Assuming John's understanding is correct, you can also do this without for loops. It takes getting used to vector and matrix arithmetic, which you can read more about in the Introduction to R document that comes with R, or on R Exercises website [1].

You indicated having a problem with my last reproducible example... it did work, if you went through it one step at a time. If you skipped steps, you would have problems like you encountered. For completeness, I will give the whole reproducible example again here... don't mix in your own steps until you have worked through all the steps in this example... or at least if you do, go back and step through these steps one at a time if you change something that breaks it.

[1] http://r-exercises.com/2015/11/28/matrix-exercises/

#########------ begin
rates <- read.table( text =
"Date          Int
Jan-1959        5
Feb-1959        5
Mar-1959        5
Apr-1959        5
May-1959        5
Jun-1959        5
Jul-1959        5
Aug-1959        5
Sep-1959        5
Oct-1959        5
Nov-1959        5
", header = TRUE, colClasses = c( "character", "numeric" ) )

rates$thisone <- c(diff(rates$Int), NA)
rates$nextone <- c(diff(rates$Int, lag=2), NA, NA)
rates$lastone <- (rates$thisone + rates$nextone)/6.5*1000

rates$experiment1 <- rates$Int + c( rates$Int[ -1 ], NA )
rates$Int2 <- (1:11)^2
rates$experiment2 <- rates$Int2 + c( rates$Int2[ -1 ], NA )

# lag
N <- 5
# see ?embed, or https://en.wikipedia.org/wiki/Embedding
embed( c( rates$Int2, rep( NA, N ) ), N+1 )
# make a matrix of the same size as the embed result
matrix( rep( rates$Int2, N+1 ), ncol=N+1 )
# subtract the first values
embed( c( rates$Int2, rep( NA, N ) ), N+1 ) - rates$Int2
# or can rely on automatic replication ... depends on the
# fact that the embed result is a matrix which is really just
# a vector displayed in folded up form
embed( c( rates$Int2, rep( NA, N ) ), N+1 ) - rates$Int2
# anyway, the result can be computed in one line (wrapped for readability)
rates$experiment3 <- rowSums(   embed( c( rates$Int2
                                        , rep( NA, N )
                                        )
                                     , N+1
                                     )
                              - rates$Int2
                            , na.rm=TRUE
                            )
rates
       Date Int thisone nextone lastone experiment1 Int2 experiment2 experiment3
1  Jan-1959   5       0       0       0          10    1           5          85
2  Feb-1959   5       0       0       0          10    4          13         115
3  Mar-1959   5       0       0       0          10    9          25         145
4  Apr-1959   5       0       0       0          10   16          41         175
5  May-1959   5       0       0       0          10   25          61         205
6  Jun-1959   5       0       0       0          10   36          85         235
7  Jul-1959   5       0       0       0          10   49         113         170
8  Aug-1959   5       0       0       0          10   64         145         110
9  Sep-1959   5       0       0       0          10   81         181          59
10 Oct-1959   5       0      NA      NA          10  100         221          21
11 Nov-1959   5      NA      NA      NA          NA  121          NA           0

#dput(rates)
result <- structure(list(Date = c("Jan-1959", "Feb-1959", "Mar-1959", "Apr-1959", "May-1959", "Jun-1959", "Jul-1959", "Aug-1959", "Sep-1959", "Oct-1959", "Nov-1959"), Int = c(5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5), thisone = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, NA), nextone = c(0, 0, 0, 0, 0, 0,
0, 0, 0, NA, NA), lastone = c(0, 0, 0, 0, 0, 0, 0, 0, 0, NA,
NA), experiment1 = c(10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
NA), Int2 = c(1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121), experiment2 = c(5, 13, 25, 41, 61, 85, 113, 145, 181, 221, NA), experiment3 = c(85,
115, 145, 175, 205, 235, 170, 110, 59, 21, 0)), .Names = c("Date",
"Int", "thisone", "nextone", "lastone", "experiment1", "Int2",
"experiment2", "experiment3"), row.names = c(NA, -11L), class = "data.frame")

#########------ end


On Sat, 24 Dec 2016, Fox, John wrote:

Dear Arthur,

Here's a simple script to do what I think you want. I've applied it to a 
contrived example, a vector of the squares of the integers 1 to 25, and have 
summed the first 5 differences, but the script is adaptable to any numeric 
vector and any maximum lag. You'll have to decide what to do with the last 
maximum-lag (in my case, 5) entries:

-------------- snip ------------
(x <- (1:25)^2)
[1]   1   4   9  16  25  36  49  64  81 100 121 144 169 196 225 256 289 324 361 
400 441 484 529 576
[25] 625
len <- length(x)
maxlag <- 5
diffs <- matrix(0, len, maxlag)
for (lag in 1:maxlag){
+     diffs[1:(len - lag), lag] <- diff(x, lag=lag)
+ }
head(diffs)
    [,1] [,2] [,3] [,4] [,5]
[1,]    3    8   15   24   35
[2,]    5   12   21   32   45
[3,]    7   16   27   40   55
[4,]    9   20   33   48   65
[5,]   11   24   39   56   75
[6,]   13   28   45   64   85
tail(diffs)
     [,1] [,2] [,3] [,4] [,5]
[20,]   41   84  129  176  225
[21,]   43   88  135  184    0
[22,]   45   92  141    0    0
[23,]   47   96    0    0    0
[24,]   49    0    0    0    0
[25,]    0    0    0    0    0
rowSums(diffs)
[1]  85 115 145 175 205 235 265 295 325 355 385 415 445 475 505 535 565 595 625 
655 450 278 143  49
[25]   0
-------------- snip ------------

The script could very simply be converted into a function if this is a 
repetitive task with variable inputs.

I hope this helps,
John

-----------------------------
John Fox, Professor
McMaster University
Hamilton, Ontario
Canada L8S 4M4
Web: socserv.mcmaster.ca/jfox



-----Original Message-----
From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of arthur
brogard via R-help
Sent: December 24, 2016 12:29 AM
To: Jeff Newmiller <jdnew...@dcn.davis.ca.us>
Cc: r-help@r-project.org
Subject: Re: [R] Is there a funct to sum differences?

Yes, sorry about that.  I keep making mistakes I shouldn't make.

Thanks for the tip about 'reply all', I had no idea.

You can ignore the finalone. I have been doing other work on this and it comes
from there. I took the example from the R screen after it had run one of these
other things that created the finalone.

I guess I was thinking just seeing the data mentioned in the code was be
enough.

I don't want a function to do the division and multiplication.

It's a function that will ".. automatically sum the difference between the first

 and subsequent to the end of a list? "  that I am looking for.

I will try to explain, I know I often don't make myself clear:

I'm using this diff() function.

This 'diff()' function finds the difference between two adjoining entries and it
applies itself to the whole list so that in an instant I can have a list of
differences between any two adjoining.

Then I can have a list of differences between any two with any specified gap -
'lag' it is called.
Using the same function.

Now I have them and do that.  Then I add them together to find the 'lastone'
which is the total difference for the period.


Now here's the point:  that covers a period of two timespans, months, they are.

 if I want to cover a span of 24 months, say, then I would have to write this
diff() function 24 times.

 what I'm doing is finding the difference between the starting point and every
other point and then adding them all together.  bit like finding the area
beneath the curve maybe.

 And that's what I want to do.

 :)









----- Original Message -----
From: Jeff Newmiller <jdnew...@dcn.davis.ca.us>
To: arthur brogard <abrog...@yahoo.com>
Cc: r-help@r-project.org
Sent: Saturday, 24 December 2016, 15:34
Subject: Re: [R] Is there a funct to sum differences?

You need to "reply all" so other people can help as well, and others can learn
from your questions.

I am still puzzled by how you expect to compute "finalone". If you had supplied
numbers other than all 5's it might have been easier to figure out what is going
on.

What is your purpose in performing this calculation?

#### reproducible code
rates <- read.table( text =
"Date          Int
Jan-1959        5
Feb-1959        5
Mar-1959        5
Apr-1959        5
May-1959        5
Jun-1959        5
Jul-1959        5
Aug-1959        5
Sep-1959        5
Oct-1959        5
Nov-1959        5
", header = TRUE, colClasses = c( "character", "numeric" ) )

#your code
rates$thisone <- c(diff(rates$Int), NA)
rates$nextone <- c(diff(rates$Int, lag=2), NA, NA) rates$lastone <-
(rates$thisone + rates$nextone)/6.5*1000 # I doubt there is a ready-built
function that knows you want to # divide by 6.5 or multiply by 1000

# form a vector from positions 2:11 and append NA)
rates$experiment1 <- rates$Int + c( rates$Int[ -1 ], NA ) # numbers that are not
all the same
rates$Int2 <- (1:11)^2
rates$experiment2 <- rates$Int2 + c( rates$Int2[ -1 ], NA )

# dput(rates)
result <- structure(list(Date = c("Jan-1959", "Feb-1959", "Mar-1959", "Apr-
1959", "May-1959", "Jun-1959", "Jul-1959", "Aug-1959", "Sep-1959", "Oct-
1959", "Nov-1959"), Int = c(5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5), thisone = c(0, 0, 
0, 0, 0,
0, 0, 0, 0, 0, NA), nextone = c(0, 0, 0, 0, 0, 0, 0, 0, 0, NA, NA), lastone = 
c(0, 0, 0,
0, 0, 0, 0, 0, 0, NA, NA), Int2 = c(1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121),
experiment1 = c(10, 10, 10, 10, 10, 10, 10, 10, 10, 10, NA), experiment2 = c(5,
13, 25, 41, 61, 85, 113, 145, 181, 221, NA)), .Names = c("Date", "Int",
"thisone", "nextone", "lastone", "Int2", "experiment1", "experiment2"),
row.names = c(NA, -11L), class = "data.frame")

On Sat, 24 Dec 2016, arthur brogard wrote:



Yes, sure, thanks for your interest.  I apologise for not submitting in the
correct manner.  I'll learn (I hope).

Here's the source - a spreadsheet with just two columns, date and 'Int'.


Date    Int
Jan-1959    5
Feb-1959    5
Mar-1959    5
Apr-1959    5
May-1959    5
Jun-1959    5
Jul-1959    5
Aug-1959    5
Sep-1959    5
Oct-1959    5
Nov-1959    5


After processing it becomes this:


rates
Date   Int thisone nextone     lastone finalone
1   1959-01-01  5.00    0.00    0.00    0.000000       10
2   1959-02-01  5.00    0.00    0.00    0.000000       10
3   1959-03-01  5.00    0.00    0.00    0.000000       10
4   1959-04-01  5.00    0.00    0.00    0.000000       10
5   1959-05-01  5.00    0.00    0.00    0.000000       10
6   1959-06-01  5.00    0.00    0.00    0.000000       10

The one long column I'm referring to is the 'Int' column which R has imported.

The actual code is:


rates <- read.csv("Rates2.csv",header =
TRUE,colClasses=c("character","numeric"))

sapply(rates,class)

rates$Date <- strptime(paste0("1-", rates$Date), format="%d-%b-%Y",
tz="UTC")


rates$thisone <- c(diff(rates$Int), NA) rates$nextone <-
c(diff(rates$Int, lag=2), NA, NA) rates$lastone <- (rates$thisone +
rates$nextone)/6.5*1000


rates



ab



----- Original Message -----
From: Jeff Newmiller <jdnew...@dcn.davis.ca.us>
To: arthur brogard <abrog...@yahoo.com>; arthur brogard via R-help
<r-help@r-project.org>; "r-help@r-project.org" <r-help@r-project.org>
Sent: Saturday, 24 December 2016, 13:25
Subject: Re: [R] Is there a funct to sum differences?

Could you make your example reproducible? That is, include some sample
input and output. You talk about a column of numbers and then you seem to
work with named lists and I can't reconcile your words with the code I see.
--
Sent from my phone. Please excuse my brevity.


On December 23, 2016 3:40:18 PM PST, arthur brogard via R-help <r-help@r-
project.org> wrote:
I've been looking but I can't find a function to sum difference.

I have this code:


rates$thisone <- c(diff(rates$Int), NA) rates$nextone <-
c(diff(rates$Int, lag=2), NA, NA) rates$lastone <- (rates$thisone +
rates$nextone)


It is looking down one long column of numbers.

It sums the difference between the first two and then between the
first and third and so on.

Can it be made to automatically sum the difference between the first
and subsequent to the end of a list?

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---------------------------------------------------------------------------
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______________________________________________
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https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.


---------------------------------------------------------------------------
Jeff Newmiller                        The     .....       .....  Go Live...
DCN:<jdnew...@dcn.davis.ca.us>        Basics: ##.#.       ##.#.  Live Go...
                                      Live:   OO#.. Dead: OO#..  Playing
Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
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______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

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