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关于python:基于shapefile的离群点提取

jiezi

extract.py
from pathlib import Path
from osgeo import ogr, osr, gdal
import os
import shutil
def buffer(inShp, fname, bdistance=0.02):

"""
:param inShp: 输出的矢量门路
:param fname: 输入的矢量门路
:param bdistance: 缓冲区间隔
:return:
"""
ogr.UseExceptions()
in_ds = ogr.Open(inShp)
f = open(inShp.replace('.shp','.prj'))
f_ = f.readline()
in_lyr = in_ds.GetLayer()
# 创立输入 Buffer 文件
driver = ogr.GetDriverByName('ESRI Shapefile')
if Path(fname).exists():
    driver.DeleteDataSource(fname)
# 新建 DataSource，Layer
out_ds = driver.CreateDataSource(fname)
out_lyr = out_ds.CreateLayer(fname, in_lyr.GetSpatialRef(), ogr.wkbPolygon)
def_feature = out_lyr.GetLayerDefn()
# # 新建 area 字段
# new_field = ogr.FieldDefn("Area", ogr.OFTReal)
# new_field.SetWidth(40)
# new_field.SetPrecision(20)  # 设置面积精度, 小数点后 16 位
# out_lyr.CreateField(new_field)
# 遍历原始的 Shapefile 文件给每个 Geometry 做 Buffer 操作
for feature in in_lyr:
    geometry = feature.GetGeometryRef()
    buffer = geometry.Buffer(bdistance)
    out_feature = ogr.Feature(def_feature)
    out_feature.SetGeometry(buffer)
    out_lyr.CreateFeature(out_feature)
    out_feature = None
out_ds.FlushCache()
del in_ds, out_ds

def area(shpPath):

'''计算面积'''
max_area = 0
driver = ogr.GetDriverByName("ESRI Shapefile")
dataSource = driver.Open(shpPath, 1)
layer = dataSource.GetLayer()
new_field = ogr.FieldDefn("Area", ogr.OFTReal)
new_field.SetWidth(32)
new_field.SetPrecision(16)  # 设置面积精度, 小数点后 16 位
layer.CreateField(new_field)
for feature in layer:
    geom = feature.GetGeometryRef()
    area = geom.GetArea()  # 计算面积
    if area > max_area:
        max_area = area
    feature.SetField("Area", area)  # 将面积增加到属性表中
    layer.SetFeature(feature)
dataSource = None
return max_area

def multipoly2poly(inputshp, outputshp):

"""
:param inputshp: 输出的矢量门路
:param outputshp: 输入的矢量门路
:return:
"""
gdal.UseExceptions()
driver = ogr.GetDriverByName('ESRI Shapefile')
in_ds = driver.Open(inputshp, 0)
in_lyr = in_ds.GetLayer()
if os.path.exists(outputshp):
    driver.DeleteDataSource(outputshp)
out_ds = driver.CreateDataSource(outputshp)
out_lyr = out_ds.CreateLayer('poly', geom_type=ogr.wkbPolygon)
for in_feat in in_lyr:
    geom = in_feat.GetGeometryRef()
    if geom.GetGeometryName() == 'MULTIPOLYGON':
        for geom_part in geom:
            addPolygon(geom_part.ExportToWkb(), out_lyr)
    else:
        addPolygon(geom.ExportToWkb(), out_lyr)

def addPolygon(simplePolygon, out_lyr):

featureDefn = out_lyr.GetLayerDefn()
polygon = ogr.CreateGeometryFromWkb(simplePolygon)
out_feat = ogr.Feature(featureDefn)
out_feat.SetGeometry(polygon)
out_lyr.CreateFeature(out_feat)
# print('Polygon added.')

def uni(shpPath, fname):

"""
:param shpPath: 输出的矢量门路
:param fname: 输入的矢量门路
:return:
"""driver = ogr.GetDriverByName("ESRI Shapefile")
dataSource = driver.Open(shpPath, 1)
layer = dataSource.GetLayer()
# 新建 DataSource，Layer
out_ds = driver.CreateDataSource(fname)
out_lyr = out_ds.[PM](https://www.gendan5.com/wallet/PerfectMoney.html)CreateLayer(fname, layer.GetSpatialRef(), ogr.wkbPolygon)
def_feature = out_lyr.GetLayerDefn()
# 遍历原始的 Shapefile 文件给每个 Geometry 做 Buffer 操作
# current_union = layer[0].Clone()
print('the length of layer:', len(layer))
if len(layer) == 0:
    return
for i, feature in enumerate(layer):
    geometry = feature.GetGeometryRef()
    if i == 0:
        current_union = geometry.Clone()
    current_union = current_union.Union(geometry).Clone()
    if i == len(layer) - 1:
        out_feature = ogr.Feature(def_feature)
        out_feature.SetGeometry(current_union)
        out_lyr.ResetReading()
        out_lyr.CreateFeature(out_feature)

def remove_big_buffer(shpPath, outputShp, area_thresold):

'''计算面积'''
driver = ogr.GetDriverByName("ESRI Shapefile")
dataSource = driver.Open(shpPath, 1)
layer = dataSource.GetLayer()
new_field = ogr.FieldDefn("Area", ogr.OFTReal)
new_field.SetWidth(32)
new_field.SetPrecision(16)  # 设置面积精度, 小数点后 16 位
layer.CreateField(new_field)
# 新建 DataSource，Layer
out_ds = driver.CreateDataSource(outputShp)
out_lyr = out_ds.CreateLayer(outputShp, layer.GetSpatialRef(), ogr.wkbPolygon)
def_feature = out_lyr.GetLayerDefn()
for feature in layer:
    geom = feature.GetGeometryRef()
    area = geom.GetArea()  # 计算面积
    if area > area_thresold * 1.2:
        continue
    feature.SetField("Area", area)  # 将面积增加到属性表中
    layer.SetFeature(feature)
    out_feature = ogr.Feature(def_feature)
    out_feature.SetGeometry(geom)
    out_lyr.CreateFeature(out_feature)
    out_feature = None
out_ds.FlushCache()
del dataSource, out_ds

def intersection(shp1, shp2, outshp):

"""
:param shp1:   缓冲区矢量门路
:param shp2:   指标矢量门路
:param outshp:  输入矢量门路
:return:
"""driver = ogr.GetDriverByName("ESRI Shapefile")
dataSource1 = driver.Open(shp1, 1)
layer1 = dataSource1.GetLayer()
dataSource2 = driver.Open(shp2, 1)
layer2 = dataSource2.GetLayer()
spatialref = layer2.GetSpatialRef()
# 新建 DataSource，Layer
out_ds = driver.CreateDataSource(outshp)
out_lyr = out_ds.CreateLayer(outshp, spatialref, ogr.wkbPolygon)
def_feature = out_lyr.GetLayerDefn()
for feature in layer1:
    geom = feature.GetGeometryRef()
    for feature_ in layer2:
        geom_ = feature_.GetGeometryRef()
        if geom.Intersect(geom_) == 1:
            out_feature = ogr.Feature(def_feature)
            out_feature.SetGeometry(geom_)
            out_lyr.CreateFeature(out_feature)
out_ds.FlushCache()
del dataSource1, dataSource2

def mkdir(path):

if not os.path.exists(path):
    os.mkdir(path)

def mainfunc(inShp, outshp, bdistance):

temproot = './temp'
mkdir(temproot)
fname = f'{temproot}/buffer.shp'
fname2 = f'{temproot}/buffer2.shp'
buffer(inShp, fname, bdistance=bdistance)
max_area = area(fname)
uni(fname, fname2)
multipoly2poly(fname2, fname)
remove_big_buffer(fname, fname2, max_area)
uni(fname2, fname)
intersection(fname, inShp, outshp)
# remove temporary directory
if os.path.exists(temproot):
    shutil.rmtree(temproot)

if name == ‘__main__’:

f = open('config_order.txt')
data = f.readlines()
inShp = data[0].replace('\n', '')
outshp = data[1].replace('\n', '')
bdistance = float(data[2].replace('\n', ''))
print(inShp, outshp)
mainfunc(inShp, outshp, bdistance)

config_order.txt
./data/buildings.shp
isolated_buildings.shp
0.008

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