更新ArcPy特征类

Question

我正在寻找加速我的剧本的方法。最终的输出是需要的，但是它很笨重，而且速度很慢。我知道这很慢，因为双for..in..循环。那么，我怎样才能让它变得更流畅呢？

我的脚本更新了现有的特征类。我有两个文件夹，其中所有最新的形状文件(shp)存储。我的脚本检查每个文件夹中的shps，然后在4个地理数据库中搜索相同的命名特性类(这些是旧版本)。因此，shp必须转到已经包含相同名称的功能类的gdb。我希望它足够简单。为了让你知道，运行这个脚本需要一个多小时，我有大约45个shapefiles (~1gb)，这些文件被复制到4个地理数据库中。

有没有办法避免这些耗时的双for..in..循环？我需要指出的是，文件夹存储在与gdb不同的服务器上，这也是其速度慢的主要原因。当我只使用C驱动器测试脚本时，花费了6-8分钟！

import time
import arcpy


startTime = time.clock()

print "Start"

FCProducts = r"C:\Python\DataConversion\shapefiles"
GBProducts = r"C:\Python\DataConversion\shapefile_gp"
adminBdry = r"C:\Python\DataConversion\temp1.gdb"
GnR = r"C:\DataConversion\temp2.gdb"
Invenories = r"C:\Python\DataConversion\temp3.gdb"
NFE = r"C:\Python\DataConversion\temp4.gdb"


arcpy.env.overwriteOutput = True

arcpy.env.workspace = FCProducts
listFC = [0]
listFC = arcpy.ListFeatureClasses()
del arcpy.env.workspace

for product in listFC:
    f2fOutput = product[:-4] + "_new"

    arcpy.env.workspace = GnR
    listGnrFC = arcpy.ListFeatureClasses()
    for gnrFC in listGnrFC:
        if gnrFC == product[:-4]:
            arcpy.FeatureClassToFeatureClass_conversion(product[:-4], GnR, f2fOutput)
            print product, " copied to ", GnR
            arcpy.Delete_management(gnrFC)
            print "old ", gnrFC, " deleted"
            arcpy.Rename_management(f2fOutput, product[:-4])
            print "output renamed", "\n"

    arcpy.env.workspace = adminBdry
    listAdBdryFC = arcpy.ListFeatureClasses()
    for AdBdry in listAdBdryFC:
        if AdBdry == product[:-4]:
            arcpy.FeatureClassToFeatureClass_conversion(product[:-4], adminBdry, f2fOutput)
            print product, " copied to ", adminBdry
            arcpy.Delete_management(AdBdry)
            print "old ", AdBdry, " deleted"
            arcpy.Rename_management(f2fOutput, product[:-4])
            print "output renamed", "\n"

    arcpy.env.workspace = Invenories
    listInventFC = arcpy.ListFeatureClasses()
    for invent in listInventFC:
        if invent == product[:-4]:
            arcpy.FeatureClassToFeatureClass_conversion(product[:-4], Invenories, f2fOutput)
            print product, " copied to ", Invenories
            arcpy.Delete_management(invent)
            print "old ", invent, " deleted"
            arcpy.Rename_management(f2fOutput, product[:-4])
            print "output renamed", "\n"

    arcpy.env.workspace = NFE
    listNfeFC = arcpy.ListFeatureClasses()
    for nfe in listNfeFC:
        if nfe == product[:-4]:
            arcpy.FeatureClassToFeatureClass_conversion(product[:-4], NFE, f2fOutput)
            print product, " copied to ", NFE
            arcpy.Delete_management(nfe)
            print "old ", nfe, " deleted"
            arcpy.Rename_management(f2fOutput, product[:-4])
            print "output renamed", "\n"

arcpy.env.workspace = GBProducts
listFCgb = [0]
listFCgb = arcpy.ListFeatureClasses()

for productGB in listFCgb:
    f2fOutputGB = productGB[:-4] + "_new"
    arcpy.env.workspace = Invenories
    listInventGB = arcpy.ListFeatureClasses()
    for InventGB in listInventGB:
        if InventGB == productGB[:-4]:
            arcpy.FeatureClassToFeatureClass_conversion(productGB[:-4], Invenories, f2fOutputGB)
            print productGB, " copied to ", Invenories
            arcpy.Delete_management(InventGB)
            print "old ", InventGB, " deleted"
            arcpy.Rename_management(f2fOutputGB, productGB[:-4])
            print "output renamed", "\n"

    arcpy.env.workspace = NFE
    listNfeGB = arcpy.ListFeatureClasses()
    for nfeGB in listNfeGB:
        if nfeGB == productGB[:-4]:
            arcpy.FeatureClassToFeatureClass_conversion(productGB[:-4], NFE, f2fOutputGB)
            print productGB, " copied to ", NFE
            arcpy.Delete_management(nfeGB)
            print "old ", nfeGB, " deleted"
            arcpy.Rename_management(f2fOutputGB, productGB[:-4])
            print "output renamed", "\n"
print "completed within:", time.clock() - startTime, "seconds", "\n"

我正在使用Windows，ArcGis 10.0，Python2.6.6

Answer 1

，不要重复，

首先，最不重要的是，Python花费更多的时间构建子字符串，而不是局部变量查找。因此，您可以通过在循环开始时命名product[:-4]来稍微改进一些。

更重要的是，大多数代码都是相似的：

• 设置一个新的工作空间；
• 用它建立一个类的列表；
• 对于这些类中的每一个：
  • 转换类；
  • 删除旧的；
  • 重新命名新的。

唯一需要更改的是:工作区的名称和所涉及的产品的名称。只需编写一个函数来处理它一次：

import arcpy


FCProducts = r"C:\Python\DataConversion\shapefiles"
GBProducts = r"C:\Python\DataConversion\shapefile_gp"
adminBdry = r"C:\Python\DataConversion\temp1.gdb"
GnR = r"C:\DataConversion\temp2.gdb"
Invenories = r"C:\Python\DataConversion\temp3.gdb"
NFE = r"C:\Python\DataConversion\temp4.gdb"

arcpy.env.overwriteOutput = True

def convert_class(workspace, product_name, output_name):
    arcpy.env.workspace = workspace
    for product in arcpy.ListFeatureClasses():
        if product == product_name:
            arcpy.FeatureClassToFeatureClass_conversion(product_name, workspace, output_name)
            print product_name, " copied to ", workspace
            arcpy.Delete_management(product)
            print "old ", product, " deleted"
            arcpy.Rename_management(output_name, product_name)
            print "output renamed", "\n"

arcpy.env.workspace = FCProducts
listFC = arcpy.ListFeatureClasses()

for product in listFC:
    f2fOutput = product[:-4] + "_new"
    product_name = product[:-4]
    convert_class(GnR, product_name, f2fOutput)
    convert_class(adminBdry, product_name, f2fOutput)
    convert_class(Invenories, product_name, f2fOutput)
    convert_class(NFE, product_name, f2fOutput)

arcpy.env.workspace = GBProducts
listFCgb = arcpy.ListFeatureClasses()

for productGB in listFCgb:
    f2fOutputGB = productGB[:-4] + "_new"
    product_name = productGB[:-4]
    convert_class(Invenories, product_name, f2fOutput)
    convert_class(NFE, product_name, f2fOutput)

节省资源使用

既然代码更容易阅读，那么它到底在做什么呢？对于每个项目，您要切换工作空间2或4次。切换工作区含义：

• 打开文件；
• 读它；
• 解析它；
• 用它构建数据结构。

即使对每个项目执行一次，也是对时间和计算资源的巨大浪费。最好打开一个工作区一次，迭代每个产品，然后切换到另一个工作区。单个工作区的代码布局如下所示：

def process_workspace(workspace, products):
    arcpy.env.workspace = workspace
    for product in products:
        product_name = product[:-4]
        output_name = product_name + "_new"
        for item in arcpy.ListFeatureClasses():
            if item == product_name:
                arcpy.FeatureClassToFeatureClass_conversion(product_name, workspace, output_name)
                print product, " copied to ", workspace
                arcpy.Delete_management(item)
                print "old ", item, " deleted"
                arcpy.Rename_management(output_name, product_name)
                print "output renamed\n"

然后，只需在每次*.gdb处理之前更改一次工作区：

arcpy.env.workspace = FCProducts
listFC = arcpy.ListFeatureClasses()
process_workspace(GnR, listFC)
process_workspace(adminBdry, listFC)
process_workspace(Invenories, listFC)
process_workspace(NFE, listFC)

arcpy.env.workspace = GBProducts
listGB = arcpy.ListFeatureClasses()
process_workspace(Invenories, listGB)
process_workspace(NFE, listGB)

您甚至可以在工作区上使用for循环来改进布局。

把所有的东西放在一起，

通过在PEP8上加入更多的在线长度和变量命名，我们可以得到以下结果：

import arcpy

FC_PRODUCTS = r"C:\Python\DataConversion\shapefiles"
GB_PRODUCTS = r"C:\Python\DataConversion\shapefile_gp"

ADMIN_BOUNDARY = r"C:\Python\DataConversion\temp1.gdb"
GNR = r"C:\DataConversion\temp2.gdb"
INVENORIES = r"C:\Python\DataConversion\temp3.gdb"
NFE = r"C:\Python\DataConversion\temp4.gdb"


def process_workspace(workspace, products):
    arcpy.env.workspace = workspace
    for product in products:
        product_name = product[:-4]
        output_name = product_name + "_new"
        for item in arcpy.ListFeatureClasses():
            if item == product_name:
                arcpy.FeatureClassToFeatureClass_conversion(
                    product_name, workspace, output_name)
                print product, " copied to ", workspace
                arcpy.Delete_management(item)
                print "old ", item, " deleted"
                arcpy.Rename_management(output_name, product_name)
                print "output renamed\n"

arcpy.env.workspace = FC_PRODUCTS
products = arcpy.ListFeatureClasses()
for workspace in (GNR, ADMIN_BOUNDARY, INVENORIES, NFE):
    process_workspace(workspace, products)

arcpy.env.workspace = GB_PRODUCTS
products = arcpy.ListFeatureClasses()
for workspace in (INVENORIES, NFE):
    process_workspace(workspace, products)