reshape函数:改变数组的维数(注意不是shape大小)
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>>> e = np.arange( 10 )
>>> e
array([ 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ])
>>> e.reshape( 1 , 1 , 10 )
array([[[ 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]]])
>>> e.reshape( 1 , 1 , 10 )
array([[[ 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]]])
>>> e.reshape( 1 , 10 , 1 )
array([[[ 0 ],
[ 1 ],
[ 2 ],
[ 3 ],
[ 4 ],
[ 5 ],
[ 6 ],
[ 7 ],
[ 8 ],
[ 9 ]]])
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squeeze 函数:从数组的形状中删除单维度条目,即把shape中为1的维度去掉
用法:numpy.squeeze(a,axis = None)
1)a表示输入的数组;
2)axis用于指定需要删除的维度,但是指定的维度必须为单维度,否则将会报错;
3)axis的取值可为None 或 int 或 tuple of ints, 可选。若axis为空,则删除所有单维度的条目;
4)返回值:数组
5) 不会修改原数组;
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>>> a = e.reshape( 1 , 1 , 10 )
>>> a
array([[[ 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]]])
>>> np.squeeze(a)
array([ 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ])
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体现在画图时
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>>> plt.plot(a)
Traceback (most recent call last):
File "<stdin>" , line 1 , in <module>
File "C:\Python27\lib\site-packages\matplotlib\pyplot.py" , line 3240 , in plot
ret = ax.plot( * args, * * kwargs)
File "C:\Python27\lib\site-packages\matplotlib\__init__.py" , line 1710 , in inner
return func(ax, * args, * * kwargs)
File "C:\Python27\lib\site-packages\matplotlib\axes\_axes.py" , line 1437 , in plot
for line in self ._get_lines( * args, * * kwargs):
File "C:\Python27\lib\site-packages\matplotlib\axes\_base.py" , line 404 , in _grab_next_args
for seg in self ._plot_args(this, kwargs):
File "C:\Python27\lib\site-packages\matplotlib\axes\_base.py" , line 384 , in _plot_args
x, y = self ._xy_from_xy(x, y)
File "C:\Python27\lib\site-packages\matplotlib\axes\_base.py" , line 246 , in _xy_from_xy
"shapes {} and {}" . format (x.shape, y.shape))
ValueError: x and y can be no greater than 2 - D, but have shapes ( 1L ,) and ( 1L , 1L , 10L )
>>> plt.plot(np.squeeze(a))
[<matplotlib.lines.Line2D object at 0x00000000146CD940 >]
>>> plt.show()
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>>> np.squeeze(a).shape
( 10L ,)
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通过np.squeeze()函数转换后,要显示的数组变成了秩为1的数组,即(10,)
参考:http://blog.csdn.net/zenghaitao0128/article/details/78512715
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原文链接:https://blog.csdn.net/tracy_leaf/article/details/79297121