使用python在Google Earth引擎中使用大型FeatureCollection进行查询
使用python在Google Earth引擎中使用大型FeatureCollection进行查询
提问于 2017-07-13 19:58:49
我正在尝试处理从here下载的坦桑尼亚形状文件。
# im -> {Image} ee.Image({...})
# self.geom_coll -> {FeatureCollection} ee.FeatureCollection({...}). containing
# 3000 features.
# spacereducer() -> ee.Reducer.mean
# self.scale -> 10 #Changing this value to small number gives error
feats = im.reduceRegions(self.geom_coll, spacereducer(), self.scale)
flist = getInfo_werrorcontrol(feats,
self.errorcheck)['features']。
def getInfo_werrorcontrol(featureCollection, errorcontrolon=True):
"""
Wrapper to add error control to GEE evaluations.
For large computations GEE sometimes times out and needs to be
restarted. This does so in a controlled manner with out
interrrupting the program flow.
"""
if errorcontrolon:
i=0
while True:
try:
with timeout.timeout(10*60):
return featureCollection.getInfo() # In this line I am getting exception.
except NameError:
exc_type, exc_value, exc_traceback = sys.exc_info()
lines = traceback.format_exception(exc_type, exc_value, exc_traceback)
print ''.join('!! ' + line for line in lines)
i+=1
print 'attempts: '+str(i)
if i > 20:
raise ValueError('to many attempts')
elif i > 10:
print 'waiting 2 minutes'
time.sleep(60*2)
else:
return featureCollection.getInfo()将self.scale更改为10时，将引发以下line错误：
featureCollection.getInfo()
ee.ee_exception.EEException:服务器返回HTTP代码: 413
将self.scale更改为1000会抛出以下错误：
ee.ee_exception.EEException:计算超时
处理较大区域的shape文件的正确方法是什么？
回答 1
Stack Overflow用户
发布于 2017-07-19 07:28:09
请注意，对Earth Engine API的请求是already wrapped with exponential backoff。所以你的代码不会做太多的事情来解决这个问题。这些错误是如何从您发布的代码中产生的并不明显，但在任何一种情况下，答案都可能是相同的:导出结果。示例：
import ee
ee.Initialize()
image = ee.Image('srtm90_v4')
geometry = ee.Geometry.Polygon([[[-113.64, 39.97], [-113.64, 38.13],[-109.42, 38.13],[-109.42, 39.97]]], None, False)
dict = image.reduceRegion(reducer=ee.Reducer.mean(), geometry=geometry, scale=1000)
featureCollection = ee.FeatureCollection([ee.Feature(None, dict)])
task = ee.batch.Export.table.toDrive(collection=featureCollection, description='foo', fileNamePrefix='foo', fileFormat='CSV')
task.start()
print task.status()导出的输出将在您的Google Drive文件夹中实现。要了解更多有关scale的信息，请参阅this doc。
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原文链接：
https://stackoverflow.com/questions/45079976
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