https://github.com/baggepinnen/adaptivefilters.jl
Classical adaptive linear filters in Julia
Science Score: 13.0%
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Classical adaptive linear filters in Julia
Basic Info
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- Stars: 14
- Watchers: 2
- Forks: 4
- Open Issues: 1
- Releases: 3
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Metadata Files
README.md
AdaptiveFilters
Simple adaptive AR filters. We export two functions:
julia
yh = adaptive_filter(y, alg=MSPI; order=4, lr=0.1)
This filters y with an adaptive AR (only poles) filter with specified order and returns yh which is the predicted output from an adaptive line enhancer (ALE). If your noise is wideband and signal narrowband, yh is your desired filtered signal. If the noise is narrowband and the signal is wideband, then y-yh is your desired filtered signal.
Arguments:
- alg: Stochastic approximation algorithm or weight function. Examples: OMAP, MSPI, OMAS, ADAM, ExponentialWeight, EqualWeight. ExponentialWeight corresponds to the recursive least-squares algorithm (RLS). ADAM corresponds roughly to the normalized least-mean squares (NLMS) algorithm. More options exist if OnlineStats is loaded.
- y: Input signal
- order: Filter order
- lr: Learning rate or weight depending on alg
The function
julia
focused_adaptive_filter(y, band, fs, args...; kwargs...)
allows you to specify a frequency band (tuple) in which to focus the attention of the adaptive filter. fs here denotes the sample rate, e.g., 44100Hz.
Installation
julia
using Pkg; Pkg.add("AdaptiveFilters")
Demo app
```julia using AdaptiveFilters, Plots, Interact inspectdr() # Preferred plotting backend for waveforms
y = [sin.(1:100); sin.(0.2 .(1:100))] # A sinusoid with changing frequency yn = y .+ 0.1randn(length(y)) # A sinusoid with noise
function app(req=nothing) @manipulate for order = 2:2:10, lr = LinRange(0.01, 0.99, 100), alg = [ExponentialWeight, MSPI, OMAP, OMAS, ADAM] yh = adaptive_filter(yn, alg, order=order, lr=lr) e = yn.-yh plot([yn yh], lab=["Measured signal" "Prediction"], layout=(2,1), show=false, sp=1) plot!(e, lab="Error", sp=2, title="RMS: $(√mean(abs2, e))") end end
app()
Save filtered sound to disk
using WAV
yh = adaptive_filter(yn, OMAP, order=4, lr=0.25)
e = yn.-yh
wavwrite(e, "filtered.wav", Fs=fs)
```
NLMS
A normalized least-mean squares (NLMS) filter can be created like
julia
using AdaptiveFilters, Random
N = 60 # Number of filter taps
μ = 0.01 # Learning rate
f = NLMS(N, μ)
This filter can then be called like
ŷ, e = f(x, d)
where x is the input signal, d is the desired signal and ŷ is the filtered signal. The error e is also returned. This call modifies the internal state of f.
Adaptive line enhancer
The NLMS filter can be used to build an adaptive line enhancer (ALE) by letting the input signal be the desired signal delayed by a number of samples Δ:
```julia using Random Random.seed!(0) y = sin.(0:0.1:100) yn = y + 0.1*randn(length(y)) # A sinusoid with noise
T = length(y) YH = zeros(T) E = zeros(T)
Δ = 1 # Delay in samples
for i = eachindex(y) YH[i], E[i] = f(yn[max(i-Δ, 1)], yn[i]) end
using Plots, Test @test mean(abs2, y[end-100:end] - YH[end-100:end]) < 1e-3 plot([y yn YH E y-YH], lab=["y" "yn" "yh" "e" "y-yh"]) ```
Internals
This is a lightweight wrapper around functionality in OnlineStats.jl which does all the heavy lifting.
Usage from python
- First install Julia and install this package in Julia.
- Install pyjulia using their instructions.
- Now the following should work
```python $ python3
import julia from julia import AdaptiveFilters as af yh = af.adaptivefilter(y)
if that fails, try replacing the first line withpython from julia.api import Julia jl = Julia(compiledmodules=False) ```
Keyword args etc. work as normal
python
af.adaptive_filter(y, af.ADAM, order=2)
Example: Adaptive cicada filtering
The following function does a reasonable job at filtering out the sound of cicadas from an audio recording
julia
cicada_filter(y,fs,args...; kwargs...) = y-focused_adaptive_filter(data,(4200,11000),fs,args...; kwargs...)
Owner
- Name: Fredrik Bagge Carlson
- Login: baggepinnen
- Kind: user
- Location: Lund, Sweden
- Website: baggepinnen.github.io
- Twitter: baggepinnen
- Repositories: 59
- Profile: https://github.com/baggepinnen
Control systems, system identification, signal processing and machine learning
GitHub Events
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Last synced: 8 months ago
Top Committers
| Name | Commits | |
|---|---|---|
| Fredrik Bagge Carlson | b****n@g****m | 31 |
| github-actions[bot] | 4****] | 1 |
| Fredrik Bagge Carlson | b****n@g****m | 1 |
Committer Domains (Top 20 + Academic)
Issues and Pull Requests
Last synced: 6 months ago
All Time
- Total issues: 4
- Total pull requests: 3
- Average time to close issues: 3 days
- Average time to close pull requests: about 2 months
- Total issue authors: 3
- Total pull request authors: 2
- Average comments per issue: 3.25
- Average comments per pull request: 1.0
- Merged pull requests: 3
- Bot issues: 0
- Bot pull requests: 1
Past Year
- Issues: 0
- Pull requests: 0
- Average time to close issues: N/A
- Average time to close pull requests: N/A
- Issue authors: 0
- Pull request authors: 0
- Average comments per issue: 0
- Average comments per pull request: 0
- Merged pull requests: 0
- Bot issues: 0
- Bot pull requests: 0
Top Authors
Issue Authors
- baggepinnen (2)
- Sinansi (1)
- JuliaTagBot (1)
Pull Request Authors
- baggepinnen (2)
- github-actions[bot] (1)
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Packages
- Total packages: 1
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Total downloads:
- julia 3 total
- Total dependent packages: 0
- Total dependent repositories: 0
- Total versions: 3
juliahub.com: AdaptiveFilters
Classical adaptive linear filters in Julia
- Documentation: https://docs.juliahub.com/General/AdaptiveFilters/stable/
- License: MIT
-
Latest release: 0.1.2
published over 2 years ago
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