how to convert a x^2 long list to a list of shape (x,x)

Question

Im in python, I have a list with a length 784 (which i extracted from a 28x28 image ) and now i want to arrange it in a way i can use it in tensor-flow to be used with a trained model but the problem is that the NN needs to have a 28,28 shaped array but my current array is of shape (784,)

I tried to use some for loops for this but i have no luck in successfully creating a system to carry this out , please help

i figured out that i need to use this structure

for i in range(res):
   for a in range(0,res):

       mnistFormat.append(grascalePix[a]) #mnistFormat is an innitially empty list
#and grascale has my 784 grayscale pixles

but i cant figure out what should go in the range function of the for loop to make this possible

For example lets say i have a sample 4x4 image's pixel list >

grayscalePix = [255,255,255,255,255,100,83,200,255,50,60,255,30,1,46,255]

this is a Row by Row representation , which means the first 4 elements are the first ---- row

i want to arrange them into a list of shape (4,4) mnistFormat = [255,255,255,255],[255,100,83,200],[255,50,60,255],[30,1,46,255]

Just keep in mind this is sample , the real data is 784 elements long and i dont have much experince in numpy

Does this answer your question? [Reshape an array in NumPy](https://stackoverflow.com/questions/14476415/reshape-an-array-in-numpy) — buran, Jan 12 '21 at 14:04

score 1 · Accepted Answer · answered Jan 12 '21 at 14:03

1

numpy might help you there very easily:

mnistFormat = np.array(grascalePix).reshape((np.sqrt(len()),-1))

answered Jan 12 '21 at 14:03

adir abargil

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can i also ensure that the first row of the pixel list (the first 28 values) are arranged as the first list in the mnist list(thus i want the mnist list to be a list of lists) – Shaurya Mittal Jan 12 '21 at 14:05
i looked at some reshape questions on SO but those do not place my numbers in the correct position – Shaurya Mittal Jan 12 '21 at 14:08
please provide example to demonstrate the order, in your question ofcorse – adir abargil Jan 12 '21 at 14:09
I have added the example – Shaurya Mittal Jan 12 '21 at 18:33
i think the reshape gives what you want, maybe what you mean is to turn your result to list so just do `arr.tolist()` – adir abargil Jan 12 '21 at 18:50
okay i didnt use arr.tolist() but your answere works so tq for that – Shaurya Mittal Jan 13 '21 at 09:30

how to convert a x^2 long list to a list of shape (x,x)

1 Answers1