boxclip {boxfilter}

Boxfilter Main Function

Description

Filters noise from data (e.g. heartrates) using x for x-axis data and y for y-axis, based on the proportion of neighbors of each point in a surrounding box of width and height (these may be determined automatically). It discards all data points that have less than a proportion of clipit neighbors.

Usage

boxclip (x=NULL,y,clipit=NULL,QI=NULL,width=NULL, height=NULL,
miny=min(y,na.rm=TRUE), maxy=max(y,na.rm=TRUE), plotit=TRUE, histo=FALSE)

Arguments

x

The x-axis of data, a datetime for example. Optional. If x=NULL x<-1:length(y) will be generated.

y

The y-axis of data, probably noisy. Required.

clipit

Optional. Y-values with less than a proportion of clipit neighbors will be discarded. If clipit is omitted it is set equal to the first trough in the neighbor proportion histogram.

ci

QI

Optional. An integer quality index for each data point.

width

Optional. The width of the box. If width is omitted it will be generated from floor(length(x)*0.01).

height

Optional. The height of the box. If height is omitted it will be generated from floor(mean(y,na.rm=T)/4).

miny

The minimum y-value expected. Anything below miny is discarded.

maxy

The maximum y-value expected. Anything above maxy is discarded.

plotit

Optional.If TRUE show a graph of the original and filtered data.

histo

Optional. If TRUE also show a histogram of the neighboring points.

Details

Boxfilter mimics the human criterion of self-similarity. Data points with many neighbors are more trustworthy.

Value

x

Original x-axis data

y

Original y-axis data

filtered

Filtered data. Discarded data points are set to NA.

neighbors

Proportion of neighbors of each point.

Note

To store only filtered data, use e.g.:

bc=boxclip (x,y) data=data.frame(x=bc$x, hrf=bc$filtered) data=na.omit(data) write.csv(data,file="myheartrates.csv")

Author(s)

Thomas Ruf ([e-mail])

See Also

clipview

Examples

data("wb_month")
data("ibex_hr")

x=wb_month$x
y=wb_month$hr


myclip=boxclip(x,y, histo=TRUE)
summary(myclip)

r=seq(1,28400,by=4) 
myclip=boxclip(ibex_hr$Time[r],ibex_hr$Heartrate[r],0.65)
summary(myclip)
#store(myclip)


data("sleepduration")
Date=as.POSIXct(sleepduration$Date)
Duration=as.numeric(sleepduration$Bedtime)
boxclip(Date,Duration,miny=0)