topic Re: Linear trend has to pass through the origin in Python Questions https://community.esri.com/t5/python-questions/linear-trend-has-to-pass-through-the-origin/m-p/235409#M18288 <HTML><HEAD></HEAD><BODY><SPAN>You can force a linear regression to pass through the origin of coordinates. The best way I have found so far it is to convert the raster to a numpy array, move the coordinate system so my origin of coordinates is the point I want to pass through, create a least square model using numpy.linalg.lstsq where Z = aX + bY + c and c = 0, and then use the model to create the raster.</SPAN><BR /><SPAN>I'll let you know if it works.</SPAN></BODY></HTML> Wed, 15 Aug 2012 19:55:43 GMT JoseLuis_Serrano 2012-08-15T19:55:43Z Linear trend has to pass through the origin https://community.esri.com/t5/python-questions/linear-trend-has-to-pass-through-the-origin/m-p/235407#M18286 <HTML><HEAD></HEAD><BODY><SPAN>Hi - I need to interpolate a linear trend surface through a really big number of points but with the condition that the surface has to pass exactly through one of them, like the origin point.</SPAN><BR /><SPAN>I couldn't find any option for that in the trend tool so I though about creating a lot of points really close to the origin point to force the trend but since I already have so many points I get an out of memory error. </SPAN><BR /><SPAN>Does someone know if there is another way of doing this? I am using python to perform this analysis so I though about converting the points to a numpy array but so far I haven't found anything in numpy to calculate the trend.</SPAN><BR /><SPAN>Thanks a lot for your help!</SPAN><BR /><BR /><SPAN>Jose Luis Serrano</SPAN><BR /><SPAN>GIS Programmer/Analyst</SPAN></BODY></HTML> Tue, 14 Aug 2012 17:44:20 GMT https://community.esri.com/t5/python-questions/linear-trend-has-to-pass-through-the-origin/m-p/235407#M18286 JoseLuis_Serrano 2012-08-14T17:44:20Z Re: Linear trend has to pass through the origin https://community.esri.com/t5/python-questions/linear-trend-has-to-pass-through-the-origin/m-p/235408#M18287 <HTML><HEAD></HEAD><BODY><SPAN>I think that almost by definition a trend surface is never going to pass through your data points because it uses a least-squares regression to accomplish this, so a different interpolation method might be needed if this is a requirement - for instance the spline techniques force your interpolated surface through the original data points.</SPAN></BODY></HTML> Wed, 15 Aug 2012 11:08:10 GMT https://community.esri.com/t5/python-questions/linear-trend-has-to-pass-through-the-origin/m-p/235408#M18287 ChristopherThompson 2012-08-15T11:08:10Z Re: Linear trend has to pass through the origin https://community.esri.com/t5/python-questions/linear-trend-has-to-pass-through-the-origin/m-p/235409#M18288 <HTML><HEAD></HEAD><BODY><SPAN>You can force a linear regression to pass through the origin of coordinates. The best way I have found so far it is to convert the raster to a numpy array, move the coordinate system so my origin of coordinates is the point I want to pass through, create a least square model using numpy.linalg.lstsq where Z = aX + bY + c and c = 0, and then use the model to create the raster.</SPAN><BR /><SPAN>I'll let you know if it works.</SPAN></BODY></HTML> Wed, 15 Aug 2012 19:55:43 GMT https://community.esri.com/t5/python-questions/linear-trend-has-to-pass-through-the-origin/m-p/235409#M18288 JoseLuis_Serrano 2012-08-15T19:55:43Z Re: Linear trend has to pass through the origin https://community.esri.com/t5/python-questions/linear-trend-has-to-pass-through-the-origin/m-p/235410#M18289 <HTML><HEAD></HEAD><BODY><SPAN>Please do, the math side of this certainly isn't my strong point so I'll be interested to see the results and what you accomplish.</SPAN></BODY></HTML> Thu, 16 Aug 2012 10:20:35 GMT https://community.esri.com/t5/python-questions/linear-trend-has-to-pass-through-the-origin/m-p/235410#M18289 ChristopherThompson 2012-08-16T10:20:35Z