4
我從其他人的python模塊引發異常(AttributeError: 'NoneType' object has no attribute 'append'
)的代碼片段。該片段是:聲明的列表引發NoneType異常
def generateFragments(self):
tr = self.deviceTransform()
if tr is None:
return
pts = np.empty((2,len(self.data['x'])))
pts[0] = self.data['x']
pts[1] = self.data['y']
pts = fn.transformCoordinates(tr, pts)
self.fragments = []
pts = np.clip(pts, -2**30, 2**30) ## prevent Qt segmentation fault.
## Still won't be able to render correctly, though.
for i in xrange(len(self.data)):
rec = self.data[i]
pos = QtCore.QPointF(pts[0,i], pts[1,i])
x,y,w,h = rec['fragCoords']
rect = QtCore.QRectF(y, x, h, w)
self.fragments.append(QtGui.QPainter.PixmapFragment.create(pos, rect))
和異常消息是:
[14:35:59] Ignored exception:
|==============================>>
| Traceback (most recent call last):
| File "/usr/lib/pymodules/python2.7/pyqtgraph/debug.py", line 35, in w
| func(*args, **kwds)
| File "/usr/lib/pymodules/python2.7/pyqtgraph/graphicsItems/ScatterPlotItem.py", line 714, in paint
| self.generateFragments()
| File "/usr/lib/pymodules/python2.7/pyqtgraph/graphicsItems/ScatterPlotItem.py", line 685, in generateFragments
| self.fragments.append(QtGui.QPainter.PixmapFragment.create(pos, rect))
| AttributeError: 'NoneType' object has no attribute 'append'
|
|==============================<<
這不是一個「修復我的錯誤」的問題,而是「這怎麼可能」的問題。上面的幾行,self.fragments
被聲明爲空列表。從那時起,self.fragments
的唯一修改是致電append()
。這種類型怎麼可能改變?追加操作中是否有可能會將列表類型更改爲NoneType
?
'self.data'屬性?如果是這樣,那麼可以在該函數中設置'self.fragments'爲'None'。我沒有看到任何可能導致問題的事情。 – 2014-10-28 05:05:17
是的,'self.data'是一個'numpy'數組 – 2014-10-28 05:14:34
第一次迭代是否發生異常? – 2014-10-28 05:18:44