[Qgis-user] [QGIS-Developer] New QGIS Date/Time Tools Plugin

[C Hamilton]

Thanks Jeroen,

Here is a link to the timezone geopackage.

https://drive.google.com/file/d/1IS_bExc5M2IhadK9hzE012oorvV3IbBp/view?usp=sharing

You could also use the shapefile from

https://github.com/evansiroky/timezone-boundary-builder/releases/tag/2020d

I am using the version with oceans. I suspect that the shapefile may be
slightly faster than the gpkg, but I haven't tested it yet.

Here is the gpkg of 10,000 random points.

https://drive.google.com/file/d/1Vz0ho8nQ9rxG6YUG_JebyVygBkjMFsGr/view?usp=sharing

Here is a short script that you can run in the QGIS python console to time
how long it takes to search the timezone for each of the 10,000 points.

https://drive.google.com/file/d/1VMBs6AdvdvWOI_S9XvEaDm3oVyr_vHNv/view?usp=sharing

You will either need to pip install the timezonefinder library or install
the datetimetools-3.0.1.zip release which will make the QGIS python console
aware of the library.

https://github.com/NationalSecurityAgency/qgis-datetimetools-plugin/releases/tag/3.0.1

The mention of ArcGIS is simply that we have an ESRI centric environment
and it is difficult to get QGIS accepted so I try to do everything I can to
make QGIS look appealing.

Thanks once again,

Calvin


On Tue, Feb 2, 2021 at 5:23 PM Groene Bij <mail at groenebij.nl> wrote:

> Hi Calvin,
>
>
>
> Could you somehow send me a copy of the 10.000 random point layer and the
> gpkg with the time zones? I would like to try some things, and see if I can
> come up with some suggestions. I could send you an upload link where you
> can upload those files to me, if needed.
>
>
>
> And I am also trying to understand the issue at stake here. You keep
> referring to ArcGIS. Does ArcGIS has a similar tool incorporated In its
> software, including the data?
>
>
>
> And is it necessary to use this tool offline? If so, a database / data
> file is needed anyway. Than the question is, should it be part of the tool,
> or should you be able to download the data when needed (or better,
> beforehand). Benefit of downloading the data separately could be more up to
> date time zone information.
>
>
>
> Kind regards,
>
> Jeroen Hovens
>
>
>
>
>
> *Van:* Qgis-user <qgis-user-bounces at lists.osgeo.org> *Namens *C Hamilton
> *Verzonden:* dinsdag 2 februari 2021 19:40
> *Aan:* Nyall Dawson <nyall.dawson at gmail.com>
> *CC:* QGIS Users <qgis-user at lists.osgeo.org>; Tim Sutton <tim at kartoza.com>;
> qgis-developer <qgis-developer at lists.osgeo.org>
> *Onderwerp:* Re: [Qgis-user] [QGIS-Developer] New QGIS Date/Time Tools
> Plugin
>
>
>
> I created a layer of 10,000 random points. Using timezonefinder to look up
> each point took 44 seconds. I tried using *Vector->Geoprocessing
> Tools->Intersection...* to find the time zones for each of the points and
> it took over 4 minutes.
>
>
>
> Is there a better way to locate which polygon a point is in? 4 minutes is
> not good. Perhaps the intersection algorithm is not the way to go, but I am
> not sure what is. I can't imagine that iterating through each point and
> then iterating through each polygon until an intersection match is found is
> going to be overlay efficient, but I will try it. Is there a better way?
>
>
>
> Thanks,
>
>
>
> Calvin
>
>
>
>
>
> > I wonder what the difference in time would be to use a gpkg and QGIS
> point in polygon look up vs timezonefinder lookup. Will it be faster or
> slower? I'm not sure without testing. What are your thoughts? I would
> choose the faster of the two.
>
> I'd certainly hope a dedicated GIS application can do this faster than
> a random Python library :D
>
> > I just converted the timezone data to a gpkg and its size is 102Mb. The
> data size for timezonefinder using the same data set is 49Mb. The
> optimization in timezonefinder can produce a maximum error of 1cm at the
> equator as they use 32 bit ints for the data. It might actually be better
> to use the gpkg file, but it is double in size. I will investigate using
> the gpkg data.
>
> You may want to try a shapefile too, just in case...!
>
> Nyall
>
>
> >
> > It seems to me that if a plugin requires a certain dataset to function
> then that data should be included with it and not require an additional
> download, but I understand the issues that this could cause so I am not
> sure of the best way forward. For our use it is definitely better to
> include the data with the plugin.
> >
> > I guess what I would like you to take from this conversation is that
> some users have a completely different environment and face different
> challenges then what you do when it comes to dealing with software. I wish
> that it was easier for me to get QGIS acceptance in our workforce but
> ArcGIS still rules.
> >
> > Thanks for your ideas and all of the hard work that you do to keep QGIS
> moving forward.
> >
> > I wish you all the very best!
> >
> > Calvin
> >
> >> Given that the size of the python library is almost entirely the size
> >> of the timezone boundaries themselves, have you considered:
> >> - avoiding the library entirely, and insteading using a standard
> >> shapefile/gpkg/... of the boundaries and using QGIS vector layer
> >> methods to determine the timezone for a point
> >> - deferring the download of the boundary spatial data, so that it's
> >> not supplied with the plugin but instead the plugin automatically
> >> downloads it on first launch?
> >>
> >> This would avoid the need for the large size plugin, allowing it to be
> >> supplied via the standard QGIS repo while still providing its full
> >> functionality...
> >>
> >> Nyall
> >>
> >>
>
>
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