Bruhnke, Angelica wrote:
> I'm new to python programming so this question will probably be a no
> brainer for the experienced programmer. I'm trying to create a 10x10 array
> of zeros and then framing it with a border of ones.
So the final array is 12x12.
>
> Output should look like this:
>
> [[ 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]
>
> [ 1. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
>
> [ 1. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
>
> [ 1. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
>
> [ 1. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
>
> [ 1. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
>
> [ 1. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
>
> [ 1. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
>
> [ 1. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
>
> [ 1. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
>
> [ 1. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 1.]
>
> [ 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]]
>
>
>
> This is the code I've written:
>
> a = np.ones ((1,10))
>
> print a
>
> b = np.zeros ((10,10))
>
> print b
>
> c = np.vstack ((b,a))
>
> print c
>
>
> This is my output:
>
> [[ 1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]]
> [[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]]
> [[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]
> [ 1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]]?
>
> As you can see I have too many zeros once I stack them and don't have the
> ones framing the sides vertically.
>
> Any guidance on where I'm going astray?
Below I'm using the dimensions 4x4. To get
1 1 1 1
1 0 0 1
1 0 0 1
1 1 1 1
you can vstack()
>>> np.vstack(([1,1], [[0,0],[0,0]], [1,1]))
array([[1, 1],
[0, 0],
[0, 0],
[1, 1]])
and use hstack() to add ones to the sides:
>>> side = [[1]]*4
>>> np.hstack((side, mid, side))
array([[1, 1, 1, 1],
[1, 0, 0, 1],
[1, 0, 0, 1],
[1, 1, 1, 1]])
The same with ones() and zeros(), put into a function:
>>> def frame(N):
... horz = np.ones((1, N))
... inner = np.zeros((N, N))
... vert = np.ones((N+2, 1))
... mid = np.vstack((horz, inner, horz))
... return np.hstack((vert, mid, vert))
...
>>> frame(3)
array([[ 1., 1., 1., 1., 1.],
[ 1., 0., 0., 0., 1.],
[ 1., 0., 0., 0., 1.],
[ 1., 0., 0., 0., 1.],
[ 1., 1., 1., 1., 1.]])
>>> frame(1)
array([[ 1., 1., 1.],
[ 1., 0., 1.],
[ 1., 1., 1.]])
Personally I'd probably use a simpler approach. Start with all ones and then
set the inner values to 0:
>>> def frame2(N):
... a = np.ones((N+2, N+2))
... a[1: -1, 1: -1] = 0
... return a
...
>>> frame2(2)
array([[ 1., 1., 1., 1.],
[ 1., 0., 0., 1.],
[ 1., 0., 0., 1.],
[ 1., 1., 1., 1.]])
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