[Qgis-user] fields are not updated with calculated field values in QGIS 2.14

[Alexandre Neto]

A dom, 6/03/2016, 21:39, Roy Marsh <roymarsh11 at gmail.com> escreveu:

> Hi Alexandre
> The data is UTM34S, coordinates about [20, -34], which is for the training
> exercise data (S Africa) - the layers created are where they should be
>

Those values, if from south Africa, can't be UTM. UTM are in metres, and we
should expect much higher values. Those are still in degrees.

I converted the shp file using Properties 'Set Layer CRS', from default
> 'WGS 84' to 'EPSG 32734 / WGS 84 / UTM 34S'
>

The explanation is here. Setting the layer CRS don't change it's
coordinates values, it only tells QGIS to consider the values to be in that
new CRS.

To convert the shapefile to a new CRS you need to right-click the layer and
choose save as... And then choose the new CRS.

The data type of the target field is Double, with 5 decimal places
> But then selecting the function $area just creates zero values
>

Because saying QGIS the values were in meters you got sub-meter size
features.

Good luck,

Alexandre Neto

I can't think of anything else to try and would be grateful for suggestions.
> Roy
>
>
> 2016-03-05 23:18 GMT+00:00 Alexandre Neto <senhor.neto at gmail.com>:
>
>> Hi Roy,
>>
>> Are you sure your data is UTM 34 S? How did you convert the data to that
>> crs? What are the approximated coordinates values of your data
>> ?
>>
>> A sáb, 5/03/2016, 20:01, Roy Marsh <roymarsh11 at gmail.com> escreveu:
>>
>>> Hi
>>> As a relative newcomer I have been working through the QGIS 2.14
>>> training manual. Section 4.3.3 explains how to add calculated values using
>>> the Field Calculator.
>>> But when I do this ..(the examples are from 2.8 but the same procedure
>>> seems to apply to 2.14)..  the value stays as 0. It does this whatever
>>> parameters I try. It does this for both 'new field' and 'update field.' It
>>> does this even if layers are reprojected to UTM 34S (so as to show area in
>>> metres, not degrees).
>>> Is this a bug?
>>> Thanks
>>> Roy
>>>
>>>
>>>
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>>
>> --
>> Alexandre Neto
>> ---------------------
>> @AlexNetoGeo
>> http://sigsemgrilhetas.wordpress.com
>> http://gisunchained.wordpress.com
>>
>
> --
Alexandre Neto
---------------------
@AlexNetoGeo
http://sigsemgrilhetas.wordpress.com
http://gisunchained.wordpress.com
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