--- On Wed, 1/7/09, Artie Ziff <artie.z...@gmail.com> wrote:
From: Artie Ziff <artie.z...@gmail.com> Subject: [Tutor] simple array access To: Tutor@python.org Date: Wednesday, January 7, 2009, 9:12 PM Hello, I used python list comprehension to create a grid (list of lists) of Objects (instances of MyItem class). Can anyone make recommendations to achieve a simple access to the elements. My attempt at array access (like this: array[1,2] ) does not work. What am I overlooking? Thanks in advance! :) If anyone has time to show a better way to achieve same, then I am interested to learn! :) ### from pprint import * class MyItem: def __init__(self, value): self.data=value def __repr__(self): return 'MyItem(%s)' % (self.data) class Grid: def __init__(self, x, y, value): self.data = [[MyItem(float(value)) for i in range(x)] for j in range(y)] if __name__ == "__main__": grid = Grid(2, 3, 0.42) pprint(grid) pprint(grid.data) # next line fails to access array element pprint (grid.data[1,2]) # EOF # OUTPUT: <__main__.Grid instance at 0x7beb8> [[MyItem(0.42), MyItem(0.42)], [MyItem(0.42), MyItem(0.42)], [MyItem(0.42), MyItem(0.42)]] Traceback (most recent call last): File "multidim04.py", line 20, in <module> pprint (grid.data[1,2]) TypeError: list indices must be integers Cheers, Art ## There are probably much easier, elegant ways to populate a list ## This is fast enough to generate to express the idea ## There is a row/col method also but I haven't used it ## List comprehensions may be prettier/faster (check Kent's page I believe he has ## write up on them some_sequence = [] i = 0 k = [] for i in range (10): k.append(i) for i in range (10): some_sequence.append(k) for stuff in some_sequence: print stuff print "Some sequence has 10 outer indexes beginning at [0] and ending at [9]" print "The first element of index [0] is the value 0, and can be accessed at some_sequence[0][0] :" + str(some_sequence[0][0]) print "The last element of index [9] ## the 10th line or index is the value 9, and can be accessed at some_sequence[9][9] :" + str(some_sequence[9][9])
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