Question

我可以使用一些关于如何处理Python脚本中的错误的建议。通过阅读本站点上的所有Python错误处理帖子，我能够收集的是，除了continue语句之外，您不能简单地绕过for循环中的错误。相反，您必须直接处理每个错误。这是我遇到问题的原因。我附加了在for循环中间发生的错误消息。另外，我附上了我的脚本，该脚本通过以下工作流程进行：

在栅格周围放置一个多边形
在多边形的平均中心放置一个点
使用该点来标识与其关联的特定县相应的栅格
根据选定的县多边形

如何将错误消息中的信息合并到try除continue语句之外，以便脚本可以移动到列表中的下一个栅格而不是在处理过程中停止？

# Import arcpy module
import arcpy
from arcpy import env
from arcpy.sa import *
arcpy.CheckOutExtension("3D")

# Set Over write
arcpy.env.overwriteOutput = 1

# Set the workspace
env.workspace = r"Z:\temp.gdb"
outworkspace = r"Z:\location2\temp2.gdb"

# Local variables:
counties = r"Z:\temp.gdb\boundaries\Counties"
counties_lyr = arcpy.MakeFeatureLayer_management(counties,"counties_lyr")

# Get the list of rasters to process
raster_list = arcpy.ListRasters("*_clp")
print raster_list

for raster in raster_list:
    # Define name and location for output raster
    name = outworkspace + "\\" + str(raster)

    # Process: Raster Domain
    arcpy.RasterDomain_3d(raster, "in_memory/temp", "POLYGON")

    # Process: Central Feature
    arcpy.MeanCenter_stats("in_memory/temp", "in_memory/temp1")

    # Process: Select Layer By Location
    arcpy.SelectLayerByLocation_management(counties_lyr, "intersect", "in_memory/temp1", "", "NEW_SELECTION")

    # Clip Raster
    arcpy.Clip_management(raster, "#", name,counties_lyr, "#", "ClippingGeometry")

    # Delete in_memory
    arcpy.Delete_management("in_memory")

    print "processing " + raster + " complete..."

print "All processing is now finished"

enter image description here

Answer 1

你可以处理for循环中的错误。将代码包装在try except块中将允许您在参数无效的情况下处理错误。

try:

# Process: Raster Domain
    arcpy.RasterDomain_3d(raster, "in_memory/temp", "POLYGON")

except ExcecuteError: 
  continue

这将发生在你的循环中，它基本上说如果发生异常会发出continue，这意味着继续下一个循环迭代。

你可以将try except块放在任何地方，正如Mark Amery建议你可以在try中包装整个for循环体。

Answer 2

这是你需要的吗？如果for循环中任何单个栅格出现任何问题，它将打印出回溯，然后转到下一个。

import traceback

# Import arcpy module
import arcpy
from arcpy import env
from arcpy.sa import *
arcpy.CheckOutExtension("3D")

# Set Over write
arcpy.env.overwriteOutput = 1

# Set the workspace
env.workspace = r"Z:\temp.gdb"
outworkspace = r"Z:\location2\temp2.gdb"

# Local variables:
counties = r"Z:\temp.gdb\boundaries\Counties"
counties_lyr = arcpy.MakeFeatureLayer_management(counties,"counties_lyr")

# Get the list of rasters to process
raster_list = arcpy.ListRasters("*_clp")
print raster_list

for raster in raster_list:
    try:
        # Define name and location for output raster
        name = outworkspace + "\\" + str(raster)

        # Process: Raster Domain
        arcpy.RasterDomain_3d(raster, "in_memory/temp", "POLYGON")

        # Process: Central Feature
        arcpy.MeanCenter_stats("in_memory/temp", "in_memory/temp1")

        # Process: Select Layer By Location
        arcpy.SelectLayerByLocation_management(counties_lyr, "intersect", "in_memory/temp1", "", "NEW_SELECTION")

        # Clip Raster
        arcpy.Clip_management(raster, "#", name,counties_lyr, "#", "ClippingGeometry")

        # Delete in_memory
        arcpy.Delete_management("in_memory")

        print "processing " + raster + " complete..."

    except:
        print "Something went wrong handling " + str(raster) + ". Here's a traceback:"
        traceback.print_exc()
        continue

print "All processing is now finished"

这是一个懒惰的程序员的实现，将for循环的全部内容包装在try ... except ...块中，它将捕获块中任何类型的异常。根据你的需要和品味，你可能会发现它更有帮助（或者只是更优雅）来捕捉你在实践中遇到的特定错误，正如dm03514建议的那样 - 但是我认为对于像这样的小脚本，其输出是要被人类看待，你做什么并不重要。

正如您在问题中指定的那样，对您来说重要的是您在发生错误时会看到回溯。这就是traceback.print_exc（）的用武之地。：）

Answer 3

我不知道arcpy。但也许可以通过以下方式处理第969行中的异常：

try:
    your stuff

except arcpy.ExecuteError, error:
    print error

可以提供帮助。

Answer 4

关于try / except / continue in for循环的内容并不十分清楚。以下内容基于您提供的代码。

def failing_func(raster):
    raise ValueError("raster <%s> function has failed" % (raster))

def working_func(raster):
    print("raster <%s> function has succeeded" % (raster))
    return True

raster_list = [0, 1, 2, 3, 4, 5]

for raster in raster_list:
    print("Processing <%s>" % (raster))

    try:
        v1 = working_func("raster_1")
        v2 = failing_func("raster_2")
        v3 = working_func("raster_3")
        v4 = failing_func("raster_4")
        v5 = working_func("raster_5")
    except ValueError, e:
        print("Exception was raised: %s when processing item %s" % (str(e), raster))
        continue

哪个输出：

Processing <0>
raster <raster_1> function has succeeded
Exception was raised: raster <raster_2> function has failed when processing item 0
Processing <1>
raster <raster_1> function has succeeded
Exception was raised: raster <raster_2> function has failed when processing item 1
Processing <2>
raster <raster_1> function has succeeded
Exception was raised: raster <raster_2> function has failed when processing item 2
Processing <3>
raster <raster_1> function has succeeded
Exception was raised: raster <raster_2> function has failed when processing item 3
Processing <4>
raster <raster_1> function has succeeded
Exception was raised: raster <raster_2> function has failed when processing item 4
Processing <5>
raster <raster_1> function has succeeded
Exception was raised: raster <raster_2> function has failed when processing item 5

错误处理Python arcpy脚本所需的建议

4 个答案: