根据shapefile或多边形将栅格裁剪成numpy数组

Question

我有一个很大的栅格文件，我想根据多边形或shapefile裁剪到6个numpy数组。我有shapefile，也有作为geopandas数据框的多边形。谁能帮我使用python（no arcpy）做到这一点

Answer 1

我已经创建了一个小发电机，它可以满足您的需求。我选择了生成器，而不是直接遍历这些功能，因为如果您想检查数组，这将更加方便。如果需要，您仍然可以遍历生成器。

import gdal
import ogr, osr

# converts coordinates to index

def bbox2ix(bbox,gt):
    xo = int(round((bbox[0] - gt[0])/gt[1]))
    yo = int(round((gt[3] - bbox[3])/gt[1]))
    xd = int(round((bbox[1] - bbox[0])/gt[1]))
    yd = int(round((bbox[3] - bbox[2])/gt[1]))
    return(xo,yo,xd,yd)

def rasclip(ras,shp):
    ds = gdal.Open(ras)
    gt = ds.GetGeoTransform()

    driver = ogr.GetDriverByName("ESRI Shapefile")
    dataSource = driver.Open(shp, 0)
    layer = dataSource.GetLayer()

    for feature in layer:

        xo,yo,xd,yd = bbox2ix(feature.GetGeometryRef().GetEnvelope(),gt)
        arr = ds.ReadAsArray(xo,yo,xd,yd)
        yield arr

    layer.ResetReading()
    ds = None
    dataSource = None

假设您的shapefile被调用了，shapefile.shp并且您的栅格big_raster.tif可以这样使用：

gen = rasclip('big_raster.tif','shapefile.shp')

# manually with next

clip = next(gen)

## some processing or inspection here

# clip with next feature

clip = next(gen)

# or with iteration

for clip in gen:

    ## apply stuff to clip
    pass # remove