我有一個專欄。如何創建一個新列來計算重復的正負信號？
col1
-5
-3
-7
4
5
-0.5
6
8
9
col1 count_sign
-5 3
-3 3
-7 3
4 2
5 2
-0.5 1
6 3
8 3
9 3
前 3 行是 3，因為我們在前 3 行中有 3 個負號，然后是 2 個正號，然后......
uj5u.com熱心網友回復：
# identify the change of signs among rows,
# making count as NaN, where sign is same, else 1
df['count']=np.where(np.sign(df['col1']).diff().eq(0),
np.nan,
1)
# cumsum to group the rows
df['count']=df['count'].cumsum().ffill()
# groupby to take count of each group of rows and return groupsize using transform
df['count']=df.groupby('count')['col1'].transform('size')
df
col1 count
0 -5.0 3
1 -3.0 3
2 -7.0 3
3 4.0 2
4 5.0 2
5 -0.5 1
6 6.0 3
7 8.0 3
8 9.0 3
向計數值添加符號
df['count']=np.where(np.sign(df['col1']).diff().eq(0),
np.nan,
1)
df['count']=df['count'].cumsum().ffill()
df['count']=df.groupby('count')['col1'].transform('size')*np.sign(df['col1'])
df
col1 count
0 -5.0 -3.0
1 -3.0 -3.0
2 -7.0 -3.0
3 4.0 2.0
4 5.0 2.0
5 -0.5 -1.0
6 6.0 3.0
7 8.0 3.0
8 9.0 3.0
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標籤：熊猫