我有
| ColA | ColB |
|---|---|
| A | 01 |
| A | 02 |
| B | 03 |
| B | 04 |
| C | 05 |
| D | NaN |
如果使用
df.ColA.value_counts()
结果是
| ColA | |
|---|---|
| A | 2 |
| B | 2 |
| C | 1 |
| D | 1 |
我怎样才能得到
| ColA | |
|---|---|
| A | 2 |
| B | 2 |
| C | 1 |
| D | 0 |
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用途：
s = df.dropna(subset=['ColB']).ColA.value_counts().reindex(df.ColA.unique(), fill_value=0)
print (s)
ColA
A 2
B 2
C 1
D 0
Name: count, dtype: int64