Python机器学习的报错

Question

操作环境是Anaconda
我的代码是

from sklearn.datasets import fetch_openml 
from matplotlib import pyplot as plt

mnist = fetch_openml('mnist_784')

x,y = mnist [ "data"] , mnist ["target"]
print("MINST数据集大小为：{}".format(x.shape))



for i in range (25):


    digit =x[i * 2500]



    digit_image = digit.reshape (28,28)

    plt.subplot(5,5, i +1)


    plt.axis ( ' off')



    plt.imshow (digit_image , cmap='gray ')


plt.show ()

报错

```python
MINST数据集大小为：(70000, 784)
Traceback (most recent call last):

  File "D:\Anaconda\lib\site-packages\pandas\core\indexes\base.py", line 3080, in get_loc
    return self._engine.get_loc(casted_key)

  File "pandas\_libs\index.pyx", line 70, in pandas._libs.index.IndexEngine.get_loc

  File "pandas\_libs\index.pyx", line 101, in pandas._libs.index.IndexEngine.get_loc

  File "pandas\_libs\hashtable_class_helper.pxi", line 4554, in pandas._libs.hashtable.PyObjectHashTable.get_item

  File "pandas\_libs\hashtable_class_helper.pxi", line 4562, in pandas._libs.hashtable.PyObjectHashTable.get_item

KeyError: 0


The above exception was the direct cause of the following exception:

Traceback (most recent call last):

  File "C:\Users\Administrator\untitled3.py", line 21, in <module>
    digit =x[i * 2500]

  File "D:\Anaconda\lib\site-packages\pandas\core\frame.py", line 3024, in __getitem__
    indexer = self.columns.get_loc(key)

  File "D:\Anaconda\lib\site-packages\pandas\core\indexes\base.py", line 3082, in get_loc
    raise KeyError(key) from err

KeyError: 0

该怎么解决呀~

Answer 1

from sklearn.datasets import fetch_openml 
from matplotlib import pyplot as plt

mnist = fetch_openml('mnist_784')

x,y = mnist["data"] , mnist["target"]
print("MINST数据集大小为：{}".format(x.shape))
for i in range(25):
    digit =x.loc[i*2500].to_numpy()
    digit_image = digit.reshape(28,28)
    plt.subplot(5,5, i +1)
    plt.axis('off')
    plt.imshow(digit_image, cmap='gray')
plt.show()

问题有两个，一.读入形式是DateFrame，读行可以用loc函数，二.reshape是用于ndarray的， 需要用to_numpy()函数转换