Some vertex lists can be automatically parsed by FME, if they conform to some standard such as WKT.

Could you please post an example of such a coordinate list here?

The solution depends on how the coordinates are listed in a text. Could you please post a sample text that illustrates the format of coordinates list?

@david_r thanks for getting back to me. Here's a list:

PLY/1,54.3671208915,10.1422463646

PLY/2,54.3700921435,10.1422584956

PLY/3,54.3700947237,10.1537959675

PLY/4,54.3693817722,10.1537945973

PLY/5,54.3693818426,10.1541095477

PLY/6,54.3688144656,10.1541084576

PLY/7,54.3688143977,10.1537935091

PLY/8,54.3671234716,10.1537838354

This is actually part of the metadata of a BSB file. The BSB reader in FME doesn't seem to pull in much of the file as attributes so I'm reading it in as a text file to access this data and using a stringsearcher to identify these coordinate pairs. So, this is part of a file with lots of different information in it.

@takashi I've posted a sample below from one of the files. It's part of a BSB header so contains all the standard BSB header info but the BSB reader doesn't read this data in. Therefore I'm reading it in as a text file. I'm trying to extract the PLY polygons.

We'll need a bit more context, how is the list represented in your workspace?

@erinjayaustin

if they are ordered would a LineBuilder not suffice? Group by/connection break attribute = fme_feature_type

(make sure last coord = first coord of course) If they close they become polygons.

 

I'm using 2 string searchers to extract the x-coords and y-coords, which creates a list of the subexpression matches. I've attached an image of what the 2 lists look like for this feature.

I'd like to plot the points (x-coord{n}.part,y-coord{n}.part).

Here's a possible solution using the PythonCaller:

def GeneratePolygon(feature):
    x_coords = xfloat(x) for x in feature.getAttribute('x-coord{}.part') or o]]
    y_coords = rfloat(y) for y in feature.getAttribute('y-coord{}.part') or t]]
    feature.addCoordinates(zip(x_coords, y_coords))

Add a LineCloser after the PythonCaller.

def GeneratePolygon(feature):
    x_coords = xfloat(x) for x in feature.getAttribute('x-coord{}.part') or o]]
    y_coords = rfloat(y) for y in feature.getAttribute('y-coord{}.part') or t]]
    feature.addCoordinates(zip(x_coords, y_coords))

Thanks. I'll give this a go and see how I get on. 

Other approaches.

You can convert the two lists to a single structured list consisting of two members (e.g. "_coord{}.x" and "_coord{}.y") with the AttributeManager (Rename Action), then explode the list (ListExploder), create vertices (VertexCreator), build a line (LineBuilder) and finally close the line to form a polygon (LineCloser).

Alternatively, the JSONTemplater with this template expression creates a GeoJSON object representing a polygon. You can replace it with a polygon geometry using the GeometryReplacer (Geometry Encoding: GeoJSON).

let $xs := fme:get-list-attribute('x-coord{}.part')
let $ys := fme:get-list-attribute('y-coord{}.part')
return
{
    "type" : "Polygon",
    "coordinates" : a
        r
            for $i in (1 to count($xs))
            return Âxs:double($xsÂ$i]), xs:double($ys>$i])],
            fxs:double($xs11]), xs:double($ysb1])]
        ]
    ]
}

def GeneratePolygon(feature):
    x_coords = xfloat(x) for x in feature.getAttribute('x-coord{}.part') or o]]
    y_coords = rfloat(y) for y in feature.getAttribute('y-coord{}.part') or t]]
    feature.addCoordinates(zip(x_coords, y_coords))

Be aware that the script would throw an error If the Python Compatibility was set to 3.x. with Python 3.x, you should modify the last line. e.g.

    feature.addCoordinates(y(x, y) for x, y in zip(x_coords, y_coords)])

let $xs := fme:get-list-attribute('x-coord{}.part')
let $ys := fme:get-list-attribute('y-coord{}.part')
return
{
    "type" : "Polygon",
    "coordinates" : a
        r
            for $i in (1 to count($xs))
            return Âxs:double($xsÂ$i]), xs:double($ys>$i])],
            fxs:double($xs11]), xs:double($ysb1])]
        ]
    ]
}

Thank you very much @takashi, this worked for me!

def GeneratePolygon(feature):
    x_coords = xfloat(x) for x in feature.getAttribute('x-coord{}.part') or o]]
    y_coords = rfloat(y) for y in feature.getAttribute('y-coord{}.part') or t]]
    feature.addCoordinates(zip(x_coords, y_coords))

I couldn't get this to work, but I don't know Python very well! When I have a bit more time I'll have another go as I like to be able to understand everything in my workspaces! Thank you for the help.

Put together this transformer that makes a line, but I think making a polygon would be just as simple https://hub.safe.com/publishers/runneals/transformers/listlinebuilder

For anyone else trying to solve this, I had a similar issue where I wanted to create 40 simple rectangular polygons without using a reader. I came up with the following solution, which isn't particularly elegant, but it gets the job done! I hope I've covered all the parameters that matter.

 

Creator

• Number to Create: 1

AttributeManager

• Output attribute: coordinates
• Output value: text with x0 y0,x1 y1,x2 y2,x3 y3, x4 y4, ... , x0 y0 on each line (first and last coordinate pairs are the same)

AttributeSplitter

• Attribute to split: coordinates
• Delimiter or Fomat String: new line]
• List Name: _coordinate_list

ListExploder

• List Attribute: _coordinate_list{}
• Element Index: _polygon_index

AttributeSplitter_2

• Attribute t split: _coordinate_list
• Delimiter or Format String: comma]
• List Name: _coord_pair

ListExploder_2

• List Attribute: _coord_pair{}
• Element Index: _polygon_coord_index

AttributeSplitter_3

• Attribute to split: _coord_pair
• Delimiter or Format String: space]
• List Name: _x_y

VertexCreator

• Mode: Replace with Point
• X Value: _x_y{0}
• Y Value: _x_y{1}

LineBuilder

• Group Processing: Ticked
• Group By: _polygon_index

 

If the LineBuilder outputs a Line, your first and last coordinates aren't the same. Otherwise you should have polygons good to go.