使用 mutate 创建新的数据列答案

【问题标题】：creating new data columns with mutate使用 mutate 创建新的数据列
【发布时间】：2017-08-04 23:57:53
【问题描述】：

使用以下数据：

data <- data.frame(Name=c("11C","11C","12C","12C","20D","20D"),
               PID=c("AD15E","AD15E","AA05D","AA05D","Z48J","Z48J"),
               Type=c("Home","Auto","Home","Auto","Home","Auto"),
               Brand=c("A","B","C","H","I","D"),
               Model=c("A152","K235","W54","H2","A57","Y0878"))

使用 mutate，我想在第一个唯一 PID 显示的行上的数据框中创建四个新列（HomeBrand、HomeModel、AutoBrand、AutoModel）。

结果应如下所示：

result <- data.frame(Name=c("11C","12C","20D"),
               PID=c("AD15E","AA05D","Z48J"),
               Type=c("Home","Home","Home"),
               HomeBrand=c("A","C","I"),
               HomeModel=c("A152","W54","A57"),
               AutoBrand=c("B","H","D"),
               AutoModel=c("K235","H2","Y0878"))

我尝试过使用 mutate 但似乎无法弄清楚

【问题讨论】：

标签： r dplyr

【解决方案1】：

在结果中包含 Home 的 Type 列没有意义，因为 Type 列转到标题，并且对于每一行，您混合了 Home 和 Auto 值；没有那个专栏，reshape 的任务很简单：

reshape(data, idvar = c("Name", "PID"), timevar = "Type", direction = "wide") 

#  Name   PID Brand.Home Model.Home Brand.Auto Model.Auto
#1  11C AD15E          A       A152          B       K235
#3  12C AA05D          C        W54          H         H2
#5  20D  Z48J          I        A57          D      Y0878

为了比较，这是你的结果：

result
#  Name   PID Type HomeBrand HomeModel AutoBrand AutoModel
#1  11C AD15E Home         A      A152         B      K235
#2  12C AA05D Home         C       W54         H        H2
#3  20D  Z48J Home         I       A57         D     Y0878

【讨论】：

【解决方案2】：

我们可以通过dcast 做到这一点

library(data.table)
dcast(setDT(data), Name + PID  ~ Type, value.var = c("Brand", "Model"), sep="")
#   Name   PID BrandAuto BrandHome ModelAuto ModelHome
#1:  11C AD15E         B         A      K235      A152
#2:  12C AA05D         H         C        H2       W54
#3:  20D  Z48J         D         I     Y0878       A57

【讨论】：