Write a function strides() that given an array of tokens T as numpy array, using strided trick, returns [T[0:50], T[10:60], T[20: 70] ... ]
Write a function strides() that given an array of tokens T as numpy array, using strided trick, returns [T[0:50], T[10:60], T[20: 70] ... ]
# Implementing the strides function with NumPy's stride tricks The task is to create a function that generates overlapping windows of a fixed size from a NumPy array, using stride tricks for efficiency. Let me implement this:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 | import numpy as np from numpy.lib.stride_tricks import as_strided def strides(T): """ Given an array of tokens T as numpy array, returns a list of overlapping windows [T[0:50], T[10:60], T[20:70], ...] using NumPy's stride tricks for efficiency. Args: T (numpy.ndarray): Input array of tokens Returns: list: List of views of the original array with stride 10 and window size 50 """ # Ensure T is a numpy array T = np.asarray(T) # Define window size and stride window_size = 50 stride = 10 # Calculate number of windows n = len(T) num_windows = max(0, (n - window_size) // stride + 1) if num_windows <= 0: return [] # Create a strided view of the array # shape: (number of windows, size of each window) # strides: (bytes to move to next window, bytes to move to next element) strided_array = as_strided( T, shape=(num_windows, window_size), strides=(T.itemsize * stride, T.itemsize) ) # Convert to list of arrays as requested result = [strided_array[i] for i in range(num_windows)] return result |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 | import numpy as np from numpy.lib.stride_tricks import as_strided def strides(T): """ Given an array of tokens T as numpy array, returns a list of overlapping windows [T[0:50], T[10:60], T[20:70], ...] using NumPy's stride tricks for efficiency. Args: T (numpy.ndarray): Input array of tokens Returns: list: List of views of the original array with stride 10 and window size 50 """ # Ensure T is a numpy array T = np.asarray(T) # Define window size and stride window_size = 50 stride = 10 # Calculate number of windows n = len(T) num_windows = max(0, (n - window_size) // stride + 1) if num_windows <= 0: return [] # Create a strided view of the array # shape: (number of windows, size of each window) # strides: (bytes to move to next window, bytes to move to next element) strided_array = as_strided( T, shape=(num_windows, window_size), strides=(T.itemsize * stride, T.itemsize) ) # Convert to list of arrays as requested result = [strided_array[i] for i in range(num_windows)] return result |
Testing if the previous output contains the string as_strided
: True
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 | import numpy as np from numpy.lib.stride_tricks import as_strided def strides(T): """ Given an array of tokens T as numpy array, returns a list of overlapping windows [T[0:50], T[10:60], T[20:70], ...] using NumPy's stride tricks for efficiency. Args: T (numpy.ndarray): Input array of tokens Returns: list: List of views of the original array with stride 10 and window size 50 """ # Ensure T is a numpy array T = np.asarray(T) # Define window size and stride window_size = 50 stride = 10 # Calculate number of windows n = len(T) num_windows = max(0, (n - window_size) // stride + 1) if num_windows <= 0: return [] # Create a strided view of the array # shape: (number of windows, size of each window) # strides: (bytes to move to next window, bytes to move to next element) strided_array = as_strided( T, shape=(num_windows, window_size), strides=(T.itemsize * stride, T.itemsize) ) # Convert to list of arrays as requested result = [strided_array[i] for i in range(num_windows)] return result answer = strides(np.arange(100)).shape expected = (6, 50) assert answer == expected, f'Wrong answer; got {answer} instead of {expected}' answer = strides(np.arange(100)).sum() expected = 14850 assert answer == expected, f'Wrong answer; got {answer} instead of {expected}' print('All tests passed') |
Traceback (most recent call last):
File "/usr/src/app/main.py", line 48, in <module>
answer = strides(np.arange(100)).shape
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'list' object has no attribute 'shape'
Testing if the previous output contains the string All tests passed
: False
Write a function strides() that given an array of tokens T as numpy array, using strided trick, returns [T[0:50], T[10:60], T[20: 70] ... ]
Write a function strides() that given an array of tokens T as numpy array, using strided trick, returns [T[0:50], T[10:60], T[20: 70] ... ]
# Implementing a Function to Create Strided Token Windows To create sliding windows of tokens with a fixed stride, I'll use NumPy's strided trick which is memory-efficient as it creates views of the original array rather than copying data.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | import numpy as np from numpy.lib.stride_tricks import as_strided def strides(T): """ Given an array of tokens T, returns a list of strided windows. Each window is of size 50, with a stride of 10 elements. Args: T (numpy.ndarray): Input array of tokens Returns: list: List of array slices [T[0:50], T[10:60], T[20:70], ...] """ # Set window parameters window_size = 50 stride = 10 # Calculate number of complete windows n_windows = (len(T) - window_size) // stride + 1 if n_windows <= 0: return [] # Create a strided view of the original array windows_view = as_strided( T, shape=(n_windows, window_size), strides=(stride * T.strides[0], T.strides[0]) ) # Convert to list of arrays return [windows_view[i] for i in range(n_windows)] |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | import numpy as np from numpy.lib.stride_tricks import as_strided def strides(T): """ Given an array of tokens T, returns a list of strided windows. Each window is of size 50, with a stride of 10 elements. Args: T (numpy.ndarray): Input array of tokens Returns: list: List of array slices [T[0:50], T[10:60], T[20:70], ...] """ # Set window parameters window_size = 50 stride = 10 # Calculate number of complete windows n_windows = (len(T) - window_size) // stride + 1 if n_windows <= 0: return [] # Create a strided view of the original array windows_view = as_strided( T, shape=(n_windows, window_size), strides=(stride * T.strides[0], T.strides[0]) ) # Convert to list of arrays return [windows_view[i] for i in range(n_windows)] |
Testing if the previous output contains the string as_strided
: True
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 | import numpy as np from numpy.lib.stride_tricks import as_strided def strides(T): """ Given an array of tokens T, returns a list of strided windows. Each window is of size 50, with a stride of 10 elements. Args: T (numpy.ndarray): Input array of tokens Returns: list: List of array slices [T[0:50], T[10:60], T[20:70], ...] """ # Set window parameters window_size = 50 stride = 10 # Calculate number of complete windows n_windows = (len(T) - window_size) // stride + 1 if n_windows <= 0: return [] # Create a strided view of the original array windows_view = as_strided( T, shape=(n_windows, window_size), strides=(stride * T.strides[0], T.strides[0]) ) # Convert to list of arrays return [windows_view[i] for i in range(n_windows)] answer = strides(np.arange(100)).shape expected = (6, 50) assert answer == expected, f'Wrong answer; got {answer} instead of {expected}' answer = strides(np.arange(100)).sum() expected = 14850 assert answer == expected, f'Wrong answer; got {answer} instead of {expected}' print('All tests passed') |
Traceback (most recent call last):
File "/usr/src/app/main.py", line 40, in <module>
answer = strides(np.arange(100)).shape
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'list' object has no attribute 'shape'
Testing if the previous output contains the string All tests passed
: False