如何添加列名相同的数据帧

Question

我有两个数据框df1和df2.我想创建一个新的数据帧df3是简单的总和df1,并df2在列名相同.

df1 <- data.frame(x1=c(1,4,5),x2=c(5,6,7),x3=c(9,9,10))
df2 <- data.frame(x1=c(1,6,3),x2=c(4,3,1),x3=c(5,4,6),x4=c(7,6,7))

 df1
    x1  x2  x3
 1  1   5   9
 2  4   6   9
 3  5   7   10

df2
    x1  x2  x3  x4
 1  1   4   5   7
 2  6   3   4   6
 3  3   1   6   7

df3
    x1  x2  x3  x4
 1  2   9   14  7
 2  10  9   13  6
 3  8   8   16  7

Answer 1

我们找到'df1'和'df2'('nm1')中常见的列名.创建'df2'('df3')的副本.添加数据集子集(df1[nm1],df2[nm1])并将其分配给'df3'的相应子集.

nm1 <- intersect(names(df1), names(df2))
df3 <- df2
df3[nm1] <- df1[nm1]+df2[nm1]
df3
#  x1 x2 x3 x4
#1  2  9 14  7
#2 10  9 13  6
#3  8  8 16  7

如果'df1'中的其他唯一列不在'df2'中,反之亦然,一个选项是将数据集放在a中list,然后rbind用rbindlist(from data.table)创建一个序列列('N')并使用lapply得到sum每个列的.

library(data.table)
rbindlist(list(df1, df2), fill=TRUE, idcol=TRUE)[,
       N:= 1:.N, .id][,lapply(.SD, sum, na.rm=TRUE) , 
           by = N , .SDcols=x1:x4][, N:= NULL][]
#   x1 x2 x3 x4
#1:  2  9 14  7
#2: 10  9 13  6
#3:  8  8 16  7