[Qgis-user] ordering an attribute table

[Michael Spencer]

It's a 5km grid of Scotland. I've stuck it on Ubuntu One. Zip file is 54.2
kB, located here: http://ubuntuone.com/5xQiQg5d2Gel1FYYhZDwee

There's no super rush, it's for a blog how to for displaying two raster
values at the same time.

Thanks in advance,
Michael


On 27 September 2013 15:44, Nathan Woodrow <madmanwoo at gmail.com> wrote:

> How big is your layer and could you upload it to somewhere for me, and
> others, to test (note that I'm going to bed now so may not answer until
> tomorrow)
>
> - Nathan
>
>
> On Sat, Sep 28, 2013 at 12:38 AM, Michael Spencer <
> spencer.mike.r at gmail.com> wrote:
>
>> Thanks Nathan,
>>
>> I see where you're coming from, but it's not working. The regex selects
>> all values. I wonder if the problem lies in the data table? The column
>> format is 'real' and I generated the column using the zonal statistics
>> plugin from an underlying raster overlain with a regular grid. Null values
>> seem to have been produced for cells outside the raster, with nan produced
>> where the raster has no data.
>>
>> I recoded the raster output from grass to classify the no data values as
>> -999. How do I go about selecting these? I thought "column" < 0 would work,
>> but this doesn't select anything.
>>
>> Another option could be to use the raster tool and vectorise it,
>> unfortunately this doesn't produce a whole grid as it only outputs integer
>> values and joins some cells together.
>>
>>
>> On 27 September 2013 13:44, Nathan Woodrow <madmanwoo at gmail.com> wrote:
>>
>>> Hey Michael,
>>>
>>> Try this expression using the advanced selection feature:
>>>
>>> regexp_match('column', '\\d*') = 1
>>>
>>> This is using a regex to match column as any number of digits (\\d*).
>>>  If it's not a digit it will return 0 so you want to only select the ones
>>> that = 1.
>>>
>>> - Nathan
>>>
>>>
>>>
>>> On Fri, Sep 27, 2013 at 10:16 PM, Michael Spencer <
>>> spencer.mike.r at gmail.com> wrote:
>>>
>>>> Date: Thu, 26 Sep 2013 18:18:10 +0200
>>>> From: Bernhard Str?bl <bernhard.stroebl at jena.de>
>>>>
>>>>
>>>> Hi,
>>>>
>>>> Am 26.09.2013 18:07, schrieb Michael Spencer:
>>>> > Having a strange problem at the moment.
>>>> >
>>>> > If I open a vector attribute table and click on a column heading to
>>>> sort
>>>> > the column then this doesn't seem to work. The column contains mainly
>>>> > numbers with some NA and some NULL strings.
>>>> >
>>>> > The sort action groups most together most NA and NULL, and orders the
>>>> > numbers, but some strings slip through the gaps and appear where they
>>>> > aren't wanted in the number sequence!
>>>> >
>>>> > I'm working in QGIS 2.0.1 on Ubuntu 12.04.
>>>> >
>>>> > The reason I want to do this is to delete all records that aren't
>>>> > numeric, so if there's a neater way to accomplish this that would be
>>>> great!
>>>>
>>>> A neater way would be to select the records in question and then simply
>>>> delete the selected. Hint select for nulls with
>>>> <code>"my_field" is null</code>
>>>>
>>>> Thanks Bernhard, this was my original choice. Unfortunately I find the
>>>> select tool a total black box and can't get my head around it. Your
>>>> suggestion works for entries with 'null' in, but I can't get a response
>>>> when I want to select 'nan' values. I've tried as:
>>>>
>>>> <"field" is nan>
>>>> <"field" is 'nan'>
>>>> <"field" = 'nan'>
>>>>
>>>> Both with no joy. Is there a crib sheet somewhere with basic options on?
>>>>
>>>> Ta,
>>>> Michael
>>>>
>>>> Bernhard
>>>>
>>>> >
>>>> > Ta,
>>>> > Michael
>>>>
>>>> _______________________________________________
>>>> Qgis-user mailing list
>>>> Qgis-user at lists.osgeo.org
>>>> http://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>
>>>
>>>
>>
>
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