Poincare Plot

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Description

The Poincare plot is a graphical representation of the dependance between successive RR intervals obtained by plotting the RR_(j+tau) as a function of RR_j. This dependance is often quantified by fitting an ellipse to the plot. In this way, two parameters are obtained: SD_1 and SD_2. SD_1 characterizes short-term variability whereas that SD_2 characterizes long-term variability.

Usage

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PoincarePlot(HRVData,
  indexNonLinearAnalysis = length(HRVData$NonLinearAnalysis), timeLag = 1,
  confidenceEstimation = FALSE, confidence = 0.95, doPlot = FALSE,
  main = "Poincare plot", xlab = "RR[n]", ylab = paste0("RR[n+", timeLag,
  "]"), pch = 1, cex = 0.3, type = "p", xlim = NULL, ylim = NULL, ...)

Arguments

HRVData

Data structure that stores the beats register and information related to it

indexNonLinearAnalysis

Reference to the data structure that will contain the nonlinear analysis

timeLag

Integer denoting the number of time steps that will be use to construct the dependance relation: RR_(j+timeLag) as a function of RR_j.

confidenceEstimation

Logical value. If TRUE, the covariance matrix is used for fitting the ellipse and computing the SD_1 and SD_2 parameters (see details). Default: FALSE.

confidence

The confidence used for plotting the confidence ellipse.

doPlot

Logical value. If TRUE (default), the PoincarePlot is shown.

main

An overall title for the Poincare plot.

xlab

A title for the x axis.

ylab

A title for the y axis.

pch

Plotting character (symbol to use).

cex

Character (or symbol) expansion.

type

What type of plot should be drawn. See plot.default.

xlim

x coordinates range. If not specified, a proper x range is selected.

ylim

y coordinates range. If not specified, a proper y range is selected.

...

Additional parameters for the Poincare plot figure.

Details

In the HRV literature, when timeLag = 1, the SD_1 and SD_2 parameters are computed using time domain measures. This is the default approach in this function if timeLag=1. This function also allows the user to fit a ellipse by computing the covariance matrix of (RR_(j),RR_(j+tau)) (by setting confidenceEstimation = TRUE). In most cases, both approaches yield similar results.

Value

A HRVData structure containing a PoincarePlot field storing the SD_1 and SD_2 parameters. The PoincarePlot field is stored under the NonLinearAnalysis list.

Examples

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## Not run: 
 data(HRVProcessedData)
 # rename for convenience
 hd = HRVProcessedData
 hd = CreateNonLinearAnalysis(hd)
 hd = PoincarePlot(hd, doPlot = T)

## End(Not run)

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