Question

我得到了一个如下数据框。我想用总步数来创建一个新列。我有一张下面的桌子。您可以看到ID 1有5个步骤。

+----+--------------------------------------------------------+
| ID |                         Steps                          |
+----+--------------------------------------------------------+
|  1 | <DIV><P>Another step</P></DIV><DIV><P>A step</P></DIV> |
|    | <DIV><P>Another step</P></DIV><DIV><P>A step</P></DIV> |
|    | <DIV><P>Another step</P></DIV><DIV><P>A step</P></DIV> |
|    | <DIV><P>Another step</P></DIV><DIV><P>A step</P></DIV> |
|    | <DIV><P>Another step</P></DIV><DIV><P>A step</P></DIV> |
|  2 | <DIV><P>Another step</P></DIV>                         |
|    | <DIV><P>Something</P></DIV>                            |
|    | <DIV><P>Something</P></DIV>                            |
|    | <DIV><P>Something</P></DIV>                            |
|    | <DIV><P>Something</P></DIV>                            |
+----+--------------------------------------------------------+

我想使用“ DIV”通过正确的ID来计算步骤总数，并在步骤总数中添加一个新列。

+----+--------------------------------------------------------+-------------+
| ID |                         Steps                          | Total_Steps |
+----+--------------------------------------------------------+-------------+
|  1 | <DIV><P>Another step</P></DIV><DIV><P>A step</P></DIV> |          10 |
|    | <DIV><P>Another step</P></DIV><DIV><P>A step</P></DIV> |             |
|    | <DIV><P>Another step</P></DIV><DIV><P>A step</P></DIV> |             |
|    | <DIV><P>Another step</P></DIV><DIV><P>A step</P></DIV> |             |
|    | <DIV><P>Another step</P></DIV><DIV><P>A step</P></DIV> |             |
|  2 | <DIV><P>Another step</P></DIV>                         |           5 |
|    | <DIV><P>Something</P></DIV>                            |             |
|    | <DIV><P>Something</P></DIV>                            |             |
|    | <DIV><P>Something</P></DIV>                            |             |
|    | <DIV><P>Something</P></DIV>                            |             |
|  3 | <DIV><P>Just a step</P></DIV>                          |           4 |
|    | <DIV><P>Just a step</P></DIV>                          |             |
|    | <DIV><P>Just a step</P></DIV>                          |             |
|    | <DIV><P>Just a step</P></DIV>                          |             |
+----+--------------------------------------------------------+-------------+

Answer 1

将Series.str.count与GroupBy.transform和sum一起使用：

df['Total_Steps'] = df['Steps'].str.count('<DIV>').groupby(df['ID'].ffill()).transform('sum')
print (df)
   ID                                              Steps  Total_Steps
0   1  <DIV><P>Another step</P></DIV><DIV><P>A step</...           10
1   1  <DIV><P>Another step</P></DIV><DIV><P>A step</...           10
2   1  <DIV><P>Another step</P></DIV><DIV><P>A step</...           10
3   1  <DIV><P>Another step</P></DIV><DIV><P>A step</...           10
4   1  <DIV><P>Another step</P></DIV><DIV><P>A step</...           10
5   2                     <DIV><P>Another step</P></DIV>            5
6   2                        <DIV><P>Something</P></DIV>            5
7   2                        <DIV><P>Something</P></DIV>            5
8   2                        <DIV><P>Something</P></DIV>            5
9   2                        <DIV><P>Something</P></DIV>            5

如果仅需要第一个值，请在numpy.where上加上Series.duplicated：

s = df['Steps'].str.count('<DIV>').groupby(df['ID'].ffill()).transform('sum')
df['Total_Steps'] = np.where(df['ID'].duplicated(), np.nan, s)
#possible mixed values - numeric with empty strings, but then some function should failed
#df['Total_Steps'] = np.where(df['ID'].duplicated(), '', s)
print (df)
   ID                                              Steps  Total_Steps
0   1  <DIV><P>Another step</P></DIV><DIV><P>A step</...         10.0
1   1  <DIV><P>Another step</P></DIV><DIV><P>A step</...          NaN
2   1  <DIV><P>Another step</P></DIV><DIV><P>A step</...          NaN
3   1  <DIV><P>Another step</P></DIV><DIV><P>A step</...          NaN
4   1  <DIV><P>Another step</P></DIV><DIV><P>A step</...          NaN
5   2                     <DIV><P>Another step</P></DIV>          5.0
6   2                        <DIV><P>Something</P></DIV>          NaN
7   2                        <DIV><P>Something</P></DIV>          NaN
8   2                        <DIV><P>Something</P></DIV>          NaN
9   2                        <DIV><P>Something</P></DIV>          NaN

Answer 2

为什么不这样：

df['Total_Steps']=df['steps'].str.contains('\<Div\>\<P\>').count()

如何计算记录中的某些行，并用总计数创建新列？

2 个答案: