Question

我假设我处理一个关于基于另一个列值（此处为患者）对数据进行子集化的简单问题，但无法找到解决方案。我需要为每位住院病人至少4次的数据子集。换句话说，只有在医院住过至少4次的患者才能在新的df中看到他们的4个访问行。我的表看起来像这样：

＆＃13;

</style>
<table class="tg">
  <tr>
    <th class="tg-yw4l">Patient</th>
    <th class="tg-yw4l"># Hospital Visits</th>
    <th class="tg-yw4l">Duration</th>
  </tr>
  <tr>
    <td class="tg-yw4l">Monica</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">10D</td>
  </tr>
  <tr>
    <td class="tg-yw4l">Jack</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">5D</td>
  </tr>
  <tr>
    <td class="tg-yw4l">Monica</td>
    <td class="tg-yw4l">2</td>
    <td class="tg-yw4l">3D</td>
  </tr>
  <tr>
    <td class="tg-yw4l">Eric</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">2D</td>
  </tr>
  <tr>
    <td class="tg-yw4l">Eric</td>
    <td class="tg-yw4l">2</td>
    <td class="tg-yw4l">3D</td>
  </tr>
  <tr>
    <td class="tg-yw4l">Monica</td>
    <td class="tg-yw4l">3</td>
    <td class="tg-yw4l">4D</td>
  </tr>
  <tr>
    <td class="tg-yw4l">Jack</td>
    <td class="tg-yw4l">2</td>
    <td class="tg-yw4l">4D</td>
  </tr>
  <tr>
    <td class="tg-yw4l">Eric</td>
    <td class="tg-yw4l">3</td>
    <td class="tg-yw4l">8D</td>
  </tr>
  <tr>
    <td class="tg-yw4l">Eric</td>
    <td class="tg-yw4l">4</td>
    <td class="tg-yw4l">9D</td>
  </tr>
</table>

＆＃13;

非常感谢！

Answer 1

df1 <- readHTMLTable(doc)[[1]]
colnames( df1 ) <- gsub("# ", '', colnames( df1 ))
df1$`Hospital Visits` <- as.numeric( df1$`Hospital Visits`)

df1
#   Patient Hospital Visits Duration
# 1  Monica               1      10D
# 2    Jack               1       5D
# 3  Monica               2       3D
# 4    Eric               1       2D
# 5    Eric               2       3D
# 6  Monica               3       4D
# 7    Jack               2       4D
# 8    Eric               3       8D
# 9    Eric               4       9D

仅获得患者至少4次去过医院的事件

with( df1, df1[ `Hospital Visits` >= 4, ] )
#   Patient  Hospital Visits Duration
# 9    Eric                4       9D

至少4次访问医院的患者的所有事件

do.call( 'rbind', lapply( split( df1, df1$Patient ), 
                          function( x ) if( any(x$'Hospital Visits' >= 4 ) ) { x }) )

#        Patient Hospital Visits Duration
# Eric.4    Eric               1       2D
# Eric.5    Eric               2       3D
# Eric.8    Eric               3       8D
# Eric.9    Eric               4       9D

数据：

library(XML) doc <- htmlParse('<table class="tg"> <tr> <th class="tg-yw4l">Patient</th> <th class="tg-yw4l"># Hospital Visits</th> <th class="tg-yw4l">Duration</th> </tr> <tr> <td class="tg-yw4l">Monica</td> <td class="tg-yw4l">1</td> <td class="tg-yw4l">10D</td> </tr> <tr> <td class="tg-yw4l">Jack</td> <td class="tg-yw4l">1</td> <td class="tg-yw4l">5D</td> </tr> <tr> <td class="tg-yw4l">Monica</td> <td class="tg-yw4l">2</td> <td class="tg-yw4l">3D</td> </tr> <tr> <td class="tg-yw4l">Eric</td> <td class="tg-yw4l">1</td> <td class="tg-yw4l">2D</td> </tr> <tr> <td class="tg-yw4l">Eric</td> <td class="tg-yw4l">2</td> <td class="tg-yw4l">3D</td> </tr> <tr> <td class="tg-yw4l">Monica</td> <td class="tg-yw4l">3</td> <td class="tg-yw4l">4D</td> </tr> <tr> <td class="tg-yw4l">Jack</td> <td class="tg-yw4l">2</td> <td class="tg-yw4l">4D</td> </tr> <tr> <td class="tg-yw4l">Eric</td> <td class="tg-yw4l">3</td> <td class="tg-yw4l">8D</td> </tr> <tr> <td class="tg-yw4l">Eric</td> <td class="tg-yw4l">4</td> <td class="tg-yw4l">9D</td> </tr> </table>')

Answer 2

无数种方法，一种简单的方式，虽然不是最有效的......

假设您在数据框中有此内容，则可以过滤掉具有4个或更多内容的ID（在本例中为名称）。然后显示这些名称的所有记录。我正在命名您的原始数据框my_df

who_to_include <- subset(unique(my_df$name),hospital_visits>=4)
library(dplyr)
4_or_more <- inner_join(who_to_include,my_df)

很抱歉，没有例子可以离开这里，所以我只是在这里代码，可能不是100％正确，或者可能是

Answer 3

假设您在数据框中有这个内容并且列＃34;患者＆＃34;唯一地指定患者（即没有多个Erics），您也可以仅使用基数R对其进行子集化：

# Find row numbers of entries with number of visits >= 4
frequentPatientRows <- patientsDf[, "# Hospital Visits"] >= 4
# Extract names from those rows
frequentPatientNames <- patientsDf[frequentPatientRows, "Name"]
# Select all entries for patients with those names
selectedPatients <- patientsDf[patientsDf[, "Name"] %in% frequentPatientNames, ]

R：基于另一列条目子集df

3 个答案: