How do I average a time series with uneven intervals?

15 次查看（过去 30 天）
Anna
Anna 2013-6-28
Hi,
I have a time series which has vector values recorded at a frequency greater than 1 hz (1 measurement per second) with uneven intervals and I would like to average the vector values for each second so that I effectively have a time series with a 1 hz frequency.
Is it possible to create a loop with variable increments to achieve this? Or might ACCUMARRAY be more suitable?
Here is an example of my data set.
Time SO4 77237.3 0.165 77247.3 0.177 77276 0.137 77304.4 0.093 77304.4 0.093 77332.8 0.103 77361.3 0.072
Any help would be greatly appreciated. Thanks
  1 个评论
Anna
Anna 2013-6-28
编辑：Anna 2013-6-28
I didn't realise the example data I inserted had posted as linear text. I'm not sure how to rectify this so apologies but I hope it's clear that the 'Time' data is 77237.3, 77247.3, 77276.0 ...and the SO4 data is 0.165, 0.177, 0.137...

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Roger Stafford
Roger Stafford 2013-6-28
One possibility is to use 'interp1' set to interpolate at some appropriate multiple of one hertz, say, 20 Hz. You can select the type of interpolation that best suits your data. Read the documentation at
http://www.mathworks.com/help/matlab/ref/interp1.html
Then take a straightforward average over each twenty (or whatever multiple you choose) points to get the average for the corresponding second.
  1 个评论
Anna
Anna 2013-7-14
Thank you for your reply Roger Stafford! I have been trying to use 'interp1' but am still having some problems. I was able to use interp1 successfully for the above example because the two vectors were the same length.
I have another variable 'CCN' which has 9000 data points at a 1 hz frequency and I want to compare this to the 'Time' variable which has 300 data points. The range I am trying to compare in the two variables is from 77237 seconds (from 00 UTC) to 86357 seconds.
Here is my code: for k = 1:1:303 Time(end:end+numel(CCN)-numel(Time))=nan; CCN_new = interp1(Time,CCN,(77237:86357)) but I get the followig error message Error using griddedInterpolant The coordinates of the input points must be finite values; Inf and Nan are not permitted. Error in interp1>Interp1D (line 346) F = griddedInterpolant(Xext,V,method); Error in interp1 (line 241) Vq = Interp1D(X,V,Xq,method); Is there a way of making the vectors the same length without adding 'Nan' to the shorter one?
Please help if you can, Thanks

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Data Preprocessing 的更多信息

标签

Community Treasure Hunt

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

Start Hunting!

Translated by