Python 类型错误：无法解包不可迭代的 NoneType 对象
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TypeError: cannot unpack non-iterable NoneType object
提问by Neha Devi Shakya
I know this question has been asked before but I can't seem to get mine to work. Can someone help me out with this?
我知道以前有人问过这个问题，但我似乎无法让我的工作。有人可以帮我解决这个问题吗？
import numpy as np
def load_dataset():
def download(filename, source="http://yaan.lecun.com/exdb/mnist/"):
print ("Downloading ",filename)
import urllib
urllib.urlretrieve(source+filename,filename)
import gzip
def load_mnist_images(filename):
if not os.path.exists(filename):
download(filename)
with gzip.open(filename,"rb") as f:
data=np.frombuffer(f.read(), np.uint8, offset=16)
data = data.reshape(-1,1,28,28)
return data/np.float32(256)
def load_mnist_labels(filename):
if not os.path.exists(filename):
download(filename)
with gzip.open(filename,"rb") as f:
data = np.frombuffer(f.read(), np.uint8, offset=8)
return data
X_train = load_mnist_images("train-images-idx3-ubyte.gz")
y_train = load_mnist_labels("train-labels-idx1-ubyte.gz")
X_test = load_mnist_images("t10k-images-idx3-ubyte.gz")
y_test = load_mnist_labels("t10k-labels-idx1-ubyte.gz")
return X_train, y_train, X_test, y_test
X_train, y_train, X_test, y_test = load_dataset()
import matplotlib
matplotlib.use("TkAgg")
import matplotlib.pyplot as plt
plt.show(plt.imshow(X_train[3][0]))
This is the error I am getting:
这是我得到的错误：
Traceback (most recent call last):
File "C:\Users\nehad\Desktop\Neha\Non-School\Python\Handwritten Digits
Recognition.py", line 38, in <module>
X_train, y_train, X_test, y_test = load_dataset()
TypeError: cannot unpack non-iterable NoneType object
I am new to machine learning. Did I just miss something simple? I am trying a Handwritten Digit Recognition project for my school Science Exhibition.
我是机器学习的新手。我只是错过了一些简单的事情吗？我正在为我的学校科学展览尝试手写数字识别项目。
Thanks in advance!
提前致谢！
采纳答案by Amaras
I think your X_train, y_train, X_test, y_testare defined inside your load_mnist_imagesfunction, and are thus not defined for your load_datasetfunction.
我认为你X_train, y_train, X_test, y_test是在你的load_mnist_images函数中定义的，因此不是为你的load_dataset函数定义的。
You should de-indent your 5 lines from X_train = ...to return X_train, ...and your code might work better then.
您应该从X_train = ...to取消缩进 5 行，return X_train, ...然后您的代码可能会更好地工作。
回答by Nicolas Gervais
You get this error when you perform a multiple assignment to None(which is of NoneType). For instance:
当您对None( 的NoneType)执行多重分配时，您会收到此错误。例如：
X_train, y_train, X_test, y_test = None
TypeError: cannot unpack non-iterable NoneType object
类型错误：无法解包不可迭代的 NoneType 对象
So if you get this, the error is most likely that the right-hand part of the assignment is not what you expected.
所以如果你得到这个，错误很可能是作业的右手部分不是你所期望的。
回答by eyal sec
because load_dataset() return None.
因为 load_dataset() 返回 None。
run this and you get the same error: X_train, y_train, X_test, y_test = None
运行这个，你会得到同样的错误：X_train, y_train, X_test, y_test = None
