Add highlight/query similar features example

[tristen]

cc @mourner @lucaswoj @jfirebaugh for review

[jfirebaugh]

No parens around features.length.

[tristen]

🚢'd 5342aa9

[nitins1]

How do I find the data stored in the source file (mapbox://mapbox.82pkq93d) so I can manipulate the contents differently. For example, select counties in certain states as well, but using "STATES" as the key in the filter argument of the setFilter method doesn't work. Any ideas?

[tristen]

👋 @nitins1 sounds like you probably want querySourceFeatures?

[lbud]

@nitins1 — @tristen is right in that you can use querySourceFeatures to dig into the data added to a GL map.

Alternatively, you can look for that dataset's TileJSON — in this case, at https://api.mapbox.com/v4/mapbox.82pkq93d.json?secure&access_token=<your access token>
which contains this field:

  "vector_layers": [
    {
      "description": "",
      "fields": {
        "COUNTY": "String",
        "FIPS": "Number",
        "median-income": "Number",
        "population": "Number"
      },
      "id": "original",
      "maxzoom": 22,
      "minzoom": 0,
      "source": "mapbox.82pkq93d",
      "source_name": "counties"
    }
  ],

[nitins1]

@tristen @lbud Thank you both for your responses! So I understand that I can use querySourceFeatures to return an array of objects that match a given filter. But after looking into the dataset's tileJSON, it doesn't seem like this data source has any information about states or counties relating to a state. Is there a data source/another walkthrough example with state data?

edit: I think "FIPS" is some sort of code for states? https://gist.github.com/wavded/1250983/bf7c1c08f7b1596ca10822baeb8049d7350b0a4b

edit again: Yep, FIPS corresponds to states and I got it working. I wanted to highlight only the currently selected county. Thank you both for your help!
map.setFilter('counties-highlighted', [ "all", ['==', 'COUNTY', feature.properties.COUNTY], ['==', 'FIPS', feature.properties.FIPS] ]);

one last edit: The FIPS code data that I posted earlier is only half right. Although each state's FIPS code is a two digit number, each county's FIPS property in the dataset starts with those two digits but is a five digit number. In my case, maryland FIPS code is 24 but each county's FIPS property was 24001, 24014, and the like. Baltimore city was an outlier being in the 24500 range with a FIPS code of 24510. I'm not sure how to select a state's worth of counties since the filters don't have any "starts with" type of operators. I had to use in and !in and included each county's FIPS code as a membership filter.