Python學習筆記：實驗設計組合(一)

import pandas as pd
import numpy as np
df1 = pd.read_excel('實驗設計試解.xlsx', sheet_name = '實驗設計')
df2 = pd.read_excel('實驗設計試解.xlsx', sheet_name = '水準表')

df = pd.DataFrame(np.full((6, 7), np.nan))
df.columns = list(df1.columns)

print('實驗設計組合：')
df1

實驗設計組合：

print('水準表：')
df2

水準表：

print('預期結果：')
df

預期結果：

print('這種寫法會有語法上的問題：')
for i in df.columns:
    for j in df.index:
        df[i][j] = df2[i][df1[i][j]]
df

這種寫法會有語法上的問題：

c:userssuperuserminiconda3libsite-packagesipykernel_launcher.py:4: SettingWithCopyWarning: 
A value is trying to be set on a copy of a slice from a DataFrame

See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#returning-a-view-versus-a-copy
  after removing the cwd from sys.path.
c:userssuperuserminiconda3libsite-packagespandascoreindexing.py:205: SettingWithCopyWarning: 
A value is trying to be set on a copy of a slice from a DataFrame

See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#returning-a-view-versus-a-copy
  self._setitem_with_indexer(indexer, value)

print('另一種更有效率的寫法：')
df = pd.DataFrame(np.full((6, 7), np.nan))
df.columns = list(df1.columns)

for x in df.columns:
  for y in df2.index:
    df[x] = np.where(df1[x] == y, df2[x][y], df[x])
df

另一種更有效率的寫法：

print('改良自第一種，修正語法：')
df = df1

for x in df.columns:
  for y in df2.index:
    df.loc[df[x] == y, x] = df2[x][y]
df

改良自第一種，修正語法：