How to extract a property value from a property dictionary object

Question

The aim of this script is to get the precipitation values from a filtered collection and assign them to a precipitation property called "precipitationCal".

After some masking I have a case of nested property called 'precipitationCal' which is actually a dictionary object itself. The following histogram reducer produces two dictionary values, one which is masked, one which is not. If a masked value exists (key is '1'), I need to extract the value. If it doesn't exist (key is '0'), I can use that value. Finally I need to assign either of those values to a renamed property called 'precipitationCal'.

At the moment I get the error "Cannot read property 'if' of undefined". However, the key returns a value if the function is applied to the first image. Any help would be much appreciated.

var geometry = ee.Geometry.MultiPolygon(
    [[[[-39.40378, -16.86954],
       [-39.40378, -16.88301],
       [-39.39863, -16.88301],
       [-39.39863, -16.86954]]],
     [[[-39.37288, -16.87414],
       [-39.37288, -16.88859],
       [-39.36430, -16.88859],
       [-39.36430, -16.87414]]],
     [[[-39.34198, -16.86625],
       [-39.34198, -16.87348],
       [-39.33409, -16.87348],
       [-39.33409, -16.86625]]]], null, false);

var START_DATE = '2020-01-01',
END_DATE = '2020-02-01'

var raincol = ee.ImageCollection('NASA/GPM_L3/IMERG_V06')
  .filterDate(START_DATE, END_DATE)

raincol = raincol.select('precipitationCal')

//function to remove masked images
var filter_masked = function(img) {
// unmask each image in the collection
var unmasked = img.unmask(-999).eq(-999);
// reduce histogram on each image and set  keys as properties (key '1' will be masked pixels)
var rR = unmasked.reduceRegion({
                          reducer: ee.Reducer.frequencyHistogram(),
                          geometry: geometry,
                          scale: 100,
                          bestEffort: true
                          });
var newProperty = ee.Dictionary(rR.get('precipitationCal'));
return img.set(newProperty)}

// apply the reducer mask                
var raincol = raincol.map(filter_masked)

//filter precip collection to eliminate masked pixels
var raincol = ee.ImageCollection(raincol).filter(ee.Filter.notNull(['1']).not())

//rename precip property 
raincol = raincol.map(function(image) {
                var precipdict = ee.Dictionary(image.get('precipitationCal'))
                    return ee.Algorithm.if(precipdict.contains('1')===true, 
                    image.set('precipitationCal', precipdict.get('1')),
                    image.set('precipitationCal', precipdict.get('0'))
                    )
              })

Answer 1

It's ee.Algorithms.If not ee.Algorithm.if