Python ogr.OFTString() Examples

def saveToShape(self, array, srs, outShapeFile):
        # Parse a delimited text file of volcano data and create a shapefile
        # use a dictionary reader so we can access by field name
        # set up the shapefile driver
        outDriver = ogr.GetDriverByName('ESRI Shapefile')

        # create the data source
        if os.path.exists(outShapeFile):
            outDriver.DeleteDataSource(outShapeFile)
        # Remove output shapefile if it already exists

        # options = ['SPATIALITE=YES'])
        ds = outDriver.CreateDataSource(outShapeFile)

        # create the spatial reference, WGS84

        lyrout = ds.CreateLayer('randomSubset', srs)
        fields = [
            array[1].GetFieldDefnRef(i).GetName() for i in range(
                array[1].GetFieldCount())]

        for f in fields:
            field_name = ogr.FieldDefn(f, ogr.OFTString)
            field_name.SetWidth(24)
            lyrout.CreateField(field_name)

        for k in array:
            lyrout.CreateFeature(k)

        # Save and close the data source
        ds = None 

def Add_Field(input_lyr, field_name, ogr_field_type):
    """
    Add a field to a layer using the following ogr field types:
    0 = ogr.OFTInteger
    1 = ogr.OFTIntegerList
    2 = ogr.OFTReal
    3 = ogr.OFTRealList
    4 = ogr.OFTString
    5 = ogr.OFTStringList
    6 = ogr.OFTWideString
    7 = ogr.OFTWideStringList
    8 = ogr.OFTBinary
    9 = ogr.OFTDate
    10 = ogr.OFTTime
    11 = ogr.OFTDateTime
    """

    # List fields
    fields_ls = List_Fields(input_lyr)

    # Check if field exist
    if field_name in fields_ls:
        raise Exception('Field: "{0}" already exists'.format(field_name))

    # Create field
    inp_field = ogr.FieldDefn(field_name, ogr_field_type)
    input_lyr.CreateField(inp_field)

    return inp_field 

def Add_Field(input_lyr, field_name, ogr_field_type):
    """
    Add a field to a layer using the following ogr field types:
    0 = ogr.OFTInteger
    1 = ogr.OFTIntegerList
    2 = ogr.OFTReal
    3 = ogr.OFTRealList
    4 = ogr.OFTString
    5 = ogr.OFTStringList
    6 = ogr.OFTWideString
    7 = ogr.OFTWideStringList
    8 = ogr.OFTBinary
    9 = ogr.OFTDate
    10 = ogr.OFTTime
    11 = ogr.OFTDateTime
    """

    # List fields
    fields_ls = List_Fields(input_lyr)

    # Check if field exist
    if field_name in fields_ls:
        raise Exception('Field: "{0}" already exists'.format(field_name))

    # Create field
    inp_field = ogr.FieldDefn(field_name, ogr_field_type)
    input_lyr.CreateField(inp_field)

    return inp_field 

def save_point_list_to_shapefile(class_sample_point_dict, out_path, geotransform, projection_wkt, produce_csv=False):
    """Saves a list of points to a shapefile at out_path. Need the gt and projection of the raster.
    GT is needed to move each point to the centre of the pixel. Can also produce a .csv file for CoolEarth"""
    log = logging.getLogger(__name__)
    log.info("Saving point list to shapefile")
    log.debug("GT: {}\nProjection: {}".format(geotransform, projection_wkt))
    driver = ogr.GetDriverByName("ESRI Shapefile")
    data_source = driver.CreateDataSource(out_path)
    srs = osr.SpatialReference()
    srs.ImportFromWkt(projection_wkt)
    layer = data_source.CreateLayer("validation_points", srs, ogr.wkbPoint)
    class_field = ogr.FieldDefn("class", ogr.OFTString)
    class_field.SetWidth(24)
    layer.CreateField(class_field)

    for map_class, point_list in class_sample_point_dict.items():
        for point in point_list:
            feature = ogr.Feature(layer.GetLayerDefn())
            coord = pyeo.coordinate_manipulation.pixel_to_point_coordinates(point, geotransform)
            offset = geotransform[1]/2   # Adds half a pixel offset so points end up in the center of pixels
            wkt = "POINT({} {})".format(coord[0]+offset, coord[1]-offset) # Never forget about negative y values in gts.
            new_point = ogr.CreateGeometryFromWkt(wkt)
            feature.SetGeometry(new_point)
            feature.SetField("class", map_class)
            layer.CreateFeature(feature)
            feature = None

    layer = None
    data_source = None

    if produce_csv:
        csv_out_path = out_path.rsplit('.')[0] + ".csv"
        with open(csv_out_path, "w") as csv_file:
            writer = csv.writer(csv_file)
            writer.writerow(["id", "yCoordinate", "xCoordinate"])

            # Join all points create single dimesional list of points (and revise the '*' operator)
            for id,  point in enumerate(itertools.chain(*class_sample_point_dict.values())):
                coord = pyeo.coordinate_manipulation.pixel_to_point_coordinates(point, geotransform)
                offset = geotransform[1] / 2  # Adds half a pixel offset so points end up in the center of pixels
                lat = coord[0] + offset
                lon = coord[1] - offset
                writer.writerow([id, lon, lat])
        log.info("CSV out at: {}".format(csv_out_path)) 

def lineWriting(fn,ln_lyrName_w,ref_lyr=False):
    ds=ogr.Open(fn,1)
    
    '''参考层，用于空间坐标投影，字段属性等参照'''
    ref_lyr=ds.GetLayer(ref_lyr)
    ref_sr=ref_lyr.GetSpatialRef()
    print(ref_sr)
    ref_schema=ref_lyr.schema #查看属性表字段名和类型
    for field in ref_schema:
        print(field.name,field.GetTypeName())      

    '''建立新layer层'''    
    if ds.GetLayer(ln_lyrName_w):
        ds.DeleteLayer(ln_lyrName_w)    
    ln_lyr=ds.CreateLayer(ln_lyrName_w,ref_sr,ogr.wkbMultiLineString)    

    '''配置字段，名称以及类型和相关参数'''
    Fd=ogr.FieldDefn("length",ogr.OFTReal)
    Fd.SetWidth(8)
    Fd.SetPrecision(3)
    ln_lyr.CreateField(Fd)
    Fd=ogr.FieldDefn("name",ogr.OFTString)
    ln_lyr.CreateField(Fd)    

    '''建立feature空特征和设置geometry几何类型'''
    print(ln_lyr.GetLayerDefn())
    ln_feat=ogr.Feature(ln_lyr.GetLayerDefn())

    for feat in ref_lyr:  #循环feature
        '''设置几何体'''
        ln_ref=feat.geometry().Clone()
        temp=""
        for j in range(ln_ref.GetPointCount()):
            if j==ln_ref.GetPointCount()-1:
                temp+="%f %f"%(float(ln_ref.GetX(j)+0.01) , float(ln_ref.GetY(j)+0.01))
            else:
                temp+="%f %f,"%(float(ln_ref.GetX(j)+0.01) , float(ln_ref.GetY(j)+0.01))
        wkt="LINESTRING(%s)" % temp  #使用wkt的方法建立直线
#        print(wkt)
        newLn=ogr.CreateGeometryFromWkt(wkt)        
        ln_feat.SetGeometry(newLn)
        '''设置字段值'''
        ln_feat.SetField("name",feat.GetField("name"))
        ln_feat.SetField("length",newLn.Length())
        '''根据设置的几何体和字段值，建立feature。循环建立多个feature特征'''
        ln_lyr.CreateFeature(ln_feat)    
    del ds 

def polygonWriting(fn,pg_lyrName_w,ref_lyr=False):
    ds=ogr.Open(fn,1)
    
    '''参考层，用于空间坐标投影，字段属性等参照'''
    ref_lyr=ds.GetLayer(ref_lyr)
    ref_sr=ref_lyr.GetSpatialRef()
#    print(ref_sr)
    ref_schema=ref_lyr.schema #查看属性表字段名和类型
    for field in ref_schema:
        print(field.name,field.GetTypeName())      

    '''建立新layer层'''    
    if ds.GetLayer(pg_lyrName_w):
        ds.DeleteLayer(pg_lyrName_w)    
    pg_lyr=ds.CreateLayer(pg_lyrName_w,ref_sr,ogr.wkbMultiPolygon)    

    '''配置字段，名称以及类型和相关参数'''
    Fd=ogr.FieldDefn("area",ogr.OFTReal)
    Fd.SetWidth(8)
    Fd.SetPrecision(8)
    pg_lyr.CreateField(Fd)
    Fd=ogr.FieldDefn("name",ogr.OFTString)
    pg_lyr.CreateField(Fd)    

    '''建立feature空特征和设置geometry几何类型'''
#    print(pg_lyr.GetLayerDefn())
    pg_feat=ogr.Feature(pg_lyr.GetLayerDefn())
    
    for feat in ref_lyr:  #循环feature
        '''设置几何体'''
        pg_ref=feat.geometry().Clone()
        tempSub=""
        for j in range(pg_ref.GetGeometryCount()):
            ring=pg_ref.GetGeometryRef(j)
            vertexes=ring.GetPoints()
#            print(len(vertexes))
            temp=""
            for i in range(len(vertexes)):                
                if i==len(vertexes)-1:
                    temp+="%f %f"%(float(vertexes[i][0]+0.01) , float(vertexes[i][1]+0.01))
                else:
                    temp+="%f %f,"%(float(vertexes[i][0]+0.01) , float(vertexes[i][1]+0.01))
            if j==pg_ref.GetGeometryCount()-1:
                tempSub+="(%s)"%temp   
            else:
                tempSub+="(%s),"%temp
#        print(tempSub)    
        wkt="POLYGON(%s)" % tempSub  #使用wkt的方法建立直线
#        print(wkt)
        newPg=ogr.CreateGeometryFromWkt(wkt)        
        pg_feat.SetGeometry(newPg)
        
        '''设置字段值'''
        pg_feat.SetField("name",feat.GetField("NAME"))
        pg_feat.SetField("area",newPg.GetArea())
        '''根据设置的几何体和字段值，建立feature。循环建立多个feature特征'''
        pg_lyr.CreateFeature(pg_feat)    
    del ds