Graph error with Periodogram, incorrect plotting

1 次查看（过去 30 天）

Mini Me 2014-5-20

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/130406-graph-error-with-periodogram-incorrect-plotting

评论： dpb 2014-5-21

I have this portion of code, my goal is to have my data go from 1200 x 1 to 300 by 4 and then reshape back into a []x 1 matrix. my problem is when i change the matrix to 300 x 4 then take the periodogram...since my Fs is 5, w for each column is now 0 to 2.5 hz which is fine for a 300 x4 matrix. when i make everything back to [] x 1 matrix, since size of w is 300 x4 it keeps repeating 0 to 2.5 4 times. i want the value for w to be continuous since my FS is 5 for the whole data. the periodogram give me four diff graphs instead of one. here's my code. Help

   New_Pxx=[];
    New_w=[];
  test=Downsampled_data(:);
New_array=reshape(test,(length(test)/length(timerArray)),length(timerArray));
   for i=1:4
    Fs=5;
    [Pxx w]=periodogram(test,[],'onesided',[],Fs);
New_Pxx=[New_Pxx;Pxx];
        New_w=[New_w;w]
 end
loglog(New_w,New_Pxx);

10 个评论
显示 8更早的评论隐藏 8更早的评论

dpb 2014-5-21

编辑：dpb 2014-5-21

在 MATLAB Online 中打开

That's still then same vector four times as test is a column vector of size(numel(test),1). It would, in fact, error on the second pass thru the loop on an indexing error.

Slow down, write a script or enter some commands at the command line interactively that actually work to demonstrate precisely what you're trying to do.

Then explain what it is that you think it means to do so and what's different than what you are getting.

ADDENDUM:

OK, on reflection with the first posting and the follow-on, maybe I'm able to fill in the blanks...

Fs=5;
test=reshape(Downsampled_data(:),length(test)/length(timerArray),[]);
for i=1:4
  [Pxx w]=periodogram(test(:,i),[],'onesided',[],Fs);
  New_Pxx=[New_Pxx;Pxx];
  New_w=[New_w;w];
end

That will at least run; it'll give four separate periodograms over the sections of the whole time series that will be similar or not depending on the stationarity of the signal with time.

Now I still don't understand what you expect the frequency associated with those to be other than that from 0 to half-Nyquist for each--that's what you've computed.

Mini Me 2014-5-21

never mind i fix the problem....Thank you for responding...

dpb 2014-5-21

And the problem fix was????

请先登录，再进行评论。

请先登录，再回答此问题。

回答（0 个）

请先登录，再回答此问题。

类别

Gaming Just for fun

在 Help Center 和 File Exchange 中查找有关 Just for fun 的更多信息

产品

MATLAB

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by

Graph error with Periodogram, incorrect plotting

10 个评论
显示 8更早的评论隐藏 8更早的评论

回答（0 个）

另请参阅

类别

标签

产品

Community Treasure Hunt

Graph error with Periodogram, incorrect plotting

10 个评论 显示 8更早的评论隐藏 8更早的评论

回答（0 个）

另请参阅

类别

标签

产品

Community Treasure Hunt

10 个评论
显示 8更早的评论隐藏 8更早的评论