python - 我想分解一个 numpy 数组并将值多次应用于单列

Question

我想分解 numpy.ndarray 并将数组的每个值应用于数据帧的第一个元素。这是输入内容

Here is my dataframe

Id       Dept

100    Healthcare


Here is my numpy.ndarray

array(['2007-01-03', '2007-01-10', '2007-01-17', '2007-01-24'], dtype='datetime64[D]')


The Output looks like    
Id       Dept            Date

100    Healthcare        2007-01-03
100    Healthcare        2007-01-10
100    Healthcare        2007-01-17
100    Healthcare        2007-01-24

​

我需要帮助来实现这个逻辑。

Answer 1

您可以使用pandas.concat并使用数组的长度:

x = np.array(['2007-01-03', '2007-01-10', '2007-01-17', '2007-01-24'], dtype='datetime64[D]')

df = pd.concat([df]*len(x))
df['Date'] = x

print(df)
    Id        Dept       Date
0  100  Healthcare 2007-01-03
0  100  Healthcare 2007-01-10
0  100  Healthcare 2007-01-17
0  100  Healthcare 2007-01-24