[R-sig-Geo] Trend significance bfast

[Bacou, Melanie]

Note that NDVI trend decomposition is also available in package 
greenbrown by Matthias Forkel :
http://greenbrown.r-forge.r-project.org/trends.php


On 7/8/2016 1:58 AM, Bacou, Melanie wrote:
> Sorry, sent that too fast. `seasonal()` is defined in the bfast 
> package here:
> https://github.com/cran/bfast/blob/master/R/seasonal.R
>
> --Mel.
>
>
> On 7/8/2016 1:51 AM, Bacou, Melanie wrote:
>> Guillaume,
>> See 
>> https://www.rforge.net/doc/packages/hydroTSM/seasonalfunction.html 
>> for the `zoo:seasonal()` function. In general just look into the 
>> package's NAMESPACE to see which libraries are imported.
>>
>> --Mel.
>>
>>
>> On 7/7/2016 5:10 PM, Guillaume Clair wrote:
>>> Hi,
>>>
>>> I'm using the function (and package) bfast to work on some NDVI 
>>> MODIS datas
>>> in Kenya.
>>>
>>> I modified the original function in order to extract directly the only
>>> datas that I need, i.e. the trend component (Tt) and the dates of
>>> breakpoints in trend (bp.Vt)
>>>
>>> I'd like to process the results in order to get the slopes (this I 
>>> managed
>>> since it is easy math), and also very importantly I would like to 
>>> get some
>>> significance of the trend, like it is generally possible to get with 
>>> the
>>> parameter ANOVA = T in the plot.bfast function. We can see an 
>>> exemple of
>>> the result HERE <http://fr.tinypic.com/r/doo3l0/9>.
>>>
>>> I have two separate questions, the first one is critical, the second is
>>> more out of curiosity in order to understand something that I don't
>>> understand for now :
>>>
>>> - in the source code of the function plot.bfast (
>>> https://github.com/cran/bfast/blob/d8d853096d628b62251c6d302319fa95c14e0206/R/plot.bfast.R), 
>>>
>>> the lines 36 and 37 are processing the ANOVA parameter. Could someone
>>> explain me what is the seasonal() function which is used, and which I
>>> cannot find anywhere ? What I would like to do is to adapt/create my 
>>> own
>>> script in order to get the same information directly from my own 
>>> processed
>>> datas (only Tt and bp.Vt), since I cannot process it again by lack of
>>> computing power. I hope the absence of the ci.Vt won't be a problem...
>>>
>>> - does someone know why sometime the ANOVA parameter doesn't work ? And
>>> instead return an error
>>>
>>> Error in out$bp.Wt$datatsp : $ operator is invalid for atomic vectors
>>>
>>> with a plotting just partially made...
>>>
>>> Thank you all for your attention.
>>>
>>> Best regards.
>>>
>>> Guillaume
>>>
>>> R Version : 3.3.1
>>>
>>> Platform : x86_64-w64-mingw32
>>>
>>>     [[alternative HTML version deleted]]
>>>
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>>
>