Removing negative values and one positive value from R dataframe - r

Question

I have a dataframe where one column is the amount spent. In the amount spent column there are the values for amount spent and also negative values for any returns. For example.
ID Store Spent
123 A 18.50
123 A -18.50
123 A 18.50
I want to remove the negative value then one of its positive counter parts - the idea is to only keep fully completed spend amounts so I can look at total spend.
Right now I am thinking something like this - where I have the data frame sorted by spend
if spend < 0 {
take absolute value of spend
if diff between abs(spend) and spend+1 = 0 then both are NA}
I would like to have something like
df[df$spend < 0] <- NA
where I can also set one positive counterpart to NA as well. Any suggestions?

Answer 1

There should be a simpler solution to this but here is one way. Also created my own example since the one shared did not have sufficient data points to test
#Original vector
x <- c(1, 2, -2, 1, -1, -1, 2, 3, -4, 1, 4)
#Count the frequency of negative numbers, keeping all the unique numbers
vals <- table(factor(abs(x[x < 0]), levels = unique(abs(x))))
#Count the frequency of absolute value of original vector
vals1 <- table(abs(x))
#Subtract the frequencies between two vectors
new_val <- vals1 - (vals * 2 )
#Recreate the new vector
as.integer(rep(names(new_val), new_val))
#[1] 1 2 3

Answer 2

If you add a rowid column you can do this with data.table ant-joins.
Here's an example which takes ID into account, not deleting "positive counterparts" unless they're the same ID
First create more interesting sample data
df <- fread('
ID Store Spent
123 A 18.50
123 A -18.50
123 A 18.50
123 A -19.50
123 A 19.50
123 A -99.50
124 A -94.50
124 A 99.50
124 A 94.50
124 A 94.50
')
Now remove all the negative values with positive counterparts, and remove those counterparts
negs <- df[Spent < 0][, Spent := -Spent][, rid := rowid(ID, Spent)]
pos <- df[Spent > 0][, rid := rowid(ID, Spent)]
pos[!negs, on = .(ID, Spent, rid), -'rid']
# ID Store Spent rid
# 1: 123 A 18.5 2
# 2: 124 A 99.5 1
# 3: 124 A 94.5 2
And as applied to Ronak's x vector example
x <- c(1, 2, -2, 1, -1, -1, 2, 3, -4, 1, 4)
negs <- data.table(x = -x[x<0])[, rid := rowid(x)]
pos <- data.table(x = x[x>0])[, rid := rowid(x)]
pos[!negs, on = names(pos), -'rid']
# x
# 1: 2
# 2: 3
# 3: 1

Answer 3

I used the following code.
library(dplyr)
store <- rep(LETTERS[1:3], 3)
id <- c(1:4, 1:3, 1:2)
expense <- runif(9, -10, 10)
tibble(store, id, expense) %>%
group_by(store) %>%
summarise(net_expenditure = sum(expense))
to get this output:
# A tibble: 3 x 2
store net_expenditure
<chr> <dbl>
1 A 13.3
2 B 8.17
3 C 16.6
Alternatively, if you wanted the net expenditure per store-id pairing, then you could use this code:
tibble(store, id, expense) %>%
group_by(store, id) %>%
summarise(net_expenditure = sum(expense))
I've approached your question from a slightly different perspective. I'm not sure that my code answers your question, but it might help.