How can I extract each value of a column from a Feature Collection and append it to a new list in Google Earth Engine?

Getting Data Out: Grabbing Column Values as a List in Google Earth Engine

Google Earth Engine (GEE) – it’s a powerhouse. Think of it as a giant, cloud-based workshop packed with satellite imagery and all the tools you need to play with it. One of the things you’ll often want to do is pull specific bits of information out of a FeatureCollection. Imagine you have a spreadsheet of geographic data, and you just want one particular column – that’s what we’re talking about. Specifically, how do you grab all those values from a column (what GEE calls a “property”) and stuff them into a list so you can actually use them? Let’s break it down.

FeatureCollections and Their Innards: Properties

First, a quick recap. A FeatureCollection in GEE is basically a collection of geographic “things” – Features. Each Feature could be anything: a country, a patch of forest, a weather station. And each Feature has a bunch of characteristics attached to it, like labels on a file folder. These are the “properties”: key-value pairs that describe the Feature. Think of it like this: if your Feature is a car, the properties might be “color,” “make,” and “model.”

The Magic Trick: aggregate_array()

Okay, here’s the slickest way to do this: use the aggregate_array() method. Seriously, this is the tool for the job. It’s clean, it’s efficient, and it’ll save you headaches.

Here’s the recipe:

Let’s see it in action:

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