CODEWITHSUNDEEP
rcalculated-columns
Darpit Dave
Darpit Dave

Reputation: 71

How do I update the column values based on previous row values?

Dataframe looks like this:

Date        |   Length .

2005-01-01  -   3400 . 

2005-01-02  -    54000 .

2005-01-03  -     266450 .

2005-01-04  -     0 . 

2005-01-05  -     0 .

I want to break down the value in '266450' and distribute 86400 to the next row and if that value exceeds 86400 than pass the remaining to the next row again

For example, the answer should be this

Date        |   Length .

2005-01-01  -   3400 . 

2005-01-02  -    54000 .

2005-01-03  -     86400 .

2005-01-04  -     86400 . 

2005-01-05  -     86400 .

2005-01-06 -      7250

Upvotes: 1

Views: 136

Answers (1)

Chris Holbrook
Chris Holbrook

Reputation: 2636

A reproducible example would be helpful to understand the specific question, but I think the main and most interesting question here is how to "split" and "spread" a number over a vector. You can do this using integer quotient and remainder/modulus functions (%% and %/%). For example:

#function to split a number by some other number
# and spread the integer quotients and remainders
# over vector elements
split_and_spread <- function(x, BY){
 c(rep(BY, x %/% BY), x %% BY)
}

split_and_spread(266450, BY = 86400)
#[1] 86400 86400 86400  7250

and apply over a vector using (sapply and unlist)

x = c(3400, 54000, 266450)

#call with sapply and unlist
unlist(sapply(x, split_and_spread, BY = 86400))
#[1]  3400 54000 86400 86400 86400  7250

Upvotes: 1

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