Mengoptimumkan kod untuk mengalihkan kandungan dalam matriks dicari untuk digunakan dalam demo permainan 2048. Khususnya, fungsi diperlukan untuk mengalihkan nilai bukan sifar dalam matriks ke arah kiri, kanan, atas atau bawah.
Kod yang disediakan menawarkan pendekatan vektor yang diilhamkan oleh siaran lain:
def justify(a, invalid_val=0, axis=1, side='left'): """ Justifies a 2D array Parameters ---------- A : ndarray Input array to be justified axis : int Axis along which justification is to be made side : str Direction of justification. It could be 'left', 'right', 'up', 'down' It should be 'left' or 'right' for axis=1 and 'up' or 'down' for axis=0. """ if invalid_val is np.nan: mask = ~np.isnan(a) else: mask = a!=invalid_val justified_mask = np.sort(mask,axis=axis) if (side=='up') | (side=='left'): justified_mask = np.flip(justified_mask,axis=axis) out = np.full(a.shape, invalid_val) if axis==1: out[justified_mask] = a[mask] else: out.T[justified_mask.T] = a.T[mask.T] return out
In [473]: a # input array Out[473]: array([[1, 0, 2, 0], [3, 0, 4, 0], [5, 0, 6, 0], [6, 7, 0, 8]]) In [474]: justify(a, axis=0, side='up') Out[474]: array([[1, 7, 2, 8], [3, 0, 4, 0], [5, 0, 6, 0], [6, 0, 0, 0]]) In [475]: justify(a, axis=0, side='down') Out[475]: array([[1, 0, 0, 0], [3, 0, 2, 0], [5, 0, 4, 0], [6, 7, 6, 8]]) In [476]: justify(a, axis=1, side='left') Out[476]: array([[1, 2, 0, 0], [3, 4, 0, 0], [5, 6, 0, 0], [6, 7, 8, 0]]) In [477]: justify(a, axis=1, side='right') Out[477]: array([[0, 0, 1, 2], [0, 0, 3, 4], [0, 0, 5, 6], [0, 6, 7, 8]])
Untuk tatasusunan n-dimensi generik, kod boleh diubah suai seperti berikut:
def justify_nd(a, invalid_val, axis, side): """ Justify ndarray for the valid elements (that are not invalid_val). Parameters ---------- A : ndarray Input array to be justified invalid_val : scalar invalid value axis : int Axis along which justification is to be made side : str Direction of justification. Must be 'front' or 'end'. So, with 'front', valid elements are pushed to the front and with 'end' valid elements are pushed to the end along specified axis. """ pushax = lambda a: np.moveaxis(a, axis, -1) if invalid_val is np.nan: mask = ~np.isnan(a) else: mask = a!=invalid_val justified_mask = np.sort(mask,axis=axis) if side=='front': justified_mask = np.flip(justified_mask,axis=axis) out = np.full(a.shape, invalid_val) if (axis==-1) or (axis==a.ndim-1): out[justified_mask] = a[mask] else: pushax(out)[pushax(justified_mask)] = pushax(a)[pushax(mask)] return out
In [87]: a Out[87]: array([[[54, 57, 0, 77], [77, 0, 0, 31], [46, 0, 0, 98], [98, 22, 68, 75]], [[49, 0, 0, 98], [ 0, 47, 0, 87], [82, 19, 0, 90], [79, 89, 57, 74]], [[ 0, 0, 0, 0], [29, 0, 0, 49], [42, 75, 0, 67], [42, 41, 84, 33]], [[ 0, 0, 0, 38], [44, 10, 0, 0], [63, 0, 0, 0], [89, 14, 0, 0]]])
Ke 'depan', sepanjang paksi =0 :
In [88]: justify_nd(a, invalid_val=0, axis=0, side='front') Out[88]: array([[[54, 57, 0, 77], [77, 47, 0, 31], [46, 19, 0, 98], [98, 22, 68, 75]], [[49, 0, 0, 98], [29, 10, 0, 87], [82, 75, 0, 90], [79, 89, 57, 74]], [[ 0, 0, 0, 38], [44, 0, 0, 49], [42, 0, 0, 67], [42, 41, 84, 33]], [[ 0, 0, 0, 0], [ 0, 0, 0, 0], [63, 0, 0, 0], [89, 14, 0, 0]]])
Sepanjang paksi=1 :
In [89]: justify_nd(a, invalid_val=0, axis=1, side='front') Out[89]: array([[[54, 57, 68, 77], [77, 22, 0, 31], [46, 0, 0, 98], [98, 0, 0, 75]], [[49, 47, 57, 98], [82, 19, 0, 87], [79, 89, 0, 90], [ 0, 0, 0, 74]], [[29, 75, 84, 49], [42, 41, 0, 67], [42, 0, 0, 33], [ 0, 0, 0, 0]], [[44, 10, 0, 38], [63, 14, 0, 0], [89, 0, 0, 0], [ 0, 0, 0, 0]]])
Sepanjang paksi=2 :
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