Python - dataframe apply - Using conditional to generate new column in pandas dataframe - 在dataframe新建column以現有的其他column的value為條件

Python版本：Python 3.6.0 :: Anaconda 4.3.1 (64-bit)
Pandas版本：0.19.2
系統版本：Windows 10

在資料分析中，時常會遇到要將類別資料與數值資料間轉換的情況

numerical variable to categorical variable or categorical variable to numerical variable

import pandas as pd
# create dataframe
number = [1,2,3,4,5]
sex = ['male','female','female','female','male']
df_new = pd.DataFrame()
df_new['number'] = number
df_new['sex'] = sex
df_new.head()

# create def for category to number 0/1
def tran_cat_to_num(df):
    if df['sex'] == 'male':
        return 1
    elif df['sex'] == 'female':
        return 0
# create sex_new 
df_new['sex_new']=df_new.apply(tran_cat_to_num,axis=1)
df_new

執行結果：

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