Can u use filtfilt with structfun?

Question

Simon Hoffmann 2021-8-11

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https://ww2.mathworks.cn/matlabcentral/answers/896147-can-u-use-filtfilt-with-structfun

评论： Simon Hoffmann 2021-8-11

I needed to segregate my signal due to noise in several parts of a long-term measuremt, which is why the remaining section have different lengths (which is why i am using a struct). Now i want to filter the signal parts with a cheby type 2 IIR filter, but i get the error:

"Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters."

% High-Pass filter with 0.4Hz Stopband-Frequency to remove the dc offset and trend from raw data
cheby_hp = designfilt('highpassiir', 'FilterOrder', 10, 'StopbandFrequency', 0.4, 'StopbandAttenuation', 80, 'SampleRate', 200);
% Detrend with IIR-HP filter
phases_struct_hp_filtered = structfun(@filtfilt(cheby_hp), phases_struct_appended,'UniformOutput', false);

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Answer 1

Rik 2021-8-11

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You need to use either a function handle, or create an anonymous function. Your syntax does neither. Try this modification.

% High-Pass filter with 0.4Hz Stopband-Frequency to remove the dc offset and trend from raw data
cheby_hp = designfilt('highpassiir', 'FilterOrder', 10, 'StopbandFrequency', 0.4, 'StopbandAttenuation', 80, 'SampleRate', 200);
% Detrend with IIR-HP filter
phases_struct_hp_filtered = structfun(@(x) filtfilt(cheby_hp,x), phases_struct_appended,'UniformOutput', false);

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Simon Hoffmann 2021-8-11

This works just fine, thank you for your fast reply!

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Answer 2

Chunru 2021-8-11

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/896147-can-u-use-filtfilt-with-structfun#answer_764682

在 MATLAB Online 中打开

cheby_hp = designfilt('highpassiir', 'FilterOrder', 10, 'StopbandFrequency', 0.4, 'StopbandAttenuation', 80, 'SampleRate', 200);
% Detrend with IIR-HP filter
phases_struct_appended.n1 = randn(70,1);
phases_struct_appended.n2 = randn(40,1);
phases_struct_hp_filtered = structfun(@(x)filtfilt(cheby_hp, x), phases_struct_appended,'UniformOutput', false);
phases_struct_hp_filtered
phases_struct_hp_filtered = struct with fields:
    n1: [70×1 double]
    n2: [40×1 double]