使用merge()函数仅左键联接R中的选定列

问题描述

我正尝试左连接2个数据帧，但我不想连接第二个数据集中的所有变量:

I am trying to LEFT Join 2 data frames but I do not want join all the variables from the second data set:

例如，我有数据集1(DF1):

As an example, I have dataset 1 (DF1):

  Cl    Q   Sales  Date
   A    2   30     01/01/2014
   A    3   24     02/01/2014
   A    1   10     03/01/2014
   B    4   10     01/01/2014
   B    1   20     02/01/2014
   B    3   30     03/01/2014

我想离开联接数据集2(DF2):

And I would like to left join dataset 2 (DF2):

Client  LO  CON
   A    12  CA
   B    11  US
   C    12  UK
   D    10  CA
   E    15  AUS
   F    91  DD

我可以加入以下代码:

merge(x = DF1，y = DF2，by ="Client"，all.x = TRUE):

merge(x = DF1, y = DF2, by = "Client", all.x=TRUE) :

   Client Q    Sales   Date             LO      CON
   A      2    30      01/01/2014       12      CA
   A      3    24      02/01/2014       12      CA
   A      1    10      03/01/2014       12      CA
   B      4    10      01/01/2014       11      US
   B      1    20      02/01/2014       11      US
   B      3    30      03/01/2014       11      US

但是，它合并了LO和CON列.我只想合并LO列.

However, it merges both column LO and CON. I would only like to merge the column LO.

   Client Q    Sales   Date             LO      
   A      2    30      01/01/2014       12      
   A      3    24      02/01/2014       12      
   A      1    10      03/01/2014       12      
   B      4    10      01/01/2014       11      
   B      1    20      02/01/2014       11     
   B      3    30      03/01/2014       11      

推荐答案

您可以通过对传递到合并中的数据进行子设置来实现此目的:

You can do this by subsetting the data you pass into your merge:

merge(x = DF1, y = DF2[ , c("Client", "LO")], by = "Client", all.x=TRUE)

或者您也可以在当前合并后直接删除该列:)

Or you can simply delete the column after your current merge :)

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