Question

我使用XAMPP设置了一个MySQL数据库，并且已经做了一些非常基本的事情。我尝试使用dbApply，只是为了复制R文档中的示例。但结果看起来并不正确。我期待结果是3项清单：4,6和8缸汽车的mpg百分位数。这是代码：

con <- dbConnect(RMySQL::MySQL(), host = "localhost",dbname="rbaseball"
         ,user = "root", password = "")
dbWriteTable(con, "mtcars", mtcars, overwrite = TRUE)
res <- dbSendQuery(con, "SELECT * FROM mtcars ORDER BY cyl") 
dbApply(res, INDEX="cyl", FUN = function(x,grp) {quantile(x$mpg)})

这是输出。这是一个30项的清单。对于除2个列表之外的所有列表，5个百分位数完全相同，表示在用于计算百分位数的数据向量中只有一个数字。这似乎不是R示例试图获得的输出。

$`4.000000`
  0%  25%  50%  75% 100% 
22.8 22.8 22.8 22.8 22.8 

$`4.000000`
  0%  25%  50%  75% 100% 
24.4 24.4 24.4 24.4 24.4 

$`4.000000`
  0%  25%  50%  75% 100% 
22.8 22.8 22.8 22.8 22.8 

$`4.000000`
  0%  25%  50%  75% 100% 
32.4 32.4 32.4 32.4 32.4 

$`4.000000`
  0%  25%  50%  75% 100% 
30.4 30.4 30.4 30.4 30.4 

$`4.000000`
  0%  25%  50%  75% 100% 
33.9 33.9 33.9 33.9 33.9 

$`4.000000`
  0%  25%  50%  75% 100% 
21.5 21.5 21.5 21.5 21.5 

$`4.000000`
  0%  25%  50%  75% 100% 
27.3 27.3 27.3 27.3 27.3 

$`4.000000`
  0%  25%  50%  75% 100% 
  26   26   26   26   26 

$`4.000000`
  0%  25%  50%  75% 100% 
30.4 30.4 30.4 30.4 30.4 

$`6.000000`
  0%  25%  50%  75% 100% 
21.0 21.1 21.2 21.3 21.4 

$`6.000000`
  0%  25%  50%  75% 100% 
  21   21   21   21   21 

$`6.000000`
  0%  25%  50%  75% 100% 
21.4 21.4 21.4 21.4 21.4 

$`6.000000`
  0%  25%  50%  75% 100% 
18.1 18.1 18.1 18.1 18.1 

$`6.000000`
  0%  25%  50%  75% 100% 
19.2 19.2 19.2 19.2 19.2 

$`6.000000`
  0%  25%  50%  75% 100% 
17.8 17.8 17.8 17.8 17.8 

$`8.000000`
   0%   25%   50%   75%  100% 
18.70 18.95 19.20 19.45 19.70 

$`8.000000`
  0%  25%  50%  75% 100% 
14.3 14.3 14.3 14.3 14.3 

$`8.000000`
  0%  25%  50%  75% 100% 
16.4 16.4 16.4 16.4 16.4 

$`8.000000`
  0%  25%  50%  75% 100% 
17.3 17.3 17.3 17.3 17.3 

$`8.000000`
  0%  25%  50%  75% 100% 
15.2 15.2 15.2 15.2 15.2 

$`8.000000`
  0%  25%  50%  75% 100% 
10.4 10.4 10.4 10.4 10.4 

$`8.000000`
  0%  25%  50%  75% 100% 
10.4 10.4 10.4 10.4 10.4 

$`8.000000`
  0%  25%  50%  75% 100% 
14.7 14.7 14.7 14.7 14.7 

$`8.000000`
  0%  25%  50%  75% 100% 
15.5 15.5 15.5 15.5 15.5 

$`8.000000`
  0%  25%  50%  75% 100% 
15.2 15.2 15.2 15.2 15.2 

$`8.000000`
  0%  25%  50%  75% 100% 
13.3 13.3 13.3 13.3 13.3 

$`8.000000`
  0%  25%  50%  75% 100% 
19.2 19.2 19.2 19.2 19.2 

$`8.000000`
  0%  25%  50%  75% 100% 
15.8 15.8 15.8 15.8 15.8 

$`8.000000`
  0%  25%  50%  75% 100% 
  15   15   15   15   15

R文档中的dbApply示例不起作用

0 个答案: