19.1

19.1.md

@@ -1184,7 +1184,7 @@ df
 | 10 | Scouts | cavalry | veteran | Riani | 2 | 62 |
 | 11 | Scouts | cavalry | rookie | Ali | 3 | 70 |
 
-按公司和团对创建交叉表。按公司和团对计算观测数量。
+按公司和团队创建交叉表。按公司和团队计算观测数量。
 
 ```py
 pd.crosstab(df.regiment, df.company, margins=True)
@@ -1199,7 +1199,7 @@ pd.crosstab(df.regiment, df.company, margins=True)
 | All | 6 | 6 | 12 |
 
 ```py
-# 为每个团队创建一个新手和老兵骑兵和步兵士兵的交叉表
+# 为每个团队创建公司和经验的交叉表
 pd.crosstab([df.company, df.experience], df.regiment,  margins=True)
 ```
 
@@ -1207,9 +1207,9 @@ pd.crosstab([df.company, df.experience], df.regiment,  margins=True)
 | --- | --- | --- | --- | --- | --- |
 | company | experience |  |  |  |  |
 | cavalry | rookie | 1 | 1 | 1 | 3 |
-| veteran | 1 | 1 | 1 | 3 |
+| | veteran | 1 | 1 | 1 | 3 |
 | infantry | rookie | 1 | 1 | 1 | 3 |
-| veteran | 1 | 1 | 1 | 3 |
+| | veteran | 1 | 1 | 1 | 3 |
 | All |  | 4 | 4 | 4 | 12 |
 
 ## 删除重复
@@ -2105,8 +2105,6 @@ df.resample('D').median()
 | 2014-05-09 | 24941.5 | 32082.5 |
 | 2014-05-10 | 26067.5 | 37195.0 |
 
-### Aggregate into days by taking the first value of each day’s worth of hourly observation
-
 ```py
 # 对每小时观测值取第一个值来按天汇总
 df.resample('D').first()