pandas Python 向数组中添加项
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Python Add an Item to an Array
提问by Ledger Yu
I have an ndarray that looks like this:
我有一个看起来像这样的 ndarray：
In [1]: a
Out [1]: array(['x','y'], dtype=object)
Now I wanted to append a "z" to the end of it:
现在我想在它的末尾附加一个“z”：
In [2]: print([a,'z'])
[array(['x','y'],dtype=object), 'z']
Instead, what I want is:
相反，我想要的是：
['x','y','z']
Any idea?
任何的想法？
回答by Wenlong Liu
You can do it using numpy.append:
您可以使用numpy.append做到这一点：
import numpy as np
a = np.array(['x','y'])
b = np.append(a,['z'])
In [8]:b
Out[8]: array(['x', 'y', 'z'], dtype='<U1')
回答by Psidom
You can use numpy.append:
您可以使用numpy.append：
import numpy as np
a = np.array(['x', 'y'])
np.append(a, 'z')
# array(['x', 'y', 'z'],
# dtype='<U1')
回答by armatita
As alternative to append(since you can use it for several iterables; check for example: PEP3132) you can use the "unpacking" symbol to do it:
作为附加的替代方法（因为您可以将它用于多个可迭代对象；检查例如：PEP3132）您可以使用“解包”符号来执行此操作：
import numpy as np
a = np.array(['x','y'], dtype=object)
b = np.array([*a, "z"])
print(*a, "z")
print(b)
The result is this:
结果是这样的：
x y z
['x' 'y' 'z']
