CODEWITHSUNDEEP
r
user1234440
user1234440

Reputation: 23567

R: Sum of Previous Elements

I have a vector called z:

x<-matrix(rep(-0.02,12))
y<-matrix(rep(0.03,12))

a<-rbind(x,y)
z<-cumprod(1+a) #

The initial point and the last point in the Z vector are 0.98 and 1.12. The length of the series is 24. The shortest distance between the two is by travelling in increments of:

(1.12 - 0.98) / (24-1) = 0.0060355

In order to get the series I must add 0.98 to 0.0060355 to get element 2. To get element 3, I must take element 2 and add 0.0060355. How can one do this most efficiently in R rather than a loop that requires looping and referencing the previous element? Is this possible?

Upvotes: 0

Views: 3149

Answers (3)

IRTFM
IRTFM

Reputation: 263331

Rather than calculating the increment, let seq do it for you:

seq(z[1], z[length(z)], length=length(z) )

Upvotes: 1

PAC
PAC

Reputation: 5366

One other solution would be to create a new vector w and to use the cumsum function :

w <- c(.98, rep(0.0060355,23)
cumsum(w)

Upvotes: 3

TooTone
TooTone

Reputation: 8126

It seems you want equally spaced intervals in your new sequence. In which case, I think you just want to use the seq command

seq(z[1],z[length(z)],(z[length(z)]-z[1])/(length(z)-1))

Upvotes: 1

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