fastacf: Fast Autocorrelation

In phonTools: Tools for Phonetic and Acoustic Analyses

Fast Autocorrelation

Description

Compute the ACF of a signal.

Usage

fastacf  (signal, lag.max = length(signal), window = 'hann',
          show = TRUE, correct = FALSE)

Arguments

signal	The signal, a numeric vector.
lag.max	The maximum lag value to be returned.
window	The type of window to be applied to the signal. Uses the windowfunc() function in this package. For no window select 'rectangular'.
show	If TRUE, the results are plotted.
correct	If TRUE, the output is corrected based on the window length and the window function that is applied.

Details

The autocorrelation function is calculated using the inverse Fourier transform applied to the power spectrum. This leads to much faster calculation times than the acf() function included in the typical R installation. Corrections for window type and length are carried out as described in Boersma (1993).

Value

A dataframe with the following columns:

lag	Indicates the lag value.
acf	Indicates the ACF value at the lag.

Author(s)

Santiago Barreda <[e-mail]>

References

Boersma, P., (1993). Accurate short-term analysis of the fundamental frequency and the harmonics-to-noise ratio of a sampled sound. Proc. Instit. Phon. Sci. 17: 97-110.

Examples

## Uncomment and run the code below to see the speed advantage.
## Raising the n makes the difference even more pronounced.
#n = 25000
#system.time ({
#acf (rnorm (n), plot = F, lag.max = n)
#})

#system.time ({
#fastacf (rnorm (n), plot = F, lag.max = n)
#})

phonTools documentation built on Nov. 21, 2023, 1:07 a.m.