# warpArea

From dtw v1.21-3
by Toni Giorgino

##### Compute Warping Path Area

Compute the area between the warping function and the diagonal (no-warping) path, in unit steps.

- Keywords
- ts

##### Usage

`warpArea(d)`

##### Arguments

- d
an object of class

`dtw`

##### Details

Above- and below- diagonal unit areas all count *plus* one (they do not
cancel with each other). The "diagonal" goes from one corner to the other
of the possibly rectangular cost matrix, therefore having a slope of
`M/N`

, not 1, as in `slantedBandWindow()`

.

The computation is approximate: points having multiple correspondences are averaged, and points without a match are interpolated. Therefore, the area can be fractionary.

##### Value

The area, not normalized by path length or else.

##### Note

There could be alternative definitions to the area, including considering the envelope of the path.

##### Examples

```
# NOT RUN {
ds<-dtw(1:4,1:8);
plot(ds);lines(seq(1,8,len=4),col="red");
warpArea(ds)
## Result: 6
## index 2 is 2 while diag is 3.3 (+1.3)
## 3 3 5.7 (+2.7)
## 4 4:8 (avg to 6) 8 (+2 )
## --------
## 6
# }
```

*Documentation reproduced from package dtw, version 1.21-3, License: GPL (>= 2)*

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