Create Polyline shapefile, adding attributes issue

MapWinGIS
1

Hi, I am reading from a CSV file, using Lat, Long to create a line shapefile (This is done successfully), at the same time, creating fields and adding values from the CSV to the shapefile. The weird thing is that If I hard code the field index and row (or shape) index, I get that value in the shapefile attributes table. But as I pass fieldIndex, r (row index), nothing inserted. The main part of the code is here. Would anybody give me some clue? Or someone can share your code of creating a polyline shapefile and add attributes to it?

I added a test righter after I insert the value, the value is there in debugging, but the resulted attribute table didn’t have it.
object testStatic = sf.CellValue[2, 2];

I am using VS 2015 on Windows 10. MapWinGIS 5.0, doing windows form app.

Thanks a lot in advance!!

Lang

            for (int r = 1; r < lines.Length-1; r++)  //r =0 is the first line which is headers 
            {               
                string[] dataValue = lines[r].Split(',');
                string[] dataValue1 = { };

                sf.Table.EditInsertRow(ref r);
                //MessageBox.Show(dataValue[5]);
                if (r + 1 < lines.Length-1) {
                    dataValue1 = lines[r + 1].Split(',');
                }
                //char[] charsToTrim = { '*', '"', '\'' };

                for (int i = 1; i < columnCount; i++)
                {
                    //MessageBox.Show(headerLabels[i]);
                    headerLabels[i] = headerLabels[i].Replace("\"","");
                    int fieldIndex = sf.Table.get_FieldIndexByName(headerLabels[i]);

                    if (fieldIndex == -1)
                    {
                        //make IRI field a double to get ready for color-coding
                        if (headerLabels[i].Contains("IRI"))
                        {
                            fieldIndex = sf.EditAddField(headerLabels[i], FieldType.DOUBLE_FIELD, 6, 9);
                        }
                        else
                        {
                            fieldIndex = sf.EditAddField(headerLabels[i], FieldType.STRING_FIELD, 0, 30);
                        }
                    }

                    //MessageBox.Show(fieldIndex.ToString()+","+r.ToString() + ","+dataValue[i]);
                    
                    bool b = sf.EditCellValue(fieldIndex, r, dataValue[i]);
                    object test = sf.CellValue[fieldIndex, r];
                    
                    //sf.Table.EditCellValue(fieldIndex, r, dataValue[i].ToString())  
                    bool b1 = sf.EditCellValue(2, 2, dataValue[i]);
                    object testStatic = sf.CellValue[2, 2];
                   
                    sf.EditCellValue(3, 9, dataValue[i]);
                    sf.EditCellValue(4, 5, dataValue[i]);
                    Console.WriteLine($"{b} {fieldIndex} {r} {dataValue[i]} {i}");
                }
               
                Shape shp = new Shape();
                shp.Create(ShpfileType.SHP_POLYLINE);

                if (dataValue1.Length >= 4)
                {
                    x = Convert.ToDouble(dataValue[selectedIndexX]);
                    y = Convert.ToDouble(dataValue[selectedIndexY]);
                    x1 = Convert.ToDouble(dataValue1[selectedIndexX]);
                    y1 = Convert.ToDouble(dataValue1[selectedIndexY]);

                    
                    if (x.ToString() == null || y.ToString() == null)
                    {
                        MessageBox.Show("X or Y value cannot be null!");
                        return;
                    }
                    MapWinGIS.Point pnt = new MapWinGIS.Point();
                    pnt.x = x;
                    pnt.y = y;
                    int index = shp.numPoints;
                    shp.InsertPoint(pnt, ref index);

                    pnt = new MapWinGIS.Point();
                    pnt.x = x1;
                    pnt.y = y1;
                    index = shp.numPoints;
                    shp.InsertPoint(pnt, ref index);

                    index = sf.NumShapes;
                    sf.EditInsertShape(shp, ref index);
                }
            }
2

I can’t see anything obviously wrong in your code.
I normally start with adding the shape and then the attributes.

You ask for the cell value of the third column of the third shape (sf.CellValue[2, 2]). Are you sure you already added those shapes at that moment? You could check the NumShapes and NumFields before using CellValue.

3

Hi pmeems

Thank you for your kind response! I’ll take your suggestion to adding the shape first and see how it goes. when I test the value of sf.CellValue[2,2], I can see it’s there in debug. But you mean though I can see it, but since the shape many not be created yet, thus it only exits in memory during the debugging and is gone after the session, so that I don’t have it in the resulted shapefile?

4

This is how I would do it.
Because I don’t have your CSV-file I’m using another shpaefile to get some valid coordinates:

This is the code:

// First read some coordinates, in this case I read them from another polyline shapefile:
var sfInput = Helper.OpenShapefile(@"sf\SHP_POLYLINE.shp");
var lines = new List<List<Point>>(); // lines is a list of line and each line is a list of point
for (var i = 0; i < sfInput.NumShapes; i++)
{
    var shp = sfInput.Shape[i];
    var line = new List<Point>();
    for (var j = 0; j < shp.numPoints; j++)
    {
        line.Add(shp.Point[j]);
    }
    lines.Add(line);
}

// Create a new shapefile
var sf = new Shapefile();
Assert.IsNotNull(sf, "sf is null");
Assert.IsTrue(sf.CreateNewWithShapeID("", ShpfileType.SHP_POLYLINE), "Cannot create shapefile");

// Create fields:
var keyFieldIndex = sf.EditAddField("key", FieldType.INTEGER_FIELD, 0, 5);
var evenFieldIndex = sf.EditAddField("even", FieldType.BOOLEAN_FIELD, 0, 1);
var dateFieldIndex = sf.EditAddField("date", FieldType.DATE_FIELD, 0, 12);

// Create new lines:
foreach (var line in lines)
{
    var shp = new Shape();
    Assert.IsTrue(shp.Create(sf.ShapefileType));
    foreach (var point in line)
    {
        // Add point to shape:
        shp.AddPoint(point.x, point.y);
    }

    // Add the new shape to the shapefile:
    var shpIndex = sf.EditAddShape(shp);
    // Add some attributes:
    Assert.IsTrue(sf.EditCellValue(keyFieldIndex, shpIndex, shpIndex), "Cannot add key attribute");
    Assert.IsTrue(sf.EditCellValue(evenFieldIndex, shpIndex, shpIndex % 2 == 0), "Cannot add even attribute");
    Assert.IsTrue(sf.EditCellValue(dateFieldIndex, shpIndex, DateTime.Now), "Cannot add date attribute");
}

// Optional: Add projection:
sf.GeoProjection = sfInput.GeoProjection.Clone();

// Now the new shapefile is created, check it and save it:
Assert.IsFalse(sf.HasInvalidShapes(), "sf has invalid shapes");
var fileLocation = Path.Combine(Path.GetTempPath(), "NewShapefile.shp");
Helper.SaveAsShapefile(sf, fileLocation);

And this is the result:

image
image.png928×663 54 KB

The green+red dotted lines are from the new shapefile. The table editor shows the attributes of the 4 lines.

If you attach your CSV-file I can update the code to fit your needs.

These are the basic steps needed:

  1. Create a shapefile
  2. Add some fields
  3. Add 1 or more shapes in a loop
  4. Fill the attributes of that shape within that loop
  5. Save the shapefile
5

Dear pmeems,

Really appreciate it! You showed me a new way to do it. I’ll definitely give it a try and let you know the result.

You used Assert in your code. Will you share that function?

I tried to upload the csv, but being told that new users cannot upload attachment!! Why? So I have to copy it below for you. Or email me, so I can send it to you:
denglang36@yahoo.com. Thanks!

From (ft.) To (ft.) Distance (ft.) GPS Latitude GPS Longitude IRI Average (in/mi)
0+00.0 1+00.0 100 42.0904452 -87.71785224 303.62
1+00.0 2+00.0 100 42.09066704 -87.71763038 131.2
2+00.0 3+00.0 100 42.09086039 -87.71736568 267.52
3+00.0 4+00.0 100 42.09106414 -87.71712586 463.8
4+00.0 5+00.0 100 42.09129138 -87.7169103 234.07
5+00.0 6+00.0 100 42.09150166 -87.71666953 306.37
6+00.0 7+00.0 100 42.09171606 -87.71644683 211.32
7+00.0 8+00.0 100 42.0919315 -87.71621995 326.62
8+00.0 9+00.0 100 42.0921311 -87.71596777 395.28
9+00.0 10+00.0 100 42.09233814 -87.71572284 424.08
10+00.0 11+00.0 100 42.09256371 -87.71550879 386.68
11+00.0 12+00.0 100 42.09278509 -87.71528592 250.14
12+00.0 13+00.0 100 42.09297916 -87.7150244 342.5
13+00.0 14+00.0 100 42.09285975 -87.71470643 344.36
14+00.0 15+00.0 100 42.09270548 -87.71439969 181.8
15+00.0 16+00.0 100 42.09249977 -87.71414631 174.16
16+00.0 17+00.0 100 42.0923244 -87.71385283 350.38
17+00.0 18+00.0 100 42.09216728 -87.71355021 213.26
18+00.0 18+46.3 46.3 42.09197615 -87.71328179 280.86

Lang

6

Hi pmeems,

Problem solved! You are exactly correct: when I write the attributes, the shapes are not created yet! So I just create the shapes before editing attributes and everything works now. Thank you so much!
Also, I see you opened a table for editing shapefile? Will you share code for that?
Plus, how do you do identify? I am using editing table in lieu of identify now.

Lang

7

Assert is just a default C# method to use in unit tests.

The screenshots I made using MapWindow5 (MW5).
This is the desktop GIS that uses MapWinGIS as the mapping engine.

If you need a full working GIS it might be easier to create a plug-in for MW5 and just build your specific code and reuse everything else from MW5.
We have a template plug-in written in C# to help you get started.

8

Hi Pmeems,

Would you please try to use the csv I gave you to create a polyline shapefile? I just figured that the attributes are added correctly but I don’t see any shape. will you try to see if you can create a polyline shapefile? Thanks a lot in advance!

Lang

9

I’ve sent you an e-mail requesting for the CSV-file because the one in the post is unclear to me.
Is every line a point of the polyline and do you expect just 1 polyline?

When you zip your csv you should be able to attach it to your post.