我在 python 中有一個三維 xarray 構建為
import numpy as np
import pandas as pd
import xarray as xr
data_np = np.array([
[ [1, 2, 0, 8], [3, 4, 11, 2], [5, 6, 43, 90] ],
[ [7, 8, 2, 66], [9, 10, 31, 21], [11, 12, 56, 45] ]
])
dims = ['patient', 'parameter', 'day']
coords = {'patient':['Joe','Bill'], 'parameter':['a', 'b', 'c'], 'day':[0, 1, 2, 3]}
data = xr.DataArray(data_np, dims = dims, coords = coords )
我想將其匯出到具有以下結構的 Excel 表中：
期望輸出
使用 Pandas 資料框，我可以獲得所有變數（dims）沿同一軸分支的 Excel 表：
df = data.to_dataframe('value')
df = df.transpose()
with pd.ExcelWriter("main.xlsx") as writer:
df.to_excel(writer)
獲得的輸出：
我怎樣才能獲得所需的結構？
uj5u.com熱心網友回復：
您可以使用unstack()方法根據需要排列資料：
import numpy as np
import pandas as pd
import xarray as xr
data_np = np.array([
[ [1, 2, 0, 8], [3, 4, 11, 2], [5, 6, 43, 90] ],
[ [7, 8, 2, 66], [9, 10, 31, 21], [11, 12, 56, 45] ]
])
dims = ['patient', 'parameter', 'day']
coords = {'patient':['Joe','Bill'], 'parameter':['a', 'b', 'c'], 'day':[0, 1, 2, 3]}
data = xr.DataArray(data_np, dims = dims, coords = coords )
df = data.to_series().unstack(level=[1,2])
with pd.ExcelWriter("main.xlsx") as writer:
df.to_excel(writer)
或者您可以避免使用xarray和使用pd.MultiIndex直接從 NumPy 陣列創建 DataFrame：
import numpy as np
import pandas as pd
data_np = np.array([
[ [1, 2, 0, 8], [3, 4, 11, 2], [5, 6, 43, 90] ],
[ [7, 8, 2, 66], [9, 10, 31, 21], [11, 12, 56, 45] ]
])
dims = ['patient', 'parameter', 'day']
coords = {'patient':['Joe','Bill'], 'parameter':['a', 'b', 'c'], 'day':[0, 1, 2, 3]}
mi = pd.MultiIndex.from_product([coords[dims[i]] for i in range(3)], names=dims)
df = pd.Series(data_np.flatten(), index=mi).unstack(level=[1,2])
with pd.ExcelWriter("main.xlsx") as writer:
df.to_excel(writer)
uj5u.com熱心網友回復：
使用unstack：
data.to_dataframe('value').unstack(level=[1, 2]).droplevel(level=0, axis=1) \
.rename_axis(index=None, columns=['Parameter', 'Patient / Day'])
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