Reshaping a 1-D Array to a Multidimensional Array

Convert a 1D array to a 2D array in numpy

You want to reshape the array.

B = np.reshape(A, (-1, 2))

where -1 infers the size of the new dimension from the size of the input array.

Numpy reshape 1d to 2d array with 1 column

You could do -

ar.reshape(ar.shape[0],-1)

That second input to reshape : -1 takes care of the number of elements for the second axis. Thus, for a 2D input case, it does no change. For a 1D input case, it creates a 2D array with all elements being "pushed" to the first axis because of ar.shape[0], which was the total number of elements.

Sample runs

1D Case :

In [87]: ar
Out[87]: array([ 0.80203158,  0.25762844,  0.67039516,  0.31021513,  0.80701097])

In [88]: ar.reshape(ar.shape[0],-1)
Out[88]: 
array([[ 0.80203158],
       [ 0.25762844],
       [ 0.67039516],
       [ 0.31021513],
       [ 0.80701097]])

2D Case :

In [82]: ar
Out[82]: 
array([[ 0.37684126,  0.16973899,  0.82157815,  0.38958523],
       [ 0.39728524,  0.03952238,  0.04153052,  0.82009233],
       [ 0.38748174,  0.51377738,  0.40365096,  0.74823535]])

In [83]: ar.reshape(ar.shape[0],-1)
Out[83]: 
array([[ 0.37684126,  0.16973899,  0.82157815,  0.38958523],
       [ 0.39728524,  0.03952238,  0.04153052,  0.82009233],
       [ 0.38748174,  0.51377738,  0.40365096,  0.74823535]])

How to reshape a 1d array to a 3d array with diffrerent size of 2d arrays?

a multidimensional array can't have dimensions with different size.

but if you want a tuple you will need to split the array in 2 parts, the first that match in size with the 3x3 array and the second that match the 3x2, at this point you'll have 2 one dimensional array, then reshape them

arr1 = arr1.reshape((3,3)) 
arr2 = arr2.reshape((3,2))

tuple = arr1, arr2 

How do I reshape a NumPy multi dimensional array to another array with the same dimensions, but different shape?

The function you are looking for is np.moveaxis() which lets you move a source axis to its destination.

>>> arr = np.random.random((1,76,76,255))
>>> 
>>> arr.shape
(1, 76, 76, 255)
>>> arr2 = np.moveaxis(arr, 3, 1)
>>> arr2.shape
(1, 255, 76, 76)
>>> 

Please note that these axes are 0-indexed

Python reshaping 1D array into 2D array by 'rows' or 'columns'

Use np.transpose.

import numpy as np

print(np.arange(9).reshape(3,3).transpose())

Output:

[[0 3 6]
 [1 4 7]
 [2 5 8]]

How to reshape a flattened array to a multidimensional array in arbitray shape in Javascript?

Here's my solution:

---

const A = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12];
const C = [3, 4];

function unflattenArray(arr, dim) {
  let elemIndex = 0;

  if (!dim || !arr) return [];

  function _nest(dimIndex) {
    let result = [];

    if (dimIndex === dim.length - 1) {
      result = result.concat(arr.slice(elemIndex, elemIndex + dim[dimIndex]));
      elemIndex += dim[dimIndex];
    } else {
      for (let i = 0; i < dim[dimIndex]; i++) {
        result.push(_nest(dimIndex + 1));
      }
    }

    return result;
  }
  return _nest(0);
}

console.log(unflattenArray(A, C));

Reshape 1D array to matrix 2D matrix

Might i suggest this change. it will work as i think you are passing a bad ar into the function:

import numpy as np
np.random.seed(25)
ar = np.random.randn(1000)
ar = ar * 100
ar = ar.astype('int8')
ar

def reshape(my_array):
    ar = np.reshape(my_array,(200,5))
    return ar

new_ar = reshape(ar)

---

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