# GrowthRates

##### Calculates growth rates (AGR, PGR, RGRdiff) between pairs of values in a vector

Calculates either the Absolute Growth Rate (AGR), Proportionate Growth
Rate (PGR) or Relative Growth Rate (RGR) between pairs of time points,
the second of which is `lag`

positions before the first.
in `x`

.

##### Usage

```
AGRdiff(x, time.diffs, lag=1)
PGR(x, time.diffs, lag=1)
RGRdiff(x, time.diffs, lag=1)
```

##### Arguments

- x
A

`numeric`

from which the growth rates are to be calculated.- time.diffs
a

`numeric`

giving the time differences between successive values in`x`

.- lag
A

`integer`

specifying, for the second value in the pair to be operated on, the number positions it is ahead of the current value.

##### Details

The AGRdiff is calculated as the difference between a pair of values divided by the `time.diffs`

.
The PGR is calculated as the ratio of a value to a second value which is `lag`

values
ahead of the first in `x`

and the ratio raised to the
power of the reciprocal of `time.diffs`

.
The RGRdiff is calculated as the `log`

of the PGR and so is equal to the difference between
the logarithms of a pair of values divided by the `time.diffs`

.
The differences and ratios are obtained using `calcLagged`

with `lag = 1`

.

##### Value

A `numeric`

containing the growth rates which is the same length as `x`

and in which the first `lag`

values `NA`

.

##### See Also

`intervalGRaverage`

, `intervalGRdiff`

, `splitContGRdiff`

, `splitSplines`

, `calcLagged`

##### Examples

```
# NOT RUN {
data(exampleData)
longi.dat$Area.AGR <- with(longi.dat, AGRdiff(Area, time.diffs = Days.diffs))
# }
```

*Documentation reproduced from package growthPheno, version 1.0-13, License: GPL (>= 2)*