嘗試迭代列並刪除pandas dataframe中具有特定字符串值的行

Question

我試圖找到一種方法來迭代DataFrame的每一列並檢查具有特定字符串的行，並將其刪除為機器學習練習的預處理步驟。 我手動執行此操作的代碼如下：

train = train[train.Native_Country != ' ?']
train = train[train.Race != ' ?']
train = train[train.Work_Class != ' ?']
train = train[train.Occupation != ' ?']
train = train[train.Relationship != ' ?']
train = train[train.Sex != ' ?']
train = train[train.Work_Class != ' ?']
train = train[train.Occupation != ' ?']
train = train[train.Education != ' ?']

必須有一種更簡單的方法來省略或刪除每列的這些特定行，我覺得我正在過度思考如何為loop-if循環執行此操作。

Answer 1

繼EdChum的回答之后，嘗試這樣的事情：

 columnsyouwant = ['Native_Country', 'Race', 'Work_Class'....]

 for col in columnsyouwant:
    train[col] = train[col].replace(' ?', None)

 train.dropna(inplace=True) #default is how='any' in axis=0 (rows)