Sliding/Moving window operations in rasters and arrays

DanPatterson_Retired

Sliding/Moving windows ...

This is the companion to block functions introduced earlier.  I will keep it simple.  The stats functions for rasters with and without nodata values still apply to this type of treatment.  The only difference is how the sub-arrays are generated.  I won't get into the details of how they are done here, but the stride function uses some pretty tricky handling of the input array structure to parse out the moving windows.

Remember, block functions move one window size across and down, per movement cycle.  Sliding functions move one cell across and down and sample the cell based on the window size...hence, there are many more windows to sample in sliding function than in block functions.  I will just show the code snippets and you can play on your own.  I have posted sample timing results for comparative purposes for both implementations.

Code section and comments
The stride_tricks does the work.  You can examine the code in the ...site-packages, numpy lib folder. functools provides decorator capabilities.  I tend to import it by default since I use decorators a lot for timing and documentation functions.  The textwrap module provide several functions, with dedent being useful for output documentation.  The numpy set_printoptions function allows you to control the appearance of output.  The version here is quite simplified...refer to the documentation for more information. Stride and block functions provide the means to sample the input array according to the type of data, the size and layout.  You must read the documentation and experiment in order to fully understand.  It really messes with your head and makes the Rubic's cube look simple. The decorator and timer functions I have talked about before.  Refer to my previous blogs for more information.
imports <SPAN class="keyword token">import</SPAN> numpy <SPAN class="keyword token">as</SPAN> np <SPAN class="keyword token">from</SPAN> numpy<SPAN class="punctuation token">.</SPAN>lib<SPAN class="punctuation token">.</SPAN>stride_tricks <SPAN class="keyword token">import</SPAN> as_strided <SPAN class="keyword token">from</SPAN> functools <SPAN class="keyword token">import</SPAN> wraps <SPAN class="keyword token">from</SPAN> textwrap <SPAN class="keyword token">import</SPAN> dedent np<SPAN class="punctuation token">.</SPAN>set_printoptions<SPAN class="punctuation token">(</SPAN>edgeitems<SPAN class="operator token">=</SPAN><SPAN class="number token">3</SPAN><SPAN class="punctuation token">,</SPAN>linewidth<SPAN class="operator token">=</SPAN><SPAN class="number token">80</SPAN><SPAN class="punctuation token">,</SPAN>precision<SPAN class="operator token">=</SPAN><SPAN class="number token">2</SPAN><SPAN class="punctuation token">,</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; suppress<SPAN class="operator token">=</SPAN><SPAN class="token boolean">True</SPAN><SPAN class="punctuation token">,</SPAN>threshold<SPAN class="operator token">=</SPAN><SPAN class="number token">100</SPAN><SPAN class="punctuation token">)</SPAN> <SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN> slide (stride) and block functions <SPAN class="comment token">#---- functions ----</SPAN> <SPAN class="keyword token">def</SPAN> <SPAN class="token function">_check</SPAN><SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">,</SPAN> r_c<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="string token">"""Performs the array checks necessary for stride and block. &nbsp;&nbsp;&nbsp; : a&nbsp;&nbsp; - Array or list. &nbsp;&nbsp;&nbsp; : r_c - tuple/list/array of rows x cols.&nbsp; &nbsp;&nbsp;&nbsp; :Attempts will be made to &nbsp;&nbsp;&nbsp; :&nbsp;&nbsp;&nbsp;&nbsp; produce a shape at least (1*c).&nbsp; For a scalar, the &nbsp;&nbsp;&nbsp; :&nbsp;&nbsp;&nbsp;&nbsp; minimum shape will be (1*r) for 1D array or (1*c) for 2D &nbsp;&nbsp;&nbsp; :&nbsp;&nbsp;&nbsp;&nbsp; array if r<c.&nbsp; Be aware &nbsp;&nbsp;&nbsp; """</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="keyword token">if</SPAN> isinstance<SPAN class="punctuation token">(</SPAN>r_c<SPAN class="punctuation token">,</SPAN> <SPAN class="punctuation token">(</SPAN>int<SPAN class="punctuation token">,</SPAN> float<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; r_c <SPAN class="operator token">=</SPAN> <SPAN class="punctuation token">(</SPAN><SPAN class="number token">1</SPAN><SPAN class="punctuation token">,</SPAN> int<SPAN class="punctuation token">(</SPAN>r_c<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp; r<SPAN class="punctuation token">,</SPAN> c <SPAN class="operator token">=</SPAN> r_c &nbsp;&nbsp;&nbsp; a <SPAN class="operator token">=</SPAN> np<SPAN class="punctuation token">.</SPAN>atleast_2d<SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp; shp <SPAN class="operator token">=</SPAN> a<SPAN class="punctuation token">.</SPAN>shape &nbsp;&nbsp;&nbsp; r<SPAN class="punctuation token">,</SPAN> c <SPAN class="operator token">=</SPAN> r_c <SPAN class="operator token">=</SPAN> <SPAN class="punctuation token">(</SPAN> min<SPAN class="punctuation token">(</SPAN>r<SPAN class="punctuation token">,</SPAN> a<SPAN class="punctuation token">.</SPAN>shape<SPAN class="punctuation token">[</SPAN><SPAN class="number token">0</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">,</SPAN> min<SPAN class="punctuation token">(</SPAN>c<SPAN class="punctuation token">,</SPAN> shp<SPAN class="punctuation token">[</SPAN><SPAN class="number token">1</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">)</SPAN> <SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp; a <SPAN class="operator token">=</SPAN> np<SPAN class="punctuation token">.</SPAN>ascontiguousarray<SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="keyword token">return</SPAN> a<SPAN class="punctuation token">,</SPAN> shp<SPAN class="punctuation token">,</SPAN> r<SPAN class="punctuation token">,</SPAN> c<SPAN class="punctuation token">,</SPAN> tuple<SPAN class="punctuation token">(</SPAN>r_c<SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="keyword token">def</SPAN> <SPAN class="token function">stride</SPAN><SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">,</SPAN> r_c<SPAN class="operator token">=</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="number token">3</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">3</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="string token">"""Provide a 2D sliding/moving view of an array.&nbsp; &nbsp;&nbsp;&nbsp; :&nbsp; There is no edge correction for outputs. &nbsp;&nbsp;&nbsp; : &nbsp;&nbsp;&nbsp; :Requires &nbsp;&nbsp;&nbsp; :-------- &nbsp;&nbsp;&nbsp; : a - array or list, usually a 2D array.&nbsp; Assumes rows is >=1, &nbsp;&nbsp;&nbsp; :&nbsp;&nbsp;&nbsp;&nbsp; it is corrected as is the number of columns. &nbsp;&nbsp;&nbsp; : r_c - tuple/list/array of rows x cols.&nbsp; Attempts&nbsp; to &nbsp;&nbsp;&nbsp; :&nbsp;&nbsp;&nbsp;&nbsp; produce a shape at least (1*c).&nbsp; For a scalar, the &nbsp;&nbsp;&nbsp; :&nbsp;&nbsp;&nbsp;&nbsp; minimum shape will be (1*r) for 1D array or 2D &nbsp;&nbsp;&nbsp; :&nbsp;&nbsp;&nbsp;&nbsp; array if r<c.&nbsp; Be aware &nbsp;&nbsp;&nbsp; """</SPAN> &nbsp;&nbsp;&nbsp; a<SPAN class="punctuation token">,</SPAN> shp<SPAN class="punctuation token">,</SPAN> r<SPAN class="punctuation token">,</SPAN> c<SPAN class="punctuation token">,</SPAN> r_c <SPAN class="operator token">=</SPAN> _check<SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">,</SPAN> r_c<SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp; shape <SPAN class="operator token">=</SPAN> <SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">.</SPAN>shape<SPAN class="punctuation token">[</SPAN><SPAN class="number token">0</SPAN><SPAN class="punctuation token">]</SPAN> <SPAN class="operator token">-</SPAN> r <SPAN class="operator token">+</SPAN> <SPAN class="number token">1</SPAN><SPAN class="punctuation token">,</SPAN> a<SPAN class="punctuation token">.</SPAN>shape<SPAN class="punctuation token">[</SPAN><SPAN class="number token">1</SPAN><SPAN class="punctuation token">]</SPAN> <SPAN class="operator token">-</SPAN> c <SPAN class="operator token">+</SPAN> <SPAN class="number token">1</SPAN><SPAN class="punctuation token">)</SPAN> <SPAN class="operator token">+</SPAN> r_c &nbsp;&nbsp;&nbsp; strides <SPAN class="operator token">=</SPAN> a<SPAN class="punctuation token">.</SPAN>strides <SPAN class="operator token">*</SPAN> <SPAN class="number token">2</SPAN> &nbsp;&nbsp;&nbsp; a_s <SPAN class="operator token">=</SPAN> <SPAN class="punctuation token">(</SPAN>as_strided<SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">,</SPAN> shape<SPAN class="operator token">=</SPAN>shape<SPAN class="punctuation token">,</SPAN> strides<SPAN class="operator token">=</SPAN>strides<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">.</SPAN>squeeze<SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN>&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; <SPAN class="keyword token">return</SPAN> a_s <SPAN class="keyword token">def</SPAN> <SPAN class="token function">block</SPAN><SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">,</SPAN> r_c<SPAN class="operator token">=</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="number token">3</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">3</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="string token">"""See _check and/or stride for documentation.&nbsp; This function &nbsp;&nbsp;&nbsp; :&nbsp; moves in increments of the block size, rather than sliding &nbsp;&nbsp;&nbsp; :&nbsp; by one row and column &nbsp;&nbsp;&nbsp; : &nbsp;&nbsp;&nbsp; """</SPAN> &nbsp;&nbsp;&nbsp; a<SPAN class="punctuation token">,</SPAN> shp<SPAN class="punctuation token">,</SPAN> r<SPAN class="punctuation token">,</SPAN> c<SPAN class="punctuation token">,</SPAN> r_c <SPAN class="operator token">=</SPAN> _check<SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">,</SPAN> r_c<SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp; shape <SPAN class="operator token">=</SPAN> <SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">.</SPAN>shape<SPAN class="punctuation token">[</SPAN><SPAN class="number token">0</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="operator token">/</SPAN>r<SPAN class="punctuation token">,</SPAN> a<SPAN class="punctuation token">.</SPAN>shape<SPAN class="punctuation token">[</SPAN><SPAN class="number token">1</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="operator token">/</SPAN>c<SPAN class="punctuation token">)</SPAN> <SPAN class="operator token">+</SPAN> r_c &nbsp;&nbsp;&nbsp; strides <SPAN class="operator token">=</SPAN> <SPAN class="punctuation token">(</SPAN>r<SPAN class="operator token">*</SPAN>a<SPAN class="punctuation token">.</SPAN>strides<SPAN class="punctuation token">[</SPAN><SPAN class="number token">0</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">,</SPAN> c<SPAN class="operator token">*</SPAN>a<SPAN class="punctuation token">.</SPAN>strides<SPAN class="punctuation token">[</SPAN><SPAN class="number token">1</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">)</SPAN> <SPAN class="operator token">+</SPAN> a<SPAN class="punctuation token">.</SPAN>strides &nbsp;&nbsp;&nbsp; a_b <SPAN class="operator token">=</SPAN> as_strided<SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">,</SPAN> shape<SPAN class="operator token">=</SPAN>shape<SPAN class="punctuation token">,</SPAN> strides<SPAN class="operator token">=</SPAN>strides<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">.</SPAN>squeeze<SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="keyword token">return</SPAN> a_b ‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN> timing decorator, decorated stat function and time test <SPAN class="keyword token">def</SPAN> <SPAN class="token function">delta_time</SPAN><SPAN class="punctuation token">(</SPAN>func<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="string token">"""simple timing decorator function"""</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="keyword token">import</SPAN> time &nbsp;&nbsp;&nbsp; @wraps<SPAN class="punctuation token">(</SPAN>func<SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="keyword token">def</SPAN> <SPAN class="token function">wrapper</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="operator token">*</SPAN>args<SPAN class="punctuation token">,</SPAN> <SPAN class="operator token">**</SPAN>kwargs<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">print</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Timing function for... {}"</SPAN><SPAN class="punctuation token">.</SPAN>format<SPAN class="punctuation token">(</SPAN>func<SPAN class="punctuation token">.</SPAN>__name__<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; t0 <SPAN class="operator token">=</SPAN> time<SPAN class="punctuation token">.</SPAN>perf_counter<SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="comment token"># start time</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; result <SPAN class="operator token">=</SPAN> func<SPAN class="punctuation token">(</SPAN><SPAN class="operator token">*</SPAN>args<SPAN class="punctuation token">,</SPAN> <SPAN class="operator token">**</SPAN>kwargs<SPAN class="punctuation token">)</SPAN>&nbsp; <SPAN class="comment token"># ... run the function ...</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; t1 <SPAN class="operator token">=</SPAN> time<SPAN class="punctuation token">.</SPAN>perf_counter<SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="comment token"># end time</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">print</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Results for... {}"</SPAN><SPAN class="punctuation token">.</SPAN>format<SPAN class="punctuation token">(</SPAN>func<SPAN class="punctuation token">.</SPAN>__name__<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">print</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="string token">"&nbsp; time taken ...{:12.9e} sec."</SPAN><SPAN class="punctuation token">.</SPAN>format<SPAN class="punctuation token">(</SPAN>t1<SPAN class="operator token">-</SPAN>t0<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="comment token">#print("\n {}".format(result))&nbsp; # print within wrapper</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">return</SPAN> result&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="comment token"># return result</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="keyword token">return</SPAN> wrapperdelta_time <SPAN class="keyword token">def</SPAN> <SPAN class="token function">array_mean</SPAN><SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="string token">"""change the func"""</SPAN> &nbsp;&nbsp;&nbsp; a_mean <SPAN class="operator token">=</SPAN> a<SPAN class="punctuation token">.</SPAN>mean<SPAN class="punctuation token">(</SPAN>axis<SPAN class="operator token">=</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="number token">2</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">3</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="keyword token">return</SPAN> None <SPAN class="keyword token">def</SPAN> <SPAN class="token function">time_test</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">:</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="string token">"""time test for block and sliding raster"""</SPAN> &nbsp;&nbsp;&nbsp; N <SPAN class="operator token">=</SPAN> <SPAN class="punctuation token">[</SPAN><SPAN class="number token">100</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">500</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">1000</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">2000</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">3000</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">4000</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">5000</SPAN><SPAN class="punctuation token">]</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="keyword token">for</SPAN> n <SPAN class="keyword token">in</SPAN> N<SPAN class="punctuation token">:</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; a <SPAN class="operator token">=</SPAN> np<SPAN class="punctuation token">.</SPAN>arange<SPAN class="punctuation token">(</SPAN>n<SPAN class="operator token">*</SPAN>n<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">.</SPAN>reshape<SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">(</SPAN>n<SPAN class="punctuation token">,</SPAN> n<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="comment token">#a0 = stride(a, block=(3, 3))&nbsp; # uncomment this or below</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; a0 <SPAN class="operator token">=</SPAN> block<SPAN class="punctuation token">(</SPAN>a<SPAN class="punctuation token">,</SPAN> block<SPAN class="operator token">=</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="number token">3</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">3</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">print</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="string token">"\nArray size... {0}x{0}"</SPAN><SPAN class="punctuation token">.</SPAN>format<SPAN class="punctuation token">(</SPAN>n<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; a_stat <SPAN class="operator token">=</SPAN> array_mean<SPAN class="punctuation token">(</SPAN>a0<SPAN class="punctuation token">)</SPAN>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="comment token"># time function</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="keyword token">return</SPAN> None ‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN> main section <SPAN class="keyword token">if</SPAN> __name__<SPAN class="operator token">==</SPAN><SPAN class="string token">"__main__"</SPAN><SPAN class="punctuation token">:</SPAN> &nbsp;&nbsp;&nbsp; <SPAN class="string token">"""comparison between block and slide view"""</SPAN> &nbsp;&nbsp;&nbsp; prn<SPAN class="operator token">=</SPAN><SPAN class="token boolean">False</SPAN> &nbsp;&nbsp;&nbsp; time_test<SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN> <SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>
Description: This code does...timing  examples for sliding and block mean Timing results    sliding mean                block mean array size   total time    total time (seconds) 1000x1000   3.85e-02      4.65...e-03 2000x2000   1.51e-01      1.75...e-02  3000x3000   3.41e-01      3.86...e-02  4000x4000   6.37e-01      7.20...e-02  5000x5000   9.46e-01      1.04...e-01 The slowest is obviously the sliding function since it does 9 samples for ever 1 that block does since I used a 3x3 window...I think...it is the easy stuff that confuses.  Enjoy and study the code  and its origins should you be interested.  I should note that the whole area of sliding implementation has been quite the area of investigation.  The implementation that I presented here is one that I chose to use because I liked it.  It may not be the fastest or the bestest... but I don't care...if it takes less than a sip of coffee, it is good enough for me.

That's all for now....