Re: [Qgis-user] calculating progressive value
thank you, it works fine! I didn't update the table and so I didn't see the right values in the y column -- View this message in context: http://osgeo-org.1560.x6.nabble.com/calculating-progressive-value-tp5280693p5281019.html Sent from the Quantum GIS - User mailing list archive at Nabble.com. ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: http://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] calculating progressive value
What exactly did you enter into the query window? The word "table" should be the name of your points layer. On 08/17/2016 12:21 AM, Salvanet wrote: Hi Micha, I apply the query with spatial lite, but the result is "near "table": syntax error". Sorry, but this is the first time I use spatialite in QGS with DB manager, what am I doing wrong? thank you -- View this message in context: http://osgeo-org.1560.x6.nabble.com/calculating-progressive-value-tp5280693p5280982.html Sent from the Quantum GIS - User mailing list archive at Nabble.com. ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: http://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: http://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] calculating progressive value
Hi Micha, I apply the query with spatial lite, but the result is "near "table": syntax error". Sorry, but this is the first time I use spatialite in QGS with DB manager, what am I doing wrong? thank you -- View this message in context: http://osgeo-org.1560.x6.nabble.com/calculating-progressive-value-tp5280693p5280982.html Sent from the Quantum GIS - User mailing list archive at Nabble.com. ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: http://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] calculating progressive value
Salvanet wrote > Hi, I have a Qgis layer with a table with twno columns X and Y. > The X column has a set of values, while in the Y column I have to enter, > using field calculator, for each record the progressive value. Eg : X > column values: a , b , c , d ; Y column values (to be calculated with the > field calculator from Y column): a; a + b; a + b + c; a + b + c + d. > > How can I do this? > > > > > thank you > > ___ > Qgis-user mailing list > Qgis-user@.osgeo > List info: http://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user I can suggest a way to do what (I think) you want if you transfer your table to a database such as Spatialite or PostGIS. But first a caveat: there is no guarantee that the order of rows in a spatial table will stay constant, so adding values progressivley from previous rows might not work as you expect. For example, say you split a feature into two, or add a new feature, then a new row will be added, with some X value which might be "out of order". Having said that warning, suppose you have a table such as: id X Y -- 1 1 0 2 3 0 3 0 0 4 5 0 5 6 0 (Note the id column with sequntial primary keys) A query such as: UPDATE table SET y=(SELECT sum(t.x) FROM table as t WHERE t.id<=table.id); will result in: id X Y --- 1 1 1 2 3 4 3 0 4 4 5 9 5 6 15 HTH -- View this message in context: http://osgeo-org.1560.x6.nabble.com/calculating-progressive-value-tp5280693p5280800.html Sent from the Quantum GIS - User mailing list archive at Nabble.com. ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: http://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] calculating progressive value
Hi Cristine, thank you for the answer, the problem is that X column values are variables -- View this message in context: http://osgeo-org.1560.x6.nabble.com/calculating-progressive-value-tp5280693p5280749.html Sent from the Quantum GIS - User mailing list archive at Nabble.com. ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: http://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] calculating progressive value
Hi, unless the number of combinations is known and limited, using case when function could become a nightmare. QGIS 2.16 provides aggregates functions ( http://qgis.org/fr/site/forusers/visualchangelog216/index.html#feature-aggregate-support-for-expressions) that I think would help to do this but I'm unable to find the right syntax, if ever. Regards, Harrissou 2016-08-14 14:07 GMT+02:00 Christine : > Salvatore Oliveto wrote > > Hi, I have a Qgis layer with a table with twno columns X and Y. > > The X column has a set of values, while in the Y column I have to > enter, > > using field calculator, for each record the progressive value. Eg : X > > column values: a , b , c , d ; Y column values (to be calculated with the > > field calculator from Y column): a; a + b; a + b + c; a + b + c + d. > > Hi Salvatore, > not really sure, if I understood you properly, but you can use a "case when > ... then ... else" condition in field calculator. Please adapt the > following > pattern to your needs: > > CASE > WHEN X = a THEN a > WHEN X = b THEN a+b > WHEN X = c THEN a+b+c > WHEN X = d THEN a+b+c+d > ELSE 'error value' > END > > Hope this helps, > regards, Christine > > > > > > > -- > View this message in context: http://osgeo-org.1560.x6. > nabble.com/calculating-progressive-value-tp5280693p5280699.html > Sent from the Quantum GIS - User mailing list archive at Nabble.com. > ___ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > List info: http://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: http://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] calculating progressive value
Salvatore Oliveto wrote > Hi, I have a Qgis layer with a table with twno columns X and Y. > The X column has a set of values, while in the Y column I have to enter, > using field calculator, for each record the progressive value. Eg : X > column values: a , b , c , d ; Y column values (to be calculated with the > field calculator from Y column): a; a + b; a + b + c; a + b + c + d. Hi Salvatore, not really sure, if I understood you properly, but you can use a "case when ... then ... else" condition in field calculator. Please adapt the following pattern to your needs: CASE WHEN X = a THEN a WHEN X = b THEN a+b WHEN X = c THEN a+b+c WHEN X = d THEN a+b+c+d ELSE 'error value' END Hope this helps, regards, Christine -- View this message in context: http://osgeo-org.1560.x6.nabble.com/calculating-progressive-value-tp5280693p5280699.html Sent from the Quantum GIS - User mailing list archive at Nabble.com. ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: http://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
