Dear Miluji,
I went through different combinations,
and find it elegant to sum the values
with respect to ID + High/Low Date
levels like if this was a list of
Dose/Material/Group experiments:
x[x$Date %in% c(4143, 4147),"j"] <-
tapply(x$Value, paste0(x$ID,
ife
Dear Miluji,
something like this could help:
sapply(tapply(x$Value, x$ID, cumsum),
function(x) x[seq(4, length(x), by=4)] - c(0, x[head(seq(4,
length(x), by=4), -1)]))
1.) Step 1:
Compute the cumsum for each ID:
tapply(x$Value, x$ID, cumsum)
2.) Step 2:
- iterate over the resulting
-Original Message-
From: R-help On Behalf Of Miluji Sb
Sent: Sunday, December 19, 2021 1:32 PM
To: r-help mailing list
Subject: [R] Sum every n (4) observations by group
Dear all,
I have a dataset (below) by ID and time sequence. I would like to sum every
four observations by ID.
I am
Dear Peter,
Thanks so much for your reply and the code! This is helpful.
What I would like is the data.frame below - sum values for *4140, 4141,
4142, 4143 *and then for *4144, 4145, 4146, 4147 *for IDs A, B, and C. Does
that make sense? Thanks again!
Best.
Milu
results <- structure(list(ID =
I'm not sure I understand the task, but if I do, assuming your data
frame is assigned to a variable named df, I would do something like
sumNs = function(x, n)
{
if (length(x) %%n !=0) stop("Length of 'x' must be a multiple of 'n'.")
n1 = length(x)/n
ind = rep(1:n1, each = n)
tapply(x,
Dear all,
I have a dataset (below) by ID and time sequence. I would like to sum every
four observations by ID.
I am confused how to combine the two conditions. Any help will be highly
appreciated. Thank you!
Best.
Milu
## Dataset
structure(list(ID = c("A", "A", "A", "A", "A", "A", "A", "A",
"B
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