Generating 2-d array of binary numbers in python

Question

So this is what im trying in Python.`

input = []
for i in range(10):
  n = getBin(i, 4)
  input.append(n)
print input

It is giving as:

['0000', '0001', '0010', '0011', '0100', 
 '0101', '0110', '0111', '1000', '1001']

And what I need is as:

[[0, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0], [0, 0, 1, 1], [0, 1, 0, 0],
 [0, 1, 0, 1], [0, 1, 1, 0], [0, 1, 1, 1], [1, 0, 0, 0], [1, 0, 0, 1]]

mhlester · Accepted Answer · 2014-02-13 06:24:36Z

1

Using itertools.product with (0, 1) and 4 repeats:

input = [list(x) for x in itertools.product((0, 1), repeat=4)]

If you're ok with a list of tuples rather than of lists, you can simply do:

input = list(itertools.product((0, 1), repeat=4))

Or simplest of all, if you will be iterating over it anyway, there's no need to make it a list:

input = itertools.product((0, 1), repeat=4)

Lastly, (0, 1) could be range(2), but that's hardly an improvement

itertools.product generally tries to return in the same format you gave it. So by feeding a string, it returns a string. Feed it a list and it...almost returns a list (returns a tuple)

edited Feb 13, 2014 at 6:24

answered Feb 13, 2014 at 6:19

mhlester

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5 Comments

Grijesh Chauhan Over a year ago

Not sure but I think OP don't want this technique.

lkkkk Over a year ago

The first option is what i want.In the same way i want for floating points and the number will contain around 10 digits after point (ex. 0.0001221215). The number will vary from 0 to 2500.

mhlester Over a year ago

@GrijeshChauhan, I assumed this new question was an implementation detail of the previous, as previous output was the input to this question. Using that knowledge, I'm changing the itertools.product in getBin to provide the solution without any additional layer of code

lkkkk Over a year ago

@GrijeshChauhan ok.. i m adding new question for the above

lkkkk Over a year ago

how can i save these binary numbers in txt file.Each line should contain 4 bits as from above question.

thefourtheye · Accepted Answer · 2014-02-13 06:20:26Z

1

Your getBin returns a binary number in string format, we convert each and every character to an integer with int and return a list.

result = [map(int, getBin(i,4)) for i in range(10)]

For example,

def getBin(number, total):
    return bin(number)[2:].zfill(total)

result = [map(int, getBin(i, 4)) for i in range(10)]

print result

Output

[[0, 0, 0, 0],
 [0, 0, 0, 1],
 [0, 0, 1, 0],
 [0, 0, 1, 1],
 [0, 1, 0, 0],
 [0, 1, 0, 1],
 [0, 1, 1, 0],
 [0, 1, 1, 1],
 [1, 0, 0, 0],
 [1, 0, 0, 1]]

answered Feb 13, 2014 at 6:20

thefourtheye

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2 Comments

Grijesh Chauhan Over a year ago

is getBin any library function?

thefourtheye Over a year ago

@GrijeshChauhan Nope. OP hasn't shown how that is implemented. So, I had to implement it on my own. Its there in my answer itself. Please check.

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