I feel this should be easy in base R but I just can't figure it out.
I have a simple dataframe, let's say it looks like this

```
tbl <-  read.table(text = 
    "Field1 Field2
    100 200
    150 180
    200 160
    280 250
    300 300
    300 250",
header = TRUE)

```

Now, what I want to do is create a function that will apply a rolling % addition, something like:

```
fn <- function(tbl, pct) {}

```

which accepts the dataframe above as `tbl`. It adds a percentage fraction of the current row to the NEXT row down based on `pct`, and rolls this almost in a cumulative fashion.

For example, `fn(tbl$Field1, 0.1)` would generate the following results:

```
100   (100 + 0.1*0)
160   (150 + 0.1*100 = 160)
216   (200 + 0.1*160 = 216)
301.6 (280 + 0.1*216 = 301.6)

```

etc.

I'd use a package solution, but would prefer base R as it helps with the learning process! My longer term goal is to build a process the loops through each combination of field and pct so I can test it's effect in a regression model; hence my gut feel is that a function I can later apply is the way forward.

Thanks.