R check equality of one column to rowSums of other columns

Question

I have a dataframe like this:

x	x1	x2	x3
1	1	0	0
0	3	0	0
2	0	0	2
1	0	1	0

I want to find rows that x=x1+x2+x3 and rows that y=y1+y2+y3. Here is my code to check x=x1+x2+x3:

col_x = c(3,5,7)
df[df$x == rowSums(df[col_x])]

Suppose return row 1,3,4, but it returned

  x x1 y1 x2 x3 y3
1 1  1  0  0  0  0
2 0  3  0  0  0  0
3 2  0  0  0  2  0
4 1  0  0  1  0  0

I also tried

col_x = c(3,5,7)
df[df$x == apply(df[col_x],1,sum)]

Which also give me:

  x x1 y1 x2 x3 y3
1 1  1  0  0  0  0
2 0  3  0  0  0  0
3 2  0  0  0  2  0
4 1  0  0  1  0  0

I can't figure out why it returned all rows and it had skip column y2.

score 1 · Answer 1 · answered Aug 07 '22 at 14:28

1

A possible solution:

library(dplyr)

df %>% 
  filter(x == rowSums(across(matches("x\\d$"))) &
    y == rowSums(across(matches("y\\d$"))))

#>   x y x1 y1 x2 y2 x3 y3
#> 1 1 0  1  0  0  0  0  0
#> 2 2 0  0  0  0  0  2  0
#> 3 1 0  0  0  1  0  0  0

answered Aug 07 '22 at 14:28

PaulS

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1

That's a nice work around too! – xiaochuan fang Aug 07 '22 at 14:38

score 1 · Accepted Answer · answered Aug 07 '22 at 14:35

1

You are just missing a comma.

col_x = c(3,5,7)
df[df$x == rowSums(df[col_x]),]

  x y x1 y1 x2 y2 x3 y3
1 1 0  1  0  0  0  0  0
3 2 0  0  0  0  0  2  0
4 1 0  0  0  1  0  0  0

answered Aug 07 '22 at 14:35

stomper

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I can't beleive that's the correct answer! – xiaochuan fang Aug 07 '22 at 14:37

R check equality of one column to rowSums of other columns

2 Answers2