[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
## Re: counting totals in square grids (meshgrid)

**From**: |
Jaroslav Hajek |

**Subject**: |
Re: counting totals in square grids (meshgrid) |

**Date**: |
Mon, 14 Dec 2009 11:27:56 +0100 |

On Mon, Dec 14, 2009 at 11:12 AM, Isak Delberth Davids
<address@hidden> wrote:
>* I see, that last question of mine was really not needed, because value*
>* of grid(i,j) is exactly equal to the number of elements that are in*
>* the i-j-th grid. What more do I want there? My question was unclear*
>* and aboveall, it was unnecessary. Jaroslav, thanks for the assistance!*
>
Good.
>* Now back to improving the efficiency of the lines:*
>* for i = 1:n*
>* for j = 1:n*
>* grid(i,j) = sum (i-1 <= x & x < i & j-1 <= y & y < j);*
>* end*
>* end*
>
>* Do you have a suggestion?*
>
You can do something like this (not tested):
i = floor (x);
j = floor (y);
mask = i > 0 & i <= n & j > 0 & j <= n;
grid = accumarray ([i,j](mask,:), 1, [n, n]);
see "help accumarray"
--
RNDr. Jaroslav Hajek
computing expert & GNU Octave developer
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz

**counting totals in square grids (meshgrid)**, *Isak Delberth Davids*, `2009/12/14`
**Re: counting totals in square grids (meshgrid)**, *Jaroslav Hajek*, `2009/12/14`
**Re: counting totals in square grids (meshgrid)**, *Isak Delberth Davids*, `2009/12/14`
**Re: counting totals in square grids (meshgrid)**, *Jaroslav Hajek*, `2009/12/14`
**Re: counting totals in square grids (meshgrid)**, *Isak Delberth Davids*, `2009/12/14`
**Re: counting totals in square grids (meshgrid)**, *Jaroslav Hajek*, `2009/12/14`
**Re: counting totals in square grids (meshgrid)**, *Isak Delberth Davids*, `2009/12/14`
**Re: counting totals in square grids (meshgrid)**, *Jaroslav Hajek*, `2009/12/14`
**Re: counting totals in square grids (meshgrid)**, *Isak Delberth Davids*, `2009/12/14`
**Re: counting totals in square grids (meshgrid)**,
*Jaroslav Hajek* **<=**
**Re: counting totals in square grids (meshgrid)**, *Isak Delberth Davids*, `2009/12/14`