필터 지우기
필터 지우기

Insert new rows of NaN for missing timestamps in time series.

조회 수: 16 (최근 30일)
Eric Escoto
Eric Escoto 2019년 1월 31일
답변: Peter Perkins 2019년 2월 7일
Hello, I have a time series that is missing some data. In the places where there is a data gap I would like to insert rows of NaN values at the same incremetal time step. The data is organized by a datenum.
Here is the current script I'm using to get the timeseries.
Thanks!
% Read the data.
[num, txt, raw] = xlsread('SFL_2018.xlsx'); % Creates three variables. A number (double), raw (cell), and txt (cell).
% Note that the 'txt' and 'raw' variables contain the decriptions of the columns.
% Rename the numerical matrix and remove the upper 4 rows that originally contained the data headers.
SFL2018 = num(5:end, :);
% Change the first column (excel datenum value) to MATLAB datenum value.
datevec = datetime(SFL2018(:,1),'ConvertFrom','excel');
date_num = datenum(datevec);
SFL2018 = [date_num SFL2018(:, 2:end)];
% Rename the 'txt' cell to 'header' and clear unused variables.
header = txt(1:4,:);
clearvars('num', 'txt', 'raw', 'date_num');

채택된 답변

Peter Perkins
Peter Perkins 2019년 2월 7일
retime "adjusts" your data to a new set of row times. In general, "adjust" means things like interpolate, or aggregate, or take the neaest value, but by default it fiills with missing values. So
>> tt = timetable([1;2;5;6],'RowTimes',datetime(2019,2,[1;2;5;6]))
tt =
4×1 timetable
Time Var1
___________ ____
01-Feb-2019 1
02-Feb-2019 2
05-Feb-2019 5
06-Feb-2019 6
>> retime(tt,datetime(2019,2,1:6))
ans =
6×1 timetable
Time Var1
___________ ____
01-Feb-2019 1
02-Feb-2019 2
03-Feb-2019 NaN
04-Feb-2019 NaN
05-Feb-2019 5
06-Feb-2019 6
Or in this simple case
>> retime(tt,'daily')
ans =
6×1 timetable
Time Var1
___________ ____
01-Feb-2019 1
02-Feb-2019 2
03-Feb-2019 NaN
04-Feb-2019 NaN
05-Feb-2019 5
06-Feb-2019 6

추가 답변 (1개)

Peter Perkins
Peter Perkins 2019년 1월 31일
I recommend you use a timetable. Read your data in using readtable, then use table2timetable. The retime function makes what you want one line.
  댓글 수: 1
Eric Escoto
Eric Escoto 2019년 2월 1일
Thanks, Peter
This method doesn't seem to create new rows and insert them into the SFL2018 array, creating a new array. If it does, I don't quite get how that would happen. Could you provide an example?
-Eric

댓글을 달려면 로그인하십시오.

카테고리

Help CenterFile Exchange에서 Dates and Time에 대해 자세히 알아보기

Community Treasure Hunt

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

Start Hunting!

Translated by