Question

我有一个如下所示的数据集：

set.seed(1234)
DT<-data.table(id=c(rep(c("a","b","c","d"),5)),
           year=rep(seq(from = 2010.5,to=2012.5,by = .5),each=4),
           value=rnorm(20,10,1))
DT
     id   year     value
 1:  a 2010.5  8.792934
 2:  b 2010.5 10.277429
 3:  c 2010.5 11.084441
 4:  d 2010.5  7.654302
 5:  a 2011.0 10.429125
 6:  b 2011.0 10.506056
 7:  c 2011.0  9.425260
 8:  d 2011.0  9.453368
 9:  a 2011.5  9.435548
10:  b 2011.5  9.109962
11:  c 2011.5  9.522807
12:  d 2011.5  9.001614
13:  a 2012.0  9.223746
14:  b 2012.0 10.064459
15:  c 2012.0 10.959494
16:  d 2012.0  9.889715
17:  a 2012.5  9.488990
18:  b 2012.5  9.088805
19:  c 2012.5  9.162828
20:  d 2012.5 12.415835

我想为每个ID添加3个相似的列，value_previous_6m，value_previous_y和value_next_y。第10行应如下所示：

id   year    value value_previous_6m value_previous_y value_next_y
b  2011.5  9.109962    10.50606         10.27743        9.088805

我想避免使用plyr函数，因为总数据集非常大。

非常感谢，添

编辑：我知道可以使用合并功能完成：

set.seed(1234)
DT<-data.table(id=c(rep(c("a","b","c","d"),5)),
           year=rep(seq(from = 2010.5,to=2012.5,by = .5),each=4),
           value=rnorm(20,10,1))
DT6mp <- copy(DT)
DT12mp <- copy(DT)
DT6mp[,year:=year-.5]
setkey(DT6mp,id,year);setkey(DT,id,year);setnames(DT6mp,"value","value6mp")
DT <- merge(DT,DT6mp,all.x=T,all.y=F,allow.cartesian=T)
DT12mp[,year:=year-1]
setkey(DT12mp,id,year);setkey(DT,id,year);setnames(DT12mp,"value","value12mp")
DT <- merge(DT,DT12mp,all.x=T,all.y=F,allow.cartesian=T)
DT

但我认为应该有更好的方法。

Answer 1

You can use this approach ( I voluntary did not aggregated the 3 columns addition to make it clearer):

    <style> .block1 {
      color: #0000ff;
      /*display: block;*/
      font-family: 宋体：SimSun font-size: 1.41667em;
      font-weight: bold;
      line-height: 1.2;
      margin-bottom: 0.67em;
      margin-left: 0;
      margin-right: 0;
      margin-top: 24pt;
      /* page-break-inside: avoid;*/
    }
    .calibre {
      color: #4F81BD;
      display: block;
      font-family: "細明體", sans-serif;
      font-size: 1em;
      margin-bottom: 0;
      margin-left: 5pt;
      margin-right: 5pt;
      margin-top: 0;
      padding-left: 0;
      padding-right: 0
    }
    .block2 {
      color: red;
      display: block;
      font-family: "細明體", sans-serif;
      margin-bottom: 3pt;
      margin-left: 0;
      margin-right: 0;
      margin-top: 3pt;
      padding-bottom: 0;
      padding-left: 0;
      padding-right: 0;
      padding-top: 0;
      text-align: justify
    }
    </style>

通过ID和时间在R中进行简单查找

1 个答案: