# datastructures.py
'''
More on lists and tuples and dictionaries.
'''

#
# List Comprehensions.
#

squares = [x**2 for x in range(10)]
[(x, y) for x in [1, 2, 3] for y in [3, 1, 4]]

# Some control.
[x for x in range(10) if x > 5]

# Nested list comprehension.
matrix = [[x+10*y for x in range(3)] for y in range(3)]

# Transpose.
zip(*matrix)

# Delete and object.
del(matrix)


#
# Tuples
#

(x, y) = (4, 3)
tt = (x, y)
len(tt)

# Create a tuple with 0 and 1 item.
singleton = (2, )

# Transform an iterable into a tuple.
(x, y) = tuple([1, 2])


#
# Dictionaries (associative arrays)
#

tel = {'jack': 4098, 'sape': 4139}
tel['guido'] = 4127
tel.keys()
tel.items()
tel.values()
del(tel['sape'])

'guido' in tel
'jack' not in tel
dict([('sape', 4139), ('guido', 4127), ('jack', 4098)])

# Looping with dictionaries.
knights = {'gallahad': 'the pure', 'robin': 'the brave'}
for k, v in knights.items():
    print(k, v)


#
# Comparing data structures.
#

(1, 2, 3) < (1, 2, 4)
[1, 2, 3] < [1, 2, 4]
'ABC' < 'C' < 'Pascal' < 'Python'
(1, 2, 3, 4) < (1, 2, 4)
(1, 2) < (1, 2, -1)