MATLAB: How to average datetimes of the array

array2timetableaveraging times

I think this may be a simple problem so hopefully someone can help me!

I have datetime values for every 10 seconds of every day for a few years of black carbon values

I'd like to average these to hourly intervals, so that i can correlate this data with data from another array which is in 30 sec intervals

I'm sure i need to use array2timetable and make a timetable to average the data.

The time values are currently in date time format.

I'm attempting to do this on one day at first, this is my data in a table, i cant seem to get it in an array

mytable =

1182×2 table

x1 y1

____________________ ________

23-Jun-2017 10:43:50 4.6948

23-Jun-2017 10:44:00 27.012

23-Jun-2017 10:44:10 36.513

23-Jun-2017 10:44:20 15.741

23-Jun-2017 10:44:30 3.7222

23-Jun-2017 10:44:40 6.0609

23-Jun-2017 10:44:50 8.8386

23-Jun-2017 10:45:00 4.0301

23-Jun-2017 10:45:10 1.8601

23-Jun-2017 10:45:20 3.294

23-Jun-2017 10:45:30 2.7862

23-Jun-2017 10:45:40 2.0448

23-Jun-2017 10:45:50 2.5459

This is an example of what data looks like, for this day it runs from 10:00-14:00.

Thanks!

Best Answer

Look at the retime() function for a timetable.

Related Solutions

MATLAB: Filter only specific month from date serial number

Unless you're using a version prior to R2014b, use datetimes:

>> dn = 736696 + 90*rand(10,1)
dn =
          736755.016662924
          736699.214051072
          736772.421637528
          736780.059392298
          736757.086163937
          736764.196611752
          736762.881922131
          736731.300431758
          736754.993010116
          736711.406801903
>> d = datetime(dn,'ConvertFrom','datenum')
d = 
  10×1 datetime array
   01-Mar-2017 00:23:59
   04-Jan-2017 05:08:14
   18-Mar-2017 10:07:09
   26-Mar-2017 01:25:31
   03-Mar-2017 02:04:04
   10-Mar-2017 04:43:07
   08-Mar-2017 21:09:58
   05-Feb-2017 07:12:37
   28-Feb-2017 23:49:56
   16-Jan-2017 09:45:47
>> (d.Month == 3)
ans =
  10×1 logical array
   1
   0
   1
   1
   1
   1
   1
   0
   0
   0

Prior to 14b, use datevec.

MATLAB: Insert of discontinuous dates/time (yyyymmddhhmm) to the first column and filling of NAN to the second column which missing unknown field

In recent versions of MATLAB:

>> t = readtable('Tide.txt','ReadVariableNames',false);
>> t.Properties.VariableNames = {'Time' 'X' 'Y'}
t =
  11×3 table
          Time            X        Y  
    ________________    _____    _____
    23/08/2017 00:00        4    2.044
    23/08/2017 00:01    4.001    2.046
    23/08/2017 00:03    4.007     2.05
    23/08/2017 00:04    4.009    2.054
    23/08/2017 00:07    4.017    2.061
    23/08/2017 00:08    4.019    2.063
    23/08/2017 00:09    4.022    2.065
    23/08/2017 00:10    4.023    2.067
    23/08/2017 00:11    4.026    2.069
    23/08/2017 00:13    4.028    2.072
    23/08/2017 00:14     4.03    2.074
>> tt = table2timetable(t)
tt =
  11×2 timetable
          Time            X        Y  
    ________________    _____    _____
    23/08/2017 00:00        4    2.044
    23/08/2017 00:01    4.001    2.046
    23/08/2017 00:03    4.007     2.05
    23/08/2017 00:04    4.009    2.054
    23/08/2017 00:07    4.017    2.061
    23/08/2017 00:08    4.019    2.063
    23/08/2017 00:09    4.022    2.065
    23/08/2017 00:10    4.023    2.067
    23/08/2017 00:11    4.026    2.069
    23/08/2017 00:13    4.028    2.072
    23/08/2017 00:14     4.03    2.074
>> tt = retime(tt,'minutely')
tt =
  15×2 timetable
          Time            X        Y  
    ________________    _____    _____
    23/08/2017 00:00        4    2.044
    23/08/2017 00:01    4.001    2.046
    23/08/2017 00:02      NaN      NaN
    23/08/2017 00:03    4.007     2.05
    23/08/2017 00:04    4.009    2.054
    23/08/2017 00:05      NaN      NaN
    23/08/2017 00:06      NaN      NaN
    23/08/2017 00:07    4.017    2.061
    23/08/2017 00:08    4.019    2.063
    23/08/2017 00:09    4.022    2.065
    23/08/2017 00:10    4.023    2.067
    23/08/2017 00:11    4.026    2.069
    23/08/2017 00:12      NaN      NaN
    23/08/2017 00:13    4.028    2.072
    23/08/2017 00:14     4.03    2.074

Or perhaps even

>> tt = retime(tt,'minutely','spline')
tt =
  15×2 timetable
          Time            X         Y   
    ________________    ______    ______
    23/08/2017 00:00         4     2.044
    23/08/2017 00:01     4.001     2.046
    23/08/2017 00:02     4.004    2.0475
    23/08/2017 00:03     4.007      2.05
    23/08/2017 00:04     4.009     2.054
    23/08/2017 00:05    4.0116    2.0571
    23/08/2017 00:06    4.0145    2.0592
    23/08/2017 00:07     4.017     2.061
    23/08/2017 00:08     4.019     2.063
    23/08/2017 00:09     4.022     2.065
    23/08/2017 00:10     4.023     2.067
    23/08/2017 00:11     4.026     2.069
    23/08/2017 00:12    4.0275    2.0705
    23/08/2017 00:13     4.028     2.072
    23/08/2017 00:14      4.03     2.074

Prior to R2016b, you'd have to do without timetables, and you may have to convert the first column of that file from text to datetime after reading. But you can recreate the call to retime using interp1.

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