Ogr::简化LineString输出到shp文件

Ogr::简化LineString输出到shp文件

OGR1.6 above
python2.4 above

只需要定义fields,roads数据调用serial_shpdata_road()即可一次输出到shp文件
不适合大批量坐标一次生成shp
ogr的问题在于python代码中初始化layer之后传递到其他函数使用将会导致莫名错误，应该是个bug

 1    http://www.2cto.com/kf/201203/121642.html
 2     fields=[
 3         {'name':'roadname','type':FIELD_STRING,'width':30}
 4     ]
 5     roads=[
 6         {
 7             'geom':[(121.1,31.1),(121.101,31.102),(121.101,31.2)],
 8             'attrs':('xscott.test',)
 9         }
10     ]
11     serial_shpdata_road('d:/temp3/aa.shp',fields,roads)
12 '''
13 def serial_shpdata_road(file,fields,roads):
14     '''
15         fields: [{name,type,width},]
16         roads - [{'geom':[(x,y),..],'wkt':'','attrs':[name,type,len,]},..]
17     '''
18     layer = None
19    
20     if os.path.exists(file):
21         os.remove(file)
22        
23     makePrjFile(file)
24     ds = driver.CreateDataSource(file)
25     layer = ds.CreateLayer("road",geom_type=ogr.wkbMultiLineString)
26     for f in fields:
27         fld = ogr.FieldDefn(f['name'],f['type'])
28        
29         if f['type'] == FIELD_STRING :
30             w = 30
31             if f.has_key('width'):
32                 w = f['width']
33             fld.SetWidth(w)
34         layer.CreateField(fld)
35     ftrdfn = layer.GetLayerDefn()
36    
37     for r in roads:
38         g = None
39         if r.has_key('wkt'):
40             g = ogr.CreateGeometryFromWkt(r['wkt'])
41         if r.has_key('geom'):
42             pts = r['geom']
43             pts = map(lambda pt: '%s %s'%(pt[0],pt[1]),pts)
44             txt = string.join(pts,',')
45             wkt = "MULTILINESTRING((%s))"%txt
46             g = ogr.CreateGeometryFromWkt(wkt)
47        
48         ftr = ogr.Feature(ftrdfn)
49         ftr.SetGeometry(g)
50         for n in range(len(r['attrs'])):
51             at = r['attrs'][n]
52             ftr.SetField(n,at)
53         layer.CreateFeature(ftr)
54     layer.SyncToDisk()
55