[Qgis-user] Automating creation of county distribution maps

[Jésahel Benoist]

Great, thanks for sharing !

Le sam. 12 mars 2022 à 10:43, Bernd Vogelgesang <bernd.vogelgesang at gmx.de>
a écrit :

> Hi Mike and list,
>
> I took the challenge and so far succeeded at the very moment. Mike sent me
> a (not so clean list) of species and counties.
>
> My idea was to produce an atlas. (Actually, it should be made by a report,
> but since those are a bit quirky still, I went the pure atlas way)
>
> It's a bit hacky, a more straightforward way would be nice.
>
> - cleaning the data and importing them (table species/county, county
> polygons)
>
> - create table of individual species (toolbox "Delete duplicates by
> attribute") -> 101 unique species
>
> - Setting up a relation between county layer and species/county-table on
> the county name
>
> - new text field in county layer "species" :
>
> relation_aggregate('name_of_relation', 'concatenate', "species_names",
> ',')
>
> this creates a comma-separated list of species for each county polygon
>
> Prepare Atlas
>
> Coverage layer: (fake coverage, as it does not move)
>
> - create bounding box of the county-layer (Extract layer extent)
>
> - take list of individual species and add the geometry: retrieved the wkt
> of the extent in the field calculator -> "Geometry by expression":
> geom_from_wkt('Polygon ((355937 4117435, 782844 4117435, 782844 4498773,
> 355937 4498773, 355937 4117435)')
>
> -> 101 extents with species name as atlas coverage
>
> - create new map layout
>
> - Activating atlas, setting species name-field as page name
>
> - duplication of the county-layer and setting up a rule based style:
>
> visible: array_contains( string_to_array( "species_names",','),
> @atlas_pagename)
>
> invisible: else
>
> this query will look for the pagename (= species name) in the array of
> species names in the county polygons, and if the name is in, then the
> polygon is shown in grey, alse transparent.
>
> add text field @atlas_pagename
>
> set atlas output filename to @atlas_pagename
>
> Export atlas as images
>
> DONE
>
> Question: is there a way to aggregate the species per county without
> setting up that relation beforehand? This is an extra step which would be
> nice if it could be circumvented by some cool function.
>
> Any ideas or comments?
>
> Am 12.03.22 um 10:04 schrieb Jésahel Benoist via Qgis-user:
>
> Hello Mike,
>
> I tried to follow your question and the most I read the less I understand !
> Could you simply explain what you want to see, what action the user have
> to do and what he gets?
> For this, try to give input data and what will link them : plants (table
> with plant name and states distribution?), states (geometric data with
> states names?), columns to link...
> The good point is that I'm sure QGIS can do this. But nobody will engage
> work if objective isn't precise enough.
>
> Regards,
>
> J. B.
>
>
> Le ven. 11 mars 2022 à 21:50, Mike Breiding - Morgantown WV via Qgis-user <
> qgis-user at lists.osgeo.org> a écrit :
>
>> I had the range USA range map in the screen shot and have since updated
>> it.  https://photos.app.goo.gl/ktn5quT6s6SRwrzBA
>> WV-Mike
>> ------------
>> On 3/10/2022 11:04 AM, chris hermansen wrote:
>> > Perhaps others are better understanding how you want to visualize the
>> > distributions, but what I get from your description is that if you have
>> > 100 (or 2500) species then you will have 100 (or 2500) maps, which
>> > sounds unwieldy to me.
>>
>> I neglected to mention the use for the distribution maps.
>> They will be used in a print brochure.
>> A page mock up can be seen here:
>> https://photos.app.goo.gl/ktn5quT6s6SRwrzBA
>>
>> The USA distribution map in the mock up was made in Qgis using the
>> information from:
>> https://plants.usda.gov/home/plantProfile?symbol=BODI2
>>
>> This is interactive and will display down to the state and county level.
>> However, they are not up to date at the state/county level. If they were
>> I would simply make a screen shot and that would be the end of it.
>>
>> The state distribution map used in the mock up was made using Qgis based
>> on data from the West Virginia University Herbarium which has the most
>> up to date information on distribution.
>>
>> WV-Mike
>>
>>
>>
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