我需要为我的QGIS项目加载几个向量层,以便在每个向量层中测试脚本的每个功能。然而,最终我只想处理一到两个感兴趣的层,而放弃其他层,所以我想自动地这样做
我用一些层成功地做到了这一点,但有一层给我带来了问题,我还没有弄清楚原因
下面是一些代码:
加载层(这些层肯定不是问题几乎):
a2 = iface.addVectorLayer(path + ardida2, "", "ogr")
if not a2:
print("Layer failed to load!")
a3 = iface.addVectorLayer(path + ardida3, "", "ogr")
if not a3:
print("Layer failed to load!")
现在,我创建了这个函数来删除所有加载的层,除了我想使用的层。这个prints
之所以出现,仅仅是因为我试图理解这个问题
def RemoveAllLayersExcept(*layers):
layer_ids = []
for l in layers:
layer_ids.append(l.id())
print('layer_ids', layer_ids)
for lyr in QgsProject.instance().mapLayers():
print(lyr)
if lyr not in layer_ids:
print('not')
QgsProject.instance().removeMapLayer(lyr)
else:
pass
然后,我创建了一个新的层-一个给我带来问题的层。我需要在以后的迭代过程中编辑此层。我遵循了OpenSourceOptions教程中一个名为PyQGIS: Create a Shapefile的分步示例:
# OPENSOURCEOPTIONS TUTORIAL - PYQGIS: Create a Shapefile
# create fields
layerFields = QgsFields()
layerFields.append(QgsField('ID', QVariant.Int))
layerFields.append(QgsField('Value', QVariant.Double))
layerFields.append(QgsField('Name', QVariant.String))
# Now define the file path for the new shapefile
# Note: the CRS used here is NAD 1983 UTM Zone 11 N
fn = 'D:/Sara/Trabalho/QGIS/pnogas/fireball_points.shp'
writer = QgsVectorFileWriter(fn, 'UTF-8', layerFields, QgsWkbTypes.Point,QgsCoordinateReferenceSystem('EPSG:26912'), 'ESRI Shapefile')
# For each feature we need to set the geometry (in this case a point)
# set the attribute values, then add it to the vector layer.
feat = QgsFeature() # create an empty QgsFeature()
feat.setGeometry(QgsGeometry.fromPointXY(QgsPointXY(cx14, cy14))) # create a point and use it to set the feature geometry
feat.setAttributes([1, 1.1, 'one']) # set the attribute values
writer.addFeature(feat) # add the feature to the layer
layer_fireball = iface.addVectorLayer(fn, '', 'ogr')
if not layer_fireball:
print("Layer failed to load!")
del(writer)
然后我移除了我不感兴趣的图层:
RemoveAllLayersExcept(layer, layer_fireball)
就是这样。当我第一次运行程序时,什么都没有发生。以下是我得到的:
layer_ids ['COS2018_ardida2018_3_clip_cbf56f4b_e668_4c2e_9259_7d22d5943097', 'fireball_points_f92b32e0_f8bf_42c1_95e6_b317ddf6ee84']
COS2018_ardida2018_2_clip_45b241c4_fb9b_4654_9916_5ff08514c559
not
COS2018_ardida2018_3_clip_cbf56f4b_e668_4c2e_9259_7d22d5943097
fireball_points_f92b32e0_f8bf_42c1_95e6_b317ddf6ee84
这正是我所期望的。但在第二次和第n次中,我得到:
Layer failed to load!
Traceback (most recent call last):
File "C:\PROGRA~1\QGIS3~1.10\apps\Python37\lib\code.py", line 90, in runcode
exec(code, self.locals)
File "<input>", line 1, in <module>
File "<string>", line 676, in <module>
File "<string>", line 104, in RemoveAllLayersExcept
AttributeError: 'NoneType' object has no attribute 'id'
你能发现问题出在哪里吗?为什么会出现这种错误?为什么它只发生在第二次跑步之后
谢谢
更改
RemoveAllLayersExcept
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