解释下这段代码: if arcpy.Exists(segments): cursor = arcpy.da.SearchCursor(segments, ["osm_id", "SHAPE@"]) endpoints = {} segmentlengths = {} for row in cursor: row = list(row) row[0] = row[0].encode("gbk") # 记录该路段的起始坐标(所以是有两个坐标的) endpoints[row[0]] = ((row[1].firstPoint.X, row[1].firstPoint.Y), (row[1].lastPoint.X, row[1].lastPoint.Y)) [row[0]] = row[1].length del row del cursor print("Number of segments: " + str(len(endpoints))) # prepare segment layer for fast search arcpy.Delete_management('segments_lyr') arcpy.MakeFeatureLayer_management(segments, 'segments_lyr') return (endpoints,) else: print("segment file does not exist!")
时间: 2024-04-10 18:29:24 浏览: 80
这段代码是一个条件语句,首先判断一个名为segments"的文件是否存在。如果存在,代码会执行以下操作:
1. 创建一个名为"cursor"的搜索游标,用于在"segments"文件中检索指定的字段数据。
2. 创建两个空字典变量"endpoints"和"segmentlengths",用于存储该路段的起始坐标和路段长度。
3. 对于每一行数据,将其转换为列表形式,并对第一个元素进行gbk编码处理。
4. 将第一个元素(osm_id)作为键,将起始坐标(通过row[1].firstPoint和row[1].lastPoint获取)作为值存储在"endpoints"字典中。
5. 将第二个元素(路段长度)赋值给row[0],并存储在"segmentlengths"字典中。
6. 删除"row"变量和"cursor"游标对象。
7. 打印输出路段数量。
8. 删除名为"segments_lyr"的要素图层(如果存在)。
9. 使用"segments"文件创建一个名为"segments_lyr"的要素图层。
10. 返回包含"endpoints"字典的元组。
如果"segments"文件不存在,代码会输出一条错误信息:"segment file does not exist!"。
相关问题
试试优化这段代码: if arcpy.Exists(segments): cursor = arcpy.da.SearchCursor(segments, ["osm_id", "SHAPE@"]) endpoints = {} # 创建字典变量 for row in cursor: row = list(row) row[0] = row[0].encode("gbk") endpoints[row[0]] = ((row[1].firstPoint.X, row[1].firstPoint.Y), (row[1].lastPoint.X, row[1].lastPoint.Y)) # osm_id作主键,存储该路段的起点和终点坐标到endpoints字典 del row del cursor print("Number of segments: " + str(len(endpoints))) # prepare segment layer for fast search arcpy.Delete_management('segments_lyr') arcpy.MakeFeatureLayer_management(segments, 'segments_lyr') return (endpoints,) else: print("segment file does not exist!")
这段代码已经相对较优化,但还有一些改进的地方:
1. 不需要手动删除"row"和"cursor"变量,可以省略这两行代码。
2. 使用f-string来构建输出语句,更直观和简洁。
3. 可以将删除"segments_lyr"图层的操作放在文件存在的情况下执行,避免重复删除不存在的图层。
下面是优化后的代码:
```python
if arcpy.Exists(segments):
cursor = arcpy.da.SearchCursor(segments, ["osm_id", "SHAPE@"])
endpoints = {}
for row in cursor:
row = list(row)
row[0] = row[0].encode("gbk")
endpoints[row[0]] = ((row[1].firstPoint.X, row[1].firstPoint.Y), (row[1].lastPoint.X, row[1].lastPoint.Y))
print(f"Number of segments: {len(endpoints)}")
arcpy.Delete_management('segments_lyr')
arcpy.MakeFeatureLayer_management(segments, 'segments_lyr')
return (endpoints,)
else:
print("segment file does not exist!")
```
这样可以使代码更加清晰和简洁。
import arcpy # 定义工具参数 input_features = arcpy.GetParameterAsText(0) target_features = arcpy.GetParameterAsText(1) output_features = arcpy.GetParameterAsText(2) overlap_area = arcpy.GetParameterAsText(3) # 定义空间参考 spatial_reference = arcpy.Describe(input_features).spatialReference # 创建空图层来存储连接后的要素 arcpy.CreateFeatureclass_management("in_memory", "connected_features", "POLYLINE", spatial_reference) # 开始连接 with arcpy.da.SearchCursor(input_features, ["OID@", "SHAPE@"]) as input_cursor: with arcpy.da.SearchCursor(target_features, ["OID@", "SHAPE@"]) as target_cursor: with arcpy.da.InsertCursor("in_memory/connected_features", ["SHAPE@"]) as output_cursor: for input_row in input_cursor: for target_row in target_cursor: # 检查两个要素之间是否有重叠面 if input_row[1].overlaps(target_row[1]): intersection = input_row[1].intersect(target_row[1], 4) area = intersection.area # 如果重叠面积大于或等于指定值,则连接两个要素 if area >= float(overlap_area): polyline = arcpy.Polyline(input_row[1], target_row[1]) output_cursor.insertRow([polyline]) target_row = None input_row = None # 导出连接后的要素 arcpy.CopyFeatures_management("in_memory/connected_features", output_features) # 清理内存 arcpy.Delete_management("in_memory")运行错误IndentationError: unexpected indent (空间连接.py, line 15) 执行(kj)失败。请改正代码
这是一个缩进错误,可能是由于复制代码时导致的。请尝试将第15行的缩进调整到与前面的代码行相同的位置。以下是已经修复缩进错误的代码:
```python
import arcpy
# 定义工具参数
input_features = arcpy.GetParameterAsText(0)
target_features = arcpy.GetParameterAsText(1)
output_features = arcpy.GetParameterAsText(2)
overlap_area = arcpy.GetParameterAsText(3)
# 定义空间参考
spatial_reference = arcpy.Describe(input_features).spatialReference
# 创建空图层来存储连接后的要素
arcpy.CreateFeatureclass_management("in_memory", "connected_features", "POLYLINE", spatial_reference)
# 开始连接
with arcpy.da.SearchCursor(input_features, ["OID@", "SHAPE@"]) as input_cursor:
with arcpy.da.SearchCursor(target_features, ["OID@", "SHAPE@"]) as target_cursor:
with arcpy.da.InsertCursor("in_memory/connected_features", ["SHAPE@"]) as output_cursor:
for input_row in input_cursor:
for target_row in target_cursor:
# 检查两个要素之间是否有重叠面
if input_row[1].overlaps(target_row[1]):
intersection = input_row[1].intersect(target_row[1], 4)
area = intersection.area
# 如果重叠面积大于或等于指定值,则连接两个要素
if area >= float(overlap_area):
polyline = arcpy.Polyline(input_row[1], target_row[1])
output_cursor.insertRow([polyline])
target_row = None
input_row = None
# 导出连接后的要素
arcpy.CopyFeatures_management("in_memory/connected_features", output_features)
# 清理内存
arcpy.Delete_management("in_memory")
```