我有一個如下所示的數據框： Name Variable FieldA 2.3 412A 2.9 861A 3.5 1703B 3.5 1731A 4.0 2609B 4.0 2539A 4.6 2821B 4.6 2779A 5.2 3048B 5.2 2979A 5.8 3368B 5.8 3216如您所見，“變量”列有重復的值。我想計算 A 和 B 之間每個變量的增量 (%)。然后我想生成的數據幀是： Name Variable Field Ref field (A) Delta (A - B) A 2.3 412 412 0.0% A 2.9 861 861 0.0% A 3.5 1703 1703 0.0% B 3.5 1731 1703 -1.6% A 4.0 2609 2609 0.0% B 4.0 2539 2609 2.8% A 4.6 2821 2821 0.0% B 4.6 2779 2821 1.5% A 5.2 3048 3048 0.0% B 5.2 2979 3048 2.3% A 5.8 3368 3368 0.0% B 5.8 3216 3368 4.7%我已經用熊貓嘗試了一些東西，比如：df["Ref field (A)"] = df.apply(lambda row:df[(df["Variable"] == row["Variable"]) & (df["Name"] == "A")]["Field"][0],axis=1)但這不起作用...： File "pandas/_libs/index.pyx", line 106, in pandas._libs.index.IndexEngine.get_value File "pandas/_libs/index.pyx", line 114, in pandas._libs.index.IndexEngine.get_value File "pandas/_libs/index.pyx", line 162, in pandas._libs.index.IndexEngine.get_loc File "pandas/_libs/hashtable_class_helper.pxi", line 958, in pandas._libs.hashtable.Int64HashTable.get_item File "pandas/_libs/hashtable_class_helper.pxi", line 964, in pandas._libs.hashtable.Int64HashTable.get_item KeyError: (0, u'occurred at index 0') 有什么簡單可行的想法嗎？謝謝
1 回答
富國滬深
TA貢獻1790條經驗 獲得超9個贊
每組只有一個'A'值'Variable'，創建一個Series并映射這些值以獲取引用。
s = df[df.Name.eq('A')].set_index('Variable').Field
df['RefA'] = df.Variable.map(s)
df['Delta'] = (df.RefA - df.Field)/df.Field*100
輸出：（在唯一的B組和C組的末尾添加一行）
Name Variable Field RefA Delta
0 A 2.3 412 412.0 0.000000
1 A 2.9 861 861.0 0.000000
2 A 3.5 1703 1703.0 0.000000
3 B 3.5 1731 1703.0 -1.617562
4 C 3.5 1761 1703.0 -3.293583
5 A 4.0 2609 2609.0 0.000000
6 B 4.0 2539 2609.0 2.756991
7 A 4.6 2821 2821.0 0.000000
8 B 4.6 2779 2821.0 1.511335
9 A 5.2 3048 3048.0 0.000000
10 B 5.2 2979 3048.0 2.316213
11 A 5.8 3368 3368.0 0.000000
12 B 5.8 3216 3368.0 4.726368
13 B 6.5 1231 NaN NaN
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