我有一個熊貓資料框：列標題稱為“位置”示例內容：“倫敦阿恩代爾中心”“曼徹斯特阿恩代爾”“伯明翰中央車站”“紐卡斯爾地鐵中心”
2個numpy陣列：
originalLocation = np.array(["London Arndale Centre","Manchester Arndale","Birmingham Central Station","Newcastle Metro Centre")
newLocation = np.array(["London","Manchester","Birmingham","Newcastle"]
我想在熊貓中創建一個新列：newLocation
結果需要是newLocation中的匹配列，其中位置欄位與原始位置numpy匹配。
例如：“London Arndale Centre”需要是“London” “Manchester Arndale”需要是“Manchester”
我試過這個，但它會拋出錯誤
df['newLocation'] = newLocation[int(np.where(originalLocation == df['Location'])[0])]
錯誤：ValueError：（'長度必須匹配才能比較'，（159，），（12，））
我在這里做錯了什么？
uj5u.com熱心網友回復：
好像您忘記了originalLocation陣列中的逗號。另外，int()也沒有必要。更新代碼：
df_data = ["London Arndale Centre", "Manchester Arndale", "Birmingham Central Station", "Newcastle Metro Centre"]
df = pd.DataFrame(df_data, columns=['Location'])
originalLocation = np.array(["London Arndale Centre", "Manchester Arndale", "Birmingham Central Station", "Newcastle Metro Centre"])
newLocation = np.array(["London","Manchester","Birmingham","Newcastle"])
df['newLocation'] = newLocation[np.where(originalLocation == df['Location'])[0]]
df
輸出：
Location newLocation
0 London Arndale Centre London
1 Manchester Arndale Manchester
2 Birmingham Central Station Birmingham
3 Newcastle Metro Centre Newcastle
編輯：正如您所提到merge的，即使并非所有值都包含在新位置中，也可以使用。我使用以下方法創建了一個小示例merge：
df_data = ["London Arndale Centre", "Manchester Arndale", "Birmingham Central Station", "Newcastle Metro Centre"]
df = pd.DataFrame(df_data, columns=['Location'])
originalLocation = ["London Arndale Centre", "Birmingham Central Station", "Newcastle Metro Centre"]
newLocation = ["London", "Birmingham", "Newcastle"]
df_new = pd.DataFrame({'Location': originalLocation,
'newLocation': newLocation})
df.merge(df_new, on='Location', how='left')
缺少曼徹斯特條目的輸出：
Location newLocation
0 London Arndale Centre London
1 Manchester Arndale NaN
2 Birmingham Central Station Birmingham
3 Newcastle Metro Centre
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