如何在 Pandas 中創建索引列名和循環？

Question

我正在嘗試為我的數據框（df）制作列名，例如

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

並將“頻率”設為索引 但是，我的代碼不起作用。 代碼中已經設置了變量 min、max 和 columnNum 我應該如何修復它？

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

您需要為分子創建一個空數據集，並且可以單獨創建索引：

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