Skip to main content
Question

How to build a fme Line from json array?

  • June 20, 2017
  • 3 replies
  • 311 views
R
Forum|alt.badge.img

I have a json array which a represents the shortest path between two locations. My question is how could I convert this array to a line in to use it later on LineOnAreaOverlayer transformer.

"geometry": {
          "paths": [
            [
              [
                -13660298.311,
                5735294.6307
              ],
              [
                -13660298.5799,
                5735271.5189
              ],
              [
                -13660196.166000001,
                5735271.5189
              ],
              [
                -13660188.373599999,
                5735271.5189
              ],
              [
                -13660085.9597,
                5735253.980499998
              ],
              [
                -13659999.1305,
                5735056.277500004
              ],
              [
                -13659796.529,
                5735037.145199999
              ],
              [
                -13659799.8686,
                5734917.5691
              ],
              [
                -13659798.7554,
                5734762.919799998
              ],
              [
                -13659800.981800001,
                5734649.724600002
              ],
              [
                -13659671.8512,
                5734649.724600002
              ],
              [
                -13659505.985199999,
                5734581.170500003
              ],
              [
                -13659238.8184,
                5734491.891400002
              ],
              [
                -13659235.478799999,
                5734381.888099998
              ],
              [
                -13659233.2524,
                5734310.147600003
              ],
              [
                -13659232.1392,
                5734182.610299997
              ],
              [
                -13659231.026,
                5734153.9146
              ],
              [
                -13659228.7996,
                5734050.292199999
              ],
              [
                -13659229.9128,
                5733984.931000002
              ],
              [
                -13659231.026,
                5733798.415100001
              ],
              [
                -13659232.1392,
                5733761.750100002
              ],
              [
                -13659200.2391,
                5733761.574100003
              ]
            ]
          ]
        }

This post is closed to further activity.
It may be an old question, an answered question, an implemented idea, or a notification-only post.
Please check post dates before relying on any information in a question or answer.
For follow-up or related questions, please post a new question or idea.
If there is a genuine update to be made, please contact us and request that the post is reopened.

3 replies

redgeographics
Celebrity
Forum|alt.badge.img+62

I think I got it... I've saved your array in to a text file and using a text line reader, set to read the whole file at once, so it ends up as 1 feature with a single attribute. I use a JSONFlattener which turns the JSON into a nested list, then 2 ListExploders to get to the stuff I need, a VertexCreator to make points and a LineBuilder to connect them into a line. Hope this helps.

textline2none.fmw

FME rocks! \m/
takashi
Celebrity
  • takashiCelebrity
  • June 21, 2017

Hi @rrdlpl, although the "paths" array in the sample JSON document contains only a single element (segment = array of coordinates [x, y]), it can also contain two or more segments. Is there a case where a "paths" consists of multiple segments?

If yes, there are at lease three possible geometry types that can be created from the "paths" array, and you will have to decide which one is preferable.

  1. Connect all segments to form a single IFMELine geometry.
  2. Build an IFMEPath geometry consisting of the segments (only if the segments always form a consecutive polyline shape).
  3. Build an IFMEMultiCurve geometry consisting of the segments.

@redgeographics' solution creates an IFMELine geometry. If you need to build IFMEPath or IFMEMultiCurve, some improvement should be done on the workflow.

Why not inspect features with Visual/Data Preview and Feature/Record Information before writing them into a destination dataset?
takashi
Celebrity
  • takashiCelebrity
  • June 21, 2017

I believe that @redgeographics' solution is the regular tactics, but there could also be other ways depending on your preference,

for Pythonists:

0684Q00000ArKm2QAF.png

# PythonCaller Script Example
import fmeobjects, json
def buildLine(feature):
    coords = json.loads(feature.getAttribute('text_line_data'))
    feature.setGeometry(fmeobjects.FMELine([(c[0], c[1]) for c in coords]))

for XML lovers:

0684Q00000ArLCHQA3.png

(: XMLTemplater Template Expression Example:)
declare namespace gml="http://www.opengis.net/gml/3.2";
<gml:LineString><gml:posList>{
for $i in (0 to xs:integer(fme:get-attribute("_element_count")) - 1)
return fme:get-list-attribute(fn:concat("array{", $i, "}.array{}"))
}</gml:posList></gml:LineString>

[Addition] GeoJSON version:

0684Q00000ArLCPQA3.png

{
    "type" : "LineString",
    "coordinates" : fme:get-json-attribute("text_line_data")
}

Which one do you like?

Why not inspect features with Visual/Data Preview and Feature/Record Information before writing them into a destination dataset?

Community Stats

32,180
Posts
122,164
Replies
39,853
Members

Latest FME

Terms & ConditionsCookie settingsAccessibility statement
A product of
Safe Software respectfully acknowledges that we live, learn and work on the traditional and unceded territories of the Kwantlen, Katzie, and Semiahmoo First Nations.