Extract data from WeatherData as a list of associations

Question

Given weather data for 2013 and 2014 as follows:

t = 
  QuantityMagnitude[
    WeatherData["California", "MeanTemperature", {{2013, 1, 1}, {2014, 1, 1}, "Day"}] 
    "Values"]];

how can I get the average temperature for each day during 2 years as a list of associations, for example:

January 1 -> 12
 ...
 December 31 -> -20

Thijs · Accepted Answer · 2014-08-13 14:40:38Z

6

For me your command doesn't run. I run:

t = 
  QuantityMagnitude[
    WeatherData[
      "California", 
      "MeanTemperature", 
      {{2013, 1, 1}, {2014, 1, 1}, "Day"}
    ]["Values"]];

This contains all temperature quantities.

A list of dates in your period is easily constructed by

DateRange[DateObject[{2013, 1, 1}], DateObject[{2014, 1, 1}]]

so the association array you're looking for can be obtained from

AssociationThread[
    DateRange[DateObject[{2013, 1, 1}], DateObject[{2014, 1, 1}]] -> t
];

edit

In fact, a neater way to achieve this is:

t = WeatherData["California", "MeanTemperature", {{2013, 1, 1}, {2014, 1, 1}, "Day"}];
Association[Rule @@@ MapAt[DateObject, t["Path"], {All, 1}]]

answered Aug 13 '14 at 13:09

Thijs

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$\begingroup$ Thanks for the answer, but what if one of the years has February 29, how can that be considered for the calculation? $\endgroup$ – Mike Aug 13 '14 at 13:18
$\begingroup$ If the year is a leap year, like 2012, February 29 will be included in DateRange[{2012, 1, 1}, {2012, 12, 31}] automatically. Does that answer your question? $\endgroup$ – Thijs Aug 13 '14 at 13:22
$\begingroup$ Actually no, can I explain the question to you via pm? $\endgroup$ – Mike Aug 13 '14 at 13:24
$\begingroup$ Sure, but I don't know how that works :p $\endgroup$ – Thijs Aug 13 '14 at 13:27
1

$\begingroup$ You can create your own chat room here (Mike might need >10 rep to be able to participate). But @Mike if there is a problem with this answer you should make an effort to explain that here so that future visitors can see it. Welcome to MMA.SE. $\endgroup$ – C. E. Aug 13 '14 at 14:36

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