CODEWITHSUNDEEP
pythonlist
Anonymous Entity
Anonymous Entity

Reputation: 3350

How do I create bidimensional table from list?

Starting with a list of tuples which represent points on a surface.

list = [(48, 228), (96, 204), (120, 192), ... ]

What is the pythonic way to create a new list, so we can call values from the original list, as if they were distributed on a grid?

Like this:

>>>print grid[0][0]
(48, 228)
>>>print grid[0][1]
(96, 204)

Upvotes: 1

Views: 179

Answers (2)

Iulius Curt
Iulius Curt

Reputation: 5114

This is a list comprehension that solves it:

l = [(48, 228), (96, 204), (120, 192), ... ]
# 'width' is the width of your bidimensional table (grid)
bidimensional = [l[a*width:(a+1)*width] for a in xrange(len(l)/width)]

Explained:

[  # make a list of:
  l[a*width:(a+1)*width]
    # get the 'a'-th slice of length 'width' of the initial list
  for a in xrange(len(l)/width)  # for 'len(l)/width' slices
]

Test:

>>> l = [(1, 11), (2, 22), (3, 33), (4, 44), (5, 55), (6, 66),(7, 77), (8, 88)]
>>> width = 2
>>> bidimensional = [l[a*width:(a+1)*width] for a in xrange(len(l)/width)]

>>> bidimensional
[[(1, 11), (2, 22)], [(3, 33), (4, 44)], [(5, 55), (6, 66)], [(7, 77), (8, 88)]]

>>> bidimensional[2][1]
(6, 66)

Upvotes: 0

Thorsten Kranz
Thorsten Kranz

Reputation: 12765

I don't really see the difficulty, maybe a simple grid=[list] would suffice.

If you want to have it as a fast 2d-array, use numpy:

import numpy as np
grid = np.array(list).reshape(1,-1)
print grid[0,1] #prints (96, 204)

If your data become larger or higher dimensional, always use numpy arrays, don't use lists-of-lists.

One remark: please don't call your variable list, it will hide the built-in method list.

Upvotes: 1

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