[R] Plotting accumulated data

[David Winsemius]

On Jan 28, 2011, at 3:07 PM, Ottar Kvindesland wrote:

> Hello all
>
> I have the data frame with this:
>
>             ID              DATETIME     TRN      TRN_S
> 1 1192756 2010-06-23 15:39:07 13.420 0.2236667
> 2 1192757 2010-06-23 15:40:07 13.805 0.2300833
> 3 1192758 2010-06-23 15:41:07 13.860 0.2310000
> 4 1192759 2010-06-23 15:42:07 13.750 0.2291667
> 5 1192760 2010-06-23 15:43:07 13.530 0.2255000
> 6 1192761 2010-06-23 15:44:07 13.805 0.2300833
>
> Now, I would like to plot a graph with DATETIME and the accumulated
> TRN_S.
>
> I can run a while loop like this:
>
> accumulated_trns <- 0
> last_value <-length(data$TRN_S)
> while (i < last_value) {
> acc_trns <- acc_trns + data$TRN_S[i]
> data$accumulated_trns[i] <- acc_trns
> i <- i + 1
> }
> data$accumulated_trns[i] <- acc_trns
> plot(data$DATETIME, data$accumulated_trns)

Perhaps:

plot(data$DATETIME, cumsum(data$TRN_S) )

Can probably also be generalized to cumulative sums within IDs using  
ave() or tapply().


>
>
> This is slow and demanding on the computer.
>
> There must be a better way to accumulate values! Any suggestion  
> greatly
> appreciated.
>
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>
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David Winsemius, MD
West Hartford, CT