On 03/15/2011 11:47 AM, Tom Dimiduk wrote: > Ah thanks. I am used to the general math/physics convention of x axis > being first. Caught between conventions I guess. Good to know why > things are done differently. > > I am using the mouse click event.xdata and event.ydata as indexes into > an array. From what you say, it looks like I want to use > im[im.shape[1]-y, x] to get the pixel a user clicked on. Is that correct?
Almost--but mpl is using an inverted Y-axis so that the y-coordinate increases downward. Therefore you need only im[round(y), round(x)]. Eric > > Thanks agaian, > Tom > > On 03/15/2011 05:35 PM, Eric Firing wrote: >> On 03/15/2011 10:23 AM, Tom Dimiduk wrote: >>> It appears to me that when imshow tells you that the mouse cursor is at >>> x=50, y=100 >>> >>> That corresponds to array element >>> im[100, 50] >>> >>> Is there a reason imshow does not have x be the first coordinate of the >>> array as I would think of as conventional usage? >> >> That is not conventional usage. Instead, for images, it common for the >> image to correspond to a printout of memory, using the C convention. >> Hence the column index is X, and incrementing the row index yields the >> next line down on the page, thereby corresponding to a decrease in the Y >> coordinate. >> >> Eric >> >>> >>> Tom >> >> ------------------------------------------------------------------------------ >> Colocation vs. Managed Hosting >> A question and answer guide to determining the best fit >> for your organization - today and in the future. >> http://p.sf.net/sfu/internap-sfd2d >> _______________________________________________ >> Matplotlib-users mailing list >> Matplotlib-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/matplotlib-users > > ------------------------------------------------------------------------------ > Colocation vs. Managed Hosting > A question and answer guide to determining the best fit > for your organization - today and in the future. > http://p.sf.net/sfu/internap-sfd2d > _______________________________________________ > Matplotlib-users mailing list > Matplotlib-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-users ------------------------------------------------------------------------------ Colocation vs. Managed Hosting A question and answer guide to determining the best fit for your organization - today and in the future. http://p.sf.net/sfu/internap-sfd2d _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
