Question

让我回答一下我的问题，我如何按行对数字求和，并列出最后一列的总和，形成一个新的列，如第二个表（sum = a + b + c + d + e）？

而且我也想知道如果某些值是N / A，我还能将它们视为数字吗？

示例输入：

     a          b           c          d            e
1    90         67          18         39           74
2    100        103         20         45           50 
3    80         87          23         44           89
4    95         57          48         79           90
5    74         81          61         95           131

期望的输出：

     a          b           c          d            e    sum
1    90         67          18         39           74   288
2    100        103         20         45           50   318
3    80         87          23         44           89   323
4    95         57          48         79           90   369
5    74         81          61         95           131  442

Answer 1

要添加行总和，您可以使用addmargins

M <- matrix(c(90,67,18,39,74), nrow=1)
addmargins(M, 2)   #2 = row margin
#      [,1] [,2] [,3] [,4] [,5] [,6]
# [1,]   90   67   18   39   74  288

如果您缺少数据，则需要将边距函数更改为能够正确处理NA值的内容

M<-matrix(c(90,67,18,NA,74), nrow=1)
addmargins(M, 2, FUN=function(...) sum(..., na.rm=T))
#      [,1] [,2] [,3] [,4] [,5] [,6]
# [1,]   90   67   18   NA   74  249

Answer 2

考虑使用apply（）。例如：

set.seed(10) # optional, but this command will replicate data as shown

# create some data
x <-matrix(rnorm(1:25),nrow=5,ncol=5) # 5x5 matrix of random numbers
x
            [,1]       [,2]       [,3]        [,4]       [,5]
[1,]  0.01874617  0.3897943  1.1017795  0.08934727 -0.5963106
[2,] -0.18425254 -1.2080762  0.7557815 -0.95494386 -2.1852868
[3,] -1.37133055 -0.3636760 -0.2382336 -0.19515038 -0.6748659
[4,] -0.59916772 -1.6266727  0.9874447  0.92552126 -2.1190612
[5,]  0.29454513 -0.2564784  0.7413901  0.48297852 -1.2651980

x.sum <-apply(x,1,sum) # sum the rows. Note: apply(x,2,sum) sums cols

x.sum
[1]  1.003356605 -3.776777904 -2.843256446 -2.431935624 -0.002762636

# attach new column (x.sum) to matrix x  
x.sum.1 <-cbind(x,x.sum)

x.sum.1
                                                                    x.sum
[1,]  0.01874617  0.3897943  1.1017795  0.08934727 -0.5963106  1.003356605
[2,] -0.18425254 -1.2080762  0.7557815 -0.95494386 -2.1852868 -3.776777904
[3,] -1.37133055 -0.3636760 -0.2382336 -0.19515038 -0.6748659 -2.843256446
[4,] -0.59916772 -1.6266727  0.9874447  0.92552126 -2.1190612 -2.431935624
[5,]  0.29454513 -0.2564784  0.7413901  0.48297852 -1.2651980 -0.002762636

Answer 3

假设您拥有数据帧df，那么您可以尝试执行以下操作：

# Assuming the columns a,b,c,d,e are at indices 1:5
df$sum = rowSums(df[ , c(1:5)], na.rm = T)

或者您也可以尝试以下方法：

transform(df, sum=rowSums(df), na.rm = T)

R中的行数和

3 个答案: