Eo-Learn Bandwise Median & Percentiles over Time

Hey there,

I am currently playing around with the excellent eo-learn library and I am wondering if there is any EOTask or workflow that extracts bandwise mean and percentile values over the entire timeperiod?

I found MapFeatureTask, but I am struggling with accessing the single bands from my data set inside the function. So what I am currently doing is something like a nested loop in which I loop over all bands first and execute the workflow from new for each patch. Is this the way to go? Or how would you go on about this?

BAND_NAMES = ["B02","B03,"B04","B05","B06"]



#loop over band bands, and define workflow from new for each band

for b in range(len(BAND_NAMES)-1):



    print(BAND_NAMES[b])

    #extract band from my S2 Band Stack

    move_band = ExtractBandsTask((FeatureType.DATA, 'S2_L2A_BANDS'),

                                 (FeatureType.DATA, BAND_NAMES[b]),

                                 [b])

    #calculate mean

    calc_mean = MapFeatureTask((FeatureType.DATA, BAND_NAMES[b]),  # input features

                               (FeatureType.DATA_TIMELESS, '{}_mean'.format(BAND_NAMES[b])),  # output feature

                               np.mean,  # a function to apply to each feature

                               axis=0)  # function's kwargs



    #remove extracted temp. band again

    remove_band = RemoveFeature((FeatureType.DATA, BAND_NAMES[b]))



    # define the workflow

    workflow = LinearWorkflow(load,

                              move_band,

                              calc_mean,

                              remove_band,

                              save)



    for idx, patch_name in enumerate(patch_list):

            print(patch_name)



            extra_param = {load: {'eopatch_folder': patch_name},

                           save: {'eopatch_folder': patch_name}}



            workflow.execute(extra_param)

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Hi @siklar,

Your approach of extracting mean values for each band seems to be ok. However, I have a couple of suggestions for improvements:

Instead of creating and running a separate linear workflow for each band you can have one workflow with multiple tasks that extract bands. You can even chain these tasks one after another. The advantage of having a single workflow is that you save and load data only once.

Your task that calculates mean values also works on all bands together. Therefore you can switch the order with the ExtractBandsTask. This way you’ll first have a single task that calculates mean and afterward, you have multiple ExtractBandsTask tasks, one for each band.

Thank you for quick response, @maleksandrov! 🥳