Sum column with similar name - r

Question

I have a Dataset in R like this (my real dataset has more rows and columns):
AB1
AB3
AB4
XB1
XB3
XB4
12
34
0
5
3
7
I need to sum the column similar like
AB1+XB1 AB3+XB3 AB4+XB4
What is the code I can use?

Answer 1

You could use
library(dplyr)
df %>%
mutate(across(starts_with("AB"),
~.x + df[[gsub("AB", "XB", cur_column())]],
.names = "sum_{.col}"))
This returns
# A tibble: 1 x 9
AB1 AB3 AB4 XB1 XB3 XB4 sum_AB1 sum_AB3 sum_AB4
<dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
1 12 34 0 5 3 7 17 37 7
We use across and mutate in this approach.
First we select all columns starting with AB. The desired sums are always ABn + XB2, so we can use this pattern.
Next we replace AB in the name of the current selected column with XB and sum those two columns. These sums are stored in a new column prefixed with sum_.

Answer 2

Assuming it is the first character that changes and the others are used to group
df=read.table(text="
AB1 AB3 AB4 XB1 XB3 XB4
12 34 0 5 3 7
11 35 1 7 2 8",h=T)
sapply(
unique(substr(colnames(df),2,100)),
function(x){
rowSums(df[,grepl(x,colnames(df))])
}
)
B1 B3 B4
[1,] 17 37 7
[2,] 18 37 9

Answer 3

We can try the code below
cbind(
df,
list2DF(lapply(
split.default(df, gsub("\\D+", "", names(df))),
rowSums
))
)
which gives
AB1 AB3 AB4 XB1 XB3 XB4 1 3 4
1 12 34 0 5 3 7 17 37 7

Answer 4

Try this:
library(tidyverse)
tribble(
~AB1, ~AB3, ~AB4, ~XB1, ~XB3, ~XB4,
12, 34, 0, 5, 3, 7
) |>
pivot_longer(everything(), names_pattern = "(\\w\\w)(\\d)", names_to = c("prefix", "suffix")) |>
pivot_wider(names_from = prefix) |>
rowwise() |>
mutate(sum = sum(c_across(- suffix)))
#> # A tibble: 3 × 4
#> # Rowwise:
#> suffix AB XB sum
#> <chr> <dbl> <dbl> <dbl>
#> 1 1 12 5 17
#> 2 3 34 3 37
#> 3 4 0 7 7
Created on 2022-05-11 by the reprex package (v2.0.1)

Answer 5

If you know that structure is consistent (an "A" and "X" pair for everything), then this should work.
cols <- unique(substring(names(df), 2))
df[paste0("A", cols)] + df[paste0("X", cols)]

Answer 6

Using the 2 row DF2 in the Note as input calculate the suffixes (s), unique suffixes (u) and perform the indicated matrix multiplication giving (m). Finally convert that back to a data frame and set the names. No packages are used.
s <- substring(names(DF2), 2)
u <- unique(s)
m <- as.matrix(DF2) %*% outer(s, u, `==`)
sums <- setNames(as.data.frame(m), u); sums
## B1 B3 B4
## 1 17 37 7
## 2 17 37 7
If it is desired to append these as columns to DF2 then:
data.frame(DF2, sum = sums)
## AB1 AB3 AB4 XB1 XB3 XB4 sum.B1 sum.B3 sum.B4
## 1 12 34 0 5 3 7 17 37 7
## 2 12 34 0 5 3 7 17 37 7
Note
DF <- structure(list(AB1 = 12L, AB3 = 34L, AB4 = 0L, XB1 = 5L, XB3 = 3L,
XB4 = 7L), class = "data.frame", row.names = c(NA, -1L))
DF2 <- rbind(DF, DF)
DF2
## AB1 AB3 AB4 XB1 XB3 XB4
## 1 12 34 0 5 3 7
## 2 12 34 0 5 3 7

Answer 7

An option with across2 from dplyover
library(dplyover)
df1 %>%
mutate(across2(starts_with('AB'), starts_with('XB'),
~ .x + .y, .names = "sum_{xcol}"))
AB1 AB3 AB4 XB1 XB3 XB4 sum_AB1 sum_AB3 sum_AB4
1 12 34 0 5 3 7 17 37 7