Wednesday, May 24, 2017

When to use ArcGIS Online to publish geospatial data: CASE STUDY EUROPEAN ENVIRONMENT AGENCY

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ArcGIS Online is a workspace and a web platform for creating and sharing maps. It is possible to upload your data, create a layer or a map, define the extent, set some visualization options, assign permissions to your layer or map, share, and create web mapping applications or story maps. For information about the other capabilities please visit http://doc.arcgis.com/en/arcgis-online/.

The ArcGIS online platform is designed to host small datasets, for example demographic datasets. The datasets uploaded to ArcGIS online are relatively small in size, and should not exceed 1-2MB, or around 5000 records. This is to keep the agencies costs down and keep in line with our ArcGIS online pricing plan. It is for this reason that ArcGIS online should not be used to host large datasets, and tiled image services must NOT be uploaded to ArcGIS online. To publish bigger datasets and image services, please refer to the ArcGIS Server.

Source: http://discomap.eea.europa.eu/map/giseionet/Publishing_data_to_the_web_with_ArcGIS_Online.pdf

Wednesday, May 17, 2017

Code snippet: Identify to which polygon a point belong to?

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Code sample to find point inside a polygon in shape file using GDAL/OGR 2.x and C#.


using OSGeo.OGR;
using OSGeo.OSR;
using OSGeo.GDAL;
1:  public void FindPolygonBelongsToPoint()   
2:      {  
3:        try   
4:        {  
5:          var shapePath = @"C:\Locations_WGS84.shp";  
6:          Ogr.RegisterAll();  
7:          OSGeo.OGR.Driver shapeDriver = Ogr.GetDriverByName("ESRI Shapefile");  
8:          DataSource shape = shapeDriver.Open(shapePath, 0);  
9:          Layer layer = shape.GetLayerByIndex(0);  
10:    
11:          Feature polygonFeature = layer.GetNextFeature();  
12:    
13:          long featureCountInLayer = layer.GetFeatureCount(1);  
14:          for (int i = 1; i <= featureCountInLayer; i++) {  
15:    
16:            Geometry polygonGeom = polygonFeature.GetGeometryRef();  
17:    
18:            string coordinates = "POINT (-100.726 38.995)";  
19:    
20:            SpatialReference spatialRef = layer.GetSpatialRef();  
21:            Geometry point = Ogr.CreateGeometryFromWkt(ref coordinates, spatialRef);  
22:    
23:            bool isInside = point.Within(polygonGeom);  
24:    
25:            if (isInside)  
26:            {  
27:              var val = polygonFeature.GetFieldAsString(4);  
28:              Console.WriteLine("Found one");  
29:            }  
30:    
31:            polygonFeature = layer.GetNextFeature();            
32:          }         
33:            
34:        }  
35:        catch (Exception ex)   
36:        {  
37:    
38:          Console.WriteLine(ex.Message);  
39:        }          
40:        
41:      }  

Tuesday, May 2, 2017

Code snippet: To highlight selected feature in ArcMap programmatically using ArcObjects

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Code snippet to highlight selected feature in ArcMap programmatically using ArcObjects and return the STGeomFromWKB   string of selected feature.

To return the geometry you should import Microsoft.SqlServer.Types  from Nuget and SqlServerSpatial140.dll  from C:\Windows\System32

 using System;  
 using System.Collections.Generic;  
 using System.Data.SqlTypes;  
 using System.Linq;  
 using System.Runtime.InteropServices;  
 using System.Text;  
 using System.Windows;  
 using ESRI.ArcGIS.ArcMapUI;  
 using ESRI.ArcGIS.Carto;  
 using ESRI.ArcGIS.Catalog;  
 using ESRI.ArcGIS.CatalogUI;  
 using ESRI.ArcGIS.Desktop.AddIns;  
 using ESRI.ArcGIS.Display;  
 using ESRI.ArcGIS.esriSystem;  
 using ESRI.ArcGIS.Framework;  
 using ESRI.ArcGIS.Geodatabase;  
 using ESRI.ArcGIS.Geometry;  
 using Microsoft.SqlServer.Types;  
   
   
 namespace Test.Addin.ArcCommands  
 {  
   class SelectFeatureTool : ESRI.ArcGIS.Desktop.AddIns.Tool  
   {  
     protected override void OnMouseDown(MouseEventArgs arg)  
     {  
       IMxDocument mxDocument = ArcMap.Application.Document as IMxDocument;  
       IActiveView activeView = mxDocument.ActiveView;  
       IMap map = mxDocument.FocusMap;  
       ILayer layer = map.get_Layer(0); //Get 1st Layer  
       IFeatureLayer featureLayer = (IFeatureLayer) layer;  
   
       IPoint identifyPoint = activeView.ScreenDisplay.DisplayTransformation.ToMapPoint(arg.X, arg.Y);  
       ESRI.ArcGIS.Carto.IIdentify identifyLayer = (IIdentify)layer;  
       IArray array = identifyLayer.Identify(identifyPoint);  
         
       int oid = -1;  
       if (array != null)  
       {  
         object obj = array.get_Element(0);  
         IFeatureIdentifyObj fobj = obj as IFeatureIdentifyObj;  
         IRowIdentifyObject irow = fobj as IRowIdentifyObject;  
         IFeature feature = irow.Row as IFeature;  
         oid = feature.OID;  
       }  
       HighlightClickedFeature(featureLayer, oid, activeView);  
     }  
   

Python code snippet : Merge multiple CSVs (Column Wise) into a large CSV file using ID

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Following is the python code snippet to merge multiple CSVs into a large CSV (column wise) using CSV's unique ID field. All input CSV's must have same length.

 import csv
 import itertools
 
 outCombinedStatTxtName ="FormattedTxtResults.csv"  
 tempCsvFiles = glob.glob(str(TempFolderPath)+'\*.csv')  
 openedFileList = [open(fn, 'rb') for fn in tempCsvFiles]  
 readers = [csv.reader(fn) for fn in openedFileList]  
   
 result = open(outCombinedStatTxtName, 'wb')  
 writer = csv.writer(result,delimiter=',')  
   
 multipleIndices = False  
 for row_chunks in itertools.izip(*readers):  
   tempFormattedRow = list(itertools.chain.from_iterable(row_chunks))  
   fidIndices = [i for i, x in enumerate(tempFormattedRow) if x == "ID"]  
   if(len(fidIndices) > 1):  
     fidIndices.pop(0)  
     redundantIndices = tuple(fidIndices)  
     multipleIndices = True  
       
   if(multipleIndices):  
     tempFormattedRow = [ tempFormattedRow[i] for i in xrange(len(tempFormattedRow)) if i not in set(redundantIndices) ]      
     writer.writerow(tempFormattedRow)  
   else:  
     writer.writerow(tempFormattedRow)  
 result.close()     
 [fn.close() for fn in openedFileList]  


 

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