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Here is what to be coded in R:
sum_{n=1}^{10}\left(\frac{2^{n}}{n^2} + \frac{n^{4}}{4^{n}}\right)
With purrr I'd say something like:
sum(map_dbl(1:10, fun(x) 2^x/^2+x^4/4^x)
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how to add parentheses between numbers? I know how to add dashes, are they doing the same way? like 123456789 to (123)456789 in R programming?
sub("(\\d{3})", "(\\1)", 123456789)
[1] "(123)456789"
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I need to iterate a sequence that is being repeated.
Say I have a vector of 1,2,3 I want printed out 5 times.
each time needs to be inceased by one.
so 1,2,3,2,3,4,3,4,5,4,5,6,5,6,7
rep(1:3, 5) + rep(0:4, each=3)
should do the trick
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I have a vector c("A","B","C",......) and a list list(c("A"),c("B","C"))
I want to get a vector c(1,2,2....)
Is there any function in some basic packages?
we can use merge
merge(stack(setNames(lst, seq_along(lst))), data.frame(values=v1))$ind
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How can I achieve somethign like this in R:
like this?
vec <- runif(5)
plot(0,0,type="n",xlim=c(0,1.5),ylim=c(0,7),bty="n",axes="off")
at<-barplot(vec,horiz=TRUE,add=TRUE)
text(vec,at,signif(vec,1),pos=4)
text(rep(1,5),at,c("mn","lu","co","-","my"))
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Data sample is below: I have 3million rows.
Date,id,type,qty
9/30/14,1,’A’,10
9/30/14,2,’Z’,12
9/30/14,3,’B’,15
9/30/14,1,’B’,20
9/30/14,1,’Z’,20
9/30/14,1,’A’,20
9/30/14,2,’B’,20
9/30/14,3,’B’,5
9/30/14,3,’A’,40
I want result as below:
Date,id,type,Qty
9/30/14,1,A,20
9/30/14,1,B,20
9/30/14,2,B,20
9/30/14,3,B,5
9/30/14,3,’A’,40
Logic is below: On the same date, pick the latest qty (from the later record) for each id and type.Ignore types y and Z.
DT[,.(Qty=last(qty)),by=.(Date,id,type)][type!='Z'][order(id)]