Re: WeatherData - many properties unavailable?
- To: mathgroup at smc.vnet.net
- Subject: [mg96307] Re: WeatherData - many properties unavailable?
- From: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>
- Date: Wed, 11 Feb 2009 05:21:07 -0500 (EST)
- References: <gmrm7r$9pd$1@smc.vnet.net>
Hi Jason,
I've also noted this behaviour. I assume this has something to do with
WeatherData trying to give you the *current* values if you don't
provide a date/time argument. Some stations do not provide an hourly
measurement online, but, for instance, report once every four hours.
If the time of the last report is too far from now, WeatherData
reports it as Missing["NotAvailable"].
Adding a date/time argument increases the response considerably:
Map[WeatherData[#, "Visibility", {2008, 2, 10}, TimeZone -> 6] &,
WeatherData[{"New York", 20}]]
Note that some stations with a low update rate will publish hourly
data a couple of days after the fact. So, historic data may be finer
sampled than current data.
Cheers -- Sjoerd
On Feb 10, 12:51 pm, Jason Evans <ja... at bluejalapeno.com> wrote:
> Hello,
>
> I am interested in the WeatherData function, but it appears that a lot
> of data is unavailable. For example, for the 20 weather stations
> closest to "New York" (where I live), Visibility, CloudCoverFraction,
> and PrecipitationRate are "Missing[NotAvailable]". I understand that
> not all properties are always available, but these seem to be pretty
> basic, important properties, and this information *is* available if
> you go to websites for the individual weather stations.
>
> Example code to show the property for the 20 stations closest to New
> York would be:
>
> Map[WeatherData[#, "Visibility"] &, WeatherData[{"New York", 20}]]
>
> I also tried this for other large cities, such as Dallas and Chicago,
> with similar results.
>
> Am I doing something wrong, or is a lot of the data just not available
> through Mathematica?
>
> Thanks,
>
> Jason