R: Plotting of dynamic time warp results: pointwise comparison

dtwPlotTwoWay {dtw} | R Documentation

## Plotting of dynamic time warp results: pointwise comparison

### Description

Display the query and reference time series and their alignment, arranged for visual inspection.

### Usage

    dtwPlotTwoWay(d,xts=NULL,yts=NULL, offset=0,
    			ts.type="l",pch=21,
                            match.indices=NULL,
    			match.col="gray70", match.lty=3,
    			xlab="Index", ylab="Query value",
    			... )

### Arguments

`d` | an alignment result, object of class `dtw`
`xts` | query vector
`yts` | reference vector
`xlab,ylab` | axis labels
`offset` | displacement between the timeseries, summed to reference
`match.col, match.lty` | color and line type of the match guide lines
`match.indices` | indices for which to draw a visual guide
`ts.type,pch` | graphical parameters for timeseries plotting, passed to `matplot`
`...` | additional arguments, passed to `matplot`

### Details

The two vectors are displayed via the `matplot` functions; their appearance can be customized via the `type` and `pch` arguments (constants or vectors of two elements). If `offset` is set, the reference is shifted vertically by the given amount; this will be reflected by the right-hand axis.

Argument `match.indices` is used to draw a visual guide to matches; if a vector is given, guides are drawn for the corresponding indices in the warping curve (match lines). If integer, it is used as the number of guides to be plotted. The corresponding style is customized via the `match.col` and `match.lty` arguments.

If `xts` and `yts` are not supplied, they will be recovered from `d`, as long as it was created with the two-argument call of `dtw` with `keep.internals=T`. Only single-variate time series can be plotted this way.

### Warning

The function is incompatible with mechanisms for arranging plots on a device: `par(mfrow)`, `layout` and `split.screen`.

### Note

When `offset` is set values on the left axis only apply to the query.

### Author(s)

Toni Giorgino

### See Also

`dtwPlot` for other dtw plotting functions, `matplot` for graphical parameters.

### Examples

    ## A noisy sine wave as query
    ## A cosine is for reference; sin and cos are offset by 25 samples

    idx<-seq(0,6.28,len=100);
    query<-sin(idx)+runif(100)/10;
    reference<-cos(idx)
    dtw(query,reference,step=asymmetricP1,keep=TRUE)->alignment;

    ## Equivalent to plot(alignment,type="two");
    dtwPlotTwoWay(alignment);

    ## Highlight matches of chosen QUERY indices. We will do some index
    ## arithmetics to recover the corresponding indices along the warping
    ## curve

    hq <- (0:8)/8
    hq <- round(hq*100)      #  indices in query for  pi/4 .. 7/4 pi

    hw <- (alignment$index1 %in% hq)   # where are they on the w. curve?
    hi <- (1:length(alignment$index1))[hw];   # get the indices of TRUE elems

    ## Beware of the reference's y axis, may be confusing
    plot(alignment,offset=-2,type="two", lwd=3, match.col="grey50",
         match.indices=hi,main="Match lines shown every pi/4 on query");

    legend("topright",c("Query","Reference (rt. axis)"), pch=21, col=1:6)

[Package dtw version 1.18-1 Index]