How to determine values between two points and two times?

I want to determine the values between two measurements and between two dates (with 1-day interval) . For example, the dates are (15th to 30th of August 2018) and the measurements are (-9 to -12).

Thanks!

[dpb]

See documentation for timeseries object for selecting between dates and logical addressing or indexing for the values. Is two-liner once create the timeseries object.

[Ayman Alharbi]

Thanks. This is a first time using Matlab. Would you please providing an example how I can do that?

Answer 1

[dpb]

<Subscript-into-times-of-timetable> illustrates the time range.

Logical addressing on variables is simply writing the expression wanted..<Logical array indexing>

>> x=randi([-20 0],1,10)
x =
   -16   -17   -20   -18    -8    -1   -13   -12     0    -1
>> ix=(x>=-12 & x<=-9)
ix =
  1×10 logical array
   0   0   0   0   0   0   0   1   0   0
>> x(ix)
ans =
   -12
>> 

So, if you have a timetable tt, then

it=timerange('2018-08-15','2018-08-30');
ix=(x>=-12 & x<=-9);
tt2=tt.x(it,ix);

Example w/ a made up small data set; you can play with the TMW examples...

>> tt=timetable(datetime(t),rand(size(t)));     % just happened to have t hanging around
>> tt.Properties.VariableNames={'x'}            % variable name to real variable
tt =
  4×1 timetable
        Time          x   
    ___________    _______
    01-Dec-1981    0.66238
    03-Jan-1983    0.24417
    23-May-1990    0.29551
    17-Jun-2012    0.68018
>> it=timerange('01-Jan-1983','31-Dec-1993')    % make up a date range vector
it = 
	timetable timerange subscript:
		Select timetable rows with times in the half-open interval:
		[01-Jan-1983 00:00:00, 31-Dec-1993 00:00:00)
	See Select Timetable Data by Row Time and Variable Type.
>> ix=tt.x>=0.2 & tt.x<=0.3                     % now the variable loookup vector
ix =
  4×1 logical array
   0
   1
   1
   0
>> tt.x(it,ix)                   % and select the subset wanted...
ans =
    0.2442
    0.2955
>>

For the logical expression rather than having to write the compound expression I have a little "syntactic sugar" utility routine that lets one write it as single line and makes use in expression or as subscript expression much more legible to read and simpler to write:

function flg=iswithin(x,lo,hi)
% returns T for values within range of input
% SYNTAX:
%  [log] = iswithin(x,lo,hi)
%      returns T for x between lo and hi values, inclusive

  flg= (x>=lo) & (x<=hi);
>> 

Place in an m-file named iswithin.m somewhere on your MATLABPATH and then can write

ix=iswithin(tt.x,0.2,0.3);

or

tt.x(timerange('01-Jan-1983','31-Dec-1993'),iswithin(tt.x,0.2,0.3))

and eliminate the temporary variables if not needed elsewhere.

[Ayman Alharbi]

Thank you so much!

[dpb]

If this solves the problem, please ACCEPT Answer to indicate topic closed to others if nothing else...