如何從Python中的分組數據中過濾

Question

如何在Python中從分組數據集中進行過濾

s=train['PdDistrict'].value_counts()
print(s)

對於上面的代碼，輸出如下所示：SOUTHERN 157182 MISSION 119908

現在我需要在執行value_counts時單獨過濾PdDistrict ='MISSION'。
我該如何實現？

Answer 1

創建一個樣本數據框

train = pd.DataFrame({
        "A": ["MISSION", "SOUTHERN", "MISSION", "MISSION", "MISSION", "SOUTHERN"],
        "B": [0, 0, 0, 1, 1, 1]
    })

首先為數據框分配具有MISSION值的列A s

s = train[train['A'] == 'MISSION']

然后計算A列中的值

s['A'].value_counts()

輸出：

MISSION    4
Name: A, dtype: int64