在数据框中添加n个空行

问题描述

我想在具有深度列的深度范围内扩展此数据框:

I would like to expand this dataframe on a depth range which has such a depth column:

import numpy as np
import pandas as pd

depth = np.array([0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5])    

df1 = pd.DataFrame({'depth': [0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2],
           '400.0': [13.909261, 7.758734, 3.513627, 2.095409, 1.628918, 0.782643, 0.278548, 0.160153, -0.155895, -0.152373, -0.147820, -0.023997, 0.010729, 0.006050, 0.002356],
           '401.0': [14.581624, 8.173803, 3.757856, 2.223524, 1.695623, 0.818065, 0.300235, 0.173674, -0.145402, -0.144456, -0.142969, -0.022471, 0.010802, 0.006181, 0.002641],
           '402.0': [15.253988, 8.588872, 4.002085, 2.351638, 1.762327, 0.853486, 0.321922, 0.187195, -0.134910, -0.136539, -0.138118, -0.020945, 0.010875, 0.006313, 0.002927],
           '403.0': [15.633908, 8.833914, 4.146499, 2.431543, 1.798185, 0.874350, 0.333470, 0.192128, -0.130119, -0.134795, -0.136049, -0.019307, 0.012037, 0.006674, 0.003002],
           '404.0': [15.991816, 9.066159, 4.283401, 2.507818, 1.831721, 0.894119, 0.344256, 0.196415, -0.125758, -0.133516  , -0.134189, -0.017659, -0.013281,0.007053, 0.003061],
           '405.0': [16.349725, 9.298403, 4.420303, 2.584094, 1.865257, 0.913887, 0.355041, 0.200702, -0.121396, -0.132237, -0.132330, -0.016012, 0.014525, 0.007433, 0.003120]
           })

因此，在这种情况下，我需要在底部处添加具有NaN值的另外三行.

So what I need in this case is three additional rows at the bottom with NaN values.

类似地，我有一个df2，其深度范围为1.1到2.5，并且需要根据扩展的depth范围填充上部 3行.

Similarly I have a df2 with depth range from 1.1 to 2.5 and need to fill the upper 3 rows based on the extended depth range.

我该怎么做?

推荐答案

您可以使用merge

pd.DataFrame({'depth':depth}).merge(df1,how='left')

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