euler: Euler Character

Description Usage Arguments Value Author(s) References See Also Examples

View source: R/euler.R

Description

Mostly an for internal use in conjunction with resels. Calculates the euler characteristic at a threshold level.

Usage

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euler(u, df, fieldType)

Arguments

u

statistical value (typically the maxima of a cluster or statistical field)

df

degrees of freedom expressed as df = c(degrees of interest, degrees of error)

fieldType
  • T: T-field

  • F: F-field

  • X: Chi-square field'

  • Z: Gaussian field

Value

A vector of estimated euler characteristics for dimensions 0:D

Author(s)

Zachary P. Christensen

References

Worlsey K.J., (1996) A Unified Statistical Approach for Determining Significant Signals in Images of Cerebral Activation.

See Also

rftPval, resels

Examples

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mask <- getMask(  antsImageRead( getANTsRData( 'r16' )  ) )
myresels <- resels(mask, c(1, 1))
# pretend these results are from a t-statistical field fitted with 10 df to
# find a peak value.
df <- c(1, 10) # made up degrees of freedom
ec <- euler(4, df, fieldType = "T") # peak value is 4
ez <- euler(3, df, fieldType = "T") # we thresholded at 3
# uncorrected peak-level p-value
pvox <- sum(ec * myresels)/sum(ez * myresels)

neuroconductor/ANTsR documentation built on Oct. 11, 2020, 8:14 a.m.