[GIS] “Undefined variable from import” Earth Engine and Python API

google-earth-engineimportpython

I'm writing some code for a GEE Application and I want to calculate the area of pixels in a given area.
I've found this method:


areas = (imNDVI4.multiply(ee.Image.pixelArea()).reduceRegion(reducer = ee.Reducer.sum(), geometry = test2, scale=10))

Unfortunately, I'm unable to run this part because of this error:

Undefined variable from import: …

that pops up both on pixelArea() and Reducer methods.

How could I solve this issue?

P.S. My "earthengine-api" package is already up to date.

Best Answer

I personally solved this issue after an aid from a friend of mine. The problem is not due to Python itself but by its interpreter.

So, if you're using Eclipse follow this procedure: Window > Preferences > PyDev > Editor > Code Analysis > Undefined > Undefined variable from import > Ignore

This is also quite useful if you want to not show those boring warnings from unused imports. The procedure is just the same, only change the selected tab.

Related Solutions

Google Earth Engine – How to Calculate Number of Pixels Inside a Polygon?

The inputs to the count reducer are not weighted. A pixel is either in or out. If it's in, the centroid of the pixel must be in the region. It's out otherwise. The mean is weighted by area, so you get an answer based on the fraction of the pixel intersected by the region.

Edit:

As suggested by Noel, you can use the sum() reducer on the image mask to get both fractional pixels and area. Continuing the OP's example,

var mask = image.select(0).mask().rename('mask');
var area = ee.Image.pixelArea().multiply(mask).rename('area');

var sumDictionarypolygon1 = mask.addBands(area).reduceRegion({
  reducer: ee.Reducer.sum(),
  geometry: polygon1.geometry(),
  scale: 30,
  maxPixels: 1e9
});
print('sum for pol 1 mask, scale=30', sumDictionarypolygon1);

Note that you can get a more accurate area (that matches polygon1.area()) by increasing the scale.

[GIS] get date from image using python API in Google Earth Engine

It is possible the access the date in the following way:

import ee

ee.Initialize()

collection = ee.ImageCollection('LANDSAT/LC08/C01/T1')

date = ee.Date(collection.first().get('system:time_start'))

date_dict = date.getInfo()

print "The number of milliseconds since 1970-01-01T00:00:00Z.: ", date_dict['value']

print "Formatted date", date.format('Y-M-d').getInfo()

Just calling ".getInfo()" on the ee.Date object will give you the number of milliseconds since 1970-01-01 in a Python dictionary.

It is possible to format the date with the ".format" method.

Best Answer

Related Solutions

Google Earth Engine – How to Calculate Number of Pixels Inside a Polygon?

[GIS] get date from image using python API in Google Earth Engine

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