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[英]iterate over pandas rows and set column values based on values in other column
[英]pandas iterate over rows based on column values
我想同時計算城市之間的溫差。 數據結構如下所示:
dic = {'city':['a','a','a','a','a','b','b','b','b','b'],'week':[1,2,3,4,5,3,4,5,6,7],'temp':[20,21,23,21,25,20,21,24,21,22]}
df = pd.DataFrame(dic)
df
+------+------+------+
| city | week | temp |
+------+------+------+
| a | 1 | 20 |
| a | 2 | 21 |
| a | 3 | 23 |
| a | 4 | 21 |
| a | 5 | 25 |
| b | 3 | 20 |
| b | 4 | 21 |
| b | 5 | 24 |
| b | 6 | 21 |
| b | 7 | 22 |
+------+------+------+
我想計算第 3、4 和 5 周 a 和 b 城市之間的溫度差異。最終的數據結構應如下所示:
+--------+-------+------+------+
| city_1 | city2 | week | diff |
+--------+-------+------+------+
| a | b | 3 | 3 |
| a | b | 4 | 0 |
| a | b | 5 | 1 |
+--------+-------+------+------+
我會旋轉你的數據,去掉 NA 值,然后直接做減法。 通過這種方式,您可以保持與每個城市相關的源溫度。
result = (
df.pivot(index='week', columns='city', values='temp')
.dropna(how='any', axis='index')
.assign(diff=lambda df: df['a'] - df['b'])
)
print(result)
city a b diff
week
3 23.0 20.0 3.0
4 21.0 21.0 0.0
5 25.0 24.0 1.0
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