我有用于機器學習研究的數據，但我堅持使用這些字符串特征。我想將 ) 映射them(object到number(int64).例如，在 feature 中workclass，制作一個map(dict)as {'private':0,'State-gov':1, etc}。那么，如何在 DataFrame 中處理它，我是否應該編寫一個 for 循環來查找特征中的 n 個不同類，并為每個對象特征進行 n 鍵映射？# There are the code about data readingimport pandas as pddf_trainFeatures = pd.read_csv('data/trainFeatures.csv')object_features = ['workclass','education','Marital-status',         'occupation','occupation','relationship','race','sex','native-country']# list data typefor i in df_trainFeatures:    print(df_trainFeatures[i].dtype,i)//Printingint64 ageobject workclassint64 fnlwgtobject educationint64 education-numobject Marital-statusobject occupationobject relationshipobject raceobject sexint64 capital-gainint64 capital-lossint64 hours-per-weekobject native-country子數據框如下：