如何在 Pandas 中创建索引列名和循环？

Question

我正在尝试为我的数据框（df）制作列名，例如

>> 'Frequency','molecule1','molecule2',.....'molecule18' 

并将“频率”设为索引 但是，我的代码不起作用。 代码中已经设置了变量 min、max 和 columnNum 我应该如何修复它？

df=pd.DataFrame({'Frequency': np.arange(min,max+1)}, 
   columns=['Frequency','molecule{}'.format(x+1) for x in range(int(columnNum/2))]])
df.set_index('Frequency', inplace=True)

Answer 1

您需要为分子创建一个空数据集，并且可以单独创建索引：

import pandas as pd
import numpy as np

my_min = 10
my_max = 15
ncols = 5

frequency = pd.Series(np.arange(my_min, my_max+1), name="frequency")
nrows = len(frequency)

data = np.full(shape=(nrows, ncols), fill_value=np.nan)
df = (pd.DataFrame(data, index=frequency)
      .rename(columns=lambda col: col+1)   # columns are currently 0, 1, 2... increase them all by 1 to become 1, 2, 3...
      .add_prefix("Molecule")              # add "Molecule" to the beginning of each column name

print(df)
           Molecule1  Molecule2  Molecule3  Molecule4  Molecule5
frequency                                                       
10               NaN        NaN        NaN        NaN        NaN
11               NaN        NaN        NaN        NaN        NaN
12               NaN        NaN        NaN        NaN        NaN
13               NaN        NaN        NaN        NaN        NaN
14               NaN        NaN        NaN        NaN        NaN
15               NaN        NaN        NaN        NaN        NaN