arcpy如何用游标把一个字段求和

在ArcGIS Pro中，arcpy模块主要用于编写Python脚本操作地理数据库。如果你想要使用游标（Cursor）对表单或表层数据集中的某个字段进行求和，你可以按照以下步骤进行：

首先，导入必要的库：

import arcpy
from arcpy.da import cursors

假设你想对名为"FieldName"的字段求和，数据源是表格工作空间中的表"YourTable":

# 定义数据源和字段名
data_source = "path_to_your_table.gdb/YourTable"
field_name = "FieldName"

# 创建游标对象
with arcpy.da.Cursor(data_source) as cursor:
    # 初始化总和变量
    total_sum = 0

    # 遍历游标，累加每个记录的字段值
    for row in cursor:
        total_sum += row[field_name]

# 输出求和结果
print(f"Field '{field_name}' sum is: {total_sum}")

记得替换`path_to_your_table.gdb/YourTable`为你的实际数据源路径。

相关问题

import sys sys.tracebacklimit = 0 import os os.environ['PYTHONUNBUFFERED'] = '1' import arcpy 获取参数 input_features = arcpy.GetParameterAsText(0) join_field = arcpy.GetParameterAsText(1) target_feature = arcpy.GetParameterAsText(2) target_field = arcpy.GetParameterAsText(3) area_threshold = arcpy.GetParameterAsText(4) 创建空间连接 join_result = arcpy.SpatialJoin_analysis(input_features, target_feature, "in_memory/spatial_join", "JOIN_ONE_TO_ONE", "KEEP_ALL", "", "INTERSECT") 使用MakeFeatureLayer创建要素图层，并使用AddFieldDelimiters处理字段名称 join_layer = arcpy.management.MakeFeatureLayer(join_result, "join_layer").getOutput(0) join_field_name = arcpy.AddFieldDelimiters(join_layer, join_field) 使用SelectLayerByAttribute选择重叠面积大于阈值的要素 arcpy.management.SelectLayerByAttribute(join_layer, "NEW_SELECTION", "Shape_Area > " + str(area_threshold)) 使用SummaryStatistics工具进行面积求和 summary_table = arcpy.Statistics_analysis(join_layer, "in_memory/summary_table", [["Shape_Area", "SUM"]], join_field_name) 使用TableToNumPyArray将结果转换为字典 sum_dict = {} with arcpy.da.TableToNumPyArray(summary_table, [join_field, "SUM_Shape_Area"]) as arr: for row in arr: sum_dict[row[0]] = row 使用UpdateCursor更新目标要素类的目标字段 with arcpy.da.UpdateCursor(target_feature, [target_field, join_field], sql_clause=(None, "ORDER BY OBJECTID")) as cursor: for row in cursor: join_value = row[1] if join_value in sum_dict: area_sum = sum_dict[join_value] row[0] = area_sum cursor.updateRow(row) 导出结果 output_feature = arcpy.GetParameterAsText(5) arcpy.CopyFeatures_management(target_feature, output_feature) 删除游标对象和要素图层对象 del cursor, join_layer请改正为可复制代码

import sys
import os
import arcpy

# 禁用traceback，避免出现异常时输出堆栈信息
sys.tracebacklimit = 0

# 设置PYTHONUNBUFFERED环境变量，避免使用arcpy输出信息时出现延迟
os.environ['PYTHONUNBUFFERED'] = '1'

# 获取参数
input_features = arcpy.GetParameterAsText(0)
join_field = arcpy.GetParameterAsText(1)
target_feature = arcpy.GetParameterAsText(2)
target_field = arcpy.GetParameterAsText(3)
area_threshold = arcpy.GetParameterAsText(4)

# 创建空间连接
join_result = arcpy.SpatialJoin_analysis(input_features, target_feature, "in_memory/spatial_join", "JOIN_ONE_TO_ONE", "KEEP_ALL", "", "INTERSECT")

# 使用MakeFeatureLayer创建要素图层，并使用AddFieldDelimiters处理字段名称
join_layer = arcpy.management.MakeFeatureLayer(join_result, "join_layer").getOutput(0)
join_field_name = arcpy.AddFieldDelimiters(join_layer, join_field)

# 使用SelectLayerByAttribute选择重叠面积大于阈值的要素
arcpy.management.SelectLayerByAttribute(join_layer, "NEW_SELECTION", "Shape_Area > " + str(area_threshold))

# 使用SummaryStatistics工具进行面积求和
summary_table = arcpy.Statistics_analysis(join_layer, "in_memory/summary_table", [["Shape_Area", "SUM"]], join_field_name)

# 使用TableToNumPyArray将结果转换为字典
sum_dict = {}
with arcpy.da.TableToNumPyArray(summary_table, [join_field, "SUM_Shape_Area"]) as arr:
for row in arr:
sum_dict[row[0]] = row

# 使用UpdateCursor更新目标要素类的目标字段
with arcpy.da.UpdateCursor(target_feature, [target_field, join_field], sql_clause=(None, "ORDER BY OBJECTID")) as cursor:
for row in cursor:
join_value = row[1]
if join_value in sum_dict:
area_sum = sum_dict[join_value]["SUM_Shape_Area"]
row[0] = area_sum
cursor.updateRow(row)

# 导出结果
output_feature = arcpy.GetParameterAsText(5)
arcpy.CopyFeatures_management(target_feature, output_feature)

# 删除游标对象和要素图层对象
del cursor, join_layer

import sys sys.tracebacklimit = 0 import os os.environ['PYTHONUNBUFFERED'] = '1' import arcpy # 获取参数 input_features = arcpy.GetParameterAsText(0) join_field = arcpy.GetParameterAsText(1) target_feature = arcpy.GetParameterAsText(2) target_field = arcpy.GetParameterAsText(3) area_threshold = arcpy.GetParameterAsText(4) # 创建空间连接 join_result = arcpy.SpatialJoin_analysis(input_features, target_feature, "in_memory/spatial_join", "JOIN_ONE_TO_ONE", "KEEP_ALL", "", "INTERSECT") # 使用MakeFeatureLayer创建要素图层，并使用AddFieldDelimiters处理字段名称 join_layer = arcpy.management.MakeFeatureLayer(join_result, "join_layer").getOutput(0) join_field_name = arcpy.AddFieldDelimiters(join_layer, join_field) # 使用SelectLayerByAttribute选择重叠面积大于阈值的要素 arcpy.management.SelectLayerByAttribute(join_layer, "NEW_SELECTION", "Shape_Area > " + str(area_threshold)) # 使用SummaryStatistics工具进行面积求和 summary_table = arcpy.Statistics_analysis(join_layer, "in_memory/summary_table", [["Shape_Area", "SUM"]], [join_field_name]) # 使用TableToNumPyArray将结果转换为字典 sum_dict = {} with arcpy.da.TableToNumPyArray(summary_table, [join_field, "SUM_Shape_Area"]) as arr: for row in arr: sum_dict[row[0]] = row[1] # 使用UpdateCursor更新目标要素类的目标字段 with arcpy.da.UpdateCursor(target_feature, [target_field, join_field], sql_clause=(None, "ORDER BY OBJECTID")) as cursor: for row in cursor: join_value = row[1] if join_value in sum_dict: area_sum = sum_dict[join_value] row[0] = area_sum cursor.updateRow(row) # 导出结果 output_feature = arcpy.GetParameterAsText(5) arcpy.CopyFeatures_management(target_feature, output_feature) # 删除游标对象和要素图层对象 del cursor, join_layer运行错误：Traceback (most recent call last): ExecuteError: 执行失败。参数无效。 WARNING 000725: 输出表: 数据集 in_memory\summary_table 已存在。 ERROR 000728: 表中不存在字段 "数据" 执行(Statistics)失败。 执行(ccc)失败。请改正代码

代码中有多个错误：
1. 在创建空间连接时，输出结果已经指定为"in_memory/spatial_join"，因此在SpatialJoin_analysis函数中不需要再指定输出结果。
2. 在使用SummaryStatistics工具时，需要将join_field_name和"SUM_Shape_Area"包含在一个列表中，即[[join_field_name, "SUM_Shape_Area"]]。
3. 在使用UpdateCursor更新目标要素类的目标字段时，目标字段是target_field而不是"数据"。
4. 在删除游标对象和要素图层对象时，应该使用del语句删除两个对象，即del cursor, del join_layer。

以下是修改后的代码示例：

import sys
sys.tracebacklimit = 0
import os
os.environ['PYTHONUNBUFFERED'] = '1'
import arcpy

# 获取参数
input_features = arcpy.GetParameterAsText(0)
join_field = arcpy.GetParameterAsText(1)
target_feature = arcpy.GetParameterAsText(2)
target_field = arcpy.GetParameterAsText(3)
area_threshold = arcpy.GetParameterAsText(4)

# 创建空间连接
join_result = arcpy.SpatialJoin_analysis(input_features, target_feature, "in_memory/spatial_join", "JOIN_ONE_TO_ONE", "KEEP_ALL", "", "INTERSECT")

# 使用MakeFeatureLayer创建要素图层，并使用AddFieldDelimiters处理字段名称
join_layer = arcpy.management.MakeFeatureLayer(join_result, "join_layer").getOutput(0)
join_field_name = arcpy.AddFieldDelimiters(join_layer, join_field)

# 使用SelectLayerByAttribute选择重叠面积大于阈值的要素
arcpy.management.SelectLayerByAttribute(join_layer, "NEW_SELECTION", "Shape_Area > " + str(area_threshold))

# 使用SummaryStatistics工具进行面积求和
summary_table = arcpy.Statistics_analysis(join_layer, "in_memory/summary_table", [[join_field_name, "SUM_Shape_Area"]], [join_field_name])

# 使用TableToNumPyArray将结果转换为字典
sum_dict = {}
with arcpy.da.TableToNumPyArray(summary_table, [join_field, "SUM_Shape_Area"]) as arr:
    for row in arr:
        sum_dict[row[0]] = row[1]

# 使用UpdateCursor更新目标要素类的目标字段
with arcpy.da.UpdateCursor(target_feature, [target_field, join_field], sql_clause=(None, "ORDER BY OBJECTID")) as cursor:
    for row in cursor:
        join_value = row[1]
        if join_value in sum_dict:
            area_sum = sum_dict[join_value]
            row[0] = area_sum
            cursor.updateRow(row)

# 导出结果
output_feature = arcpy.GetParameterAsText(5)
arcpy.CopyFeatures_management(target_feature, output_feature)

# 删除游标对象和要素图层对象
del cursor, join_layer