = c.split()              # s2 is a 3-element list

print( 's1 = ', s1 )
print( 's2 = ', s2 )

print()