Can one extract a unit of time from a duration object?

Some of my programs of data analysis produce 'duration' objects, and I am looking for a way of printing them as strings.

I have the option of guessing an appropriate unit of time from data, then calling a (relatively unnatural) instruction like:

sprintf("%.2f sec",seconds(T2print))

Relatively unexpectedly, both "char" and "string" operators' results seem to depend on how the object has been initially created, as the following code shows.

Tsec = seconds(1)
%->  duration
%   1 sec

Tmin = minutes(1)
%->  duration
% "1 min"

isequal(60*Tsec,Tmin)
%true !

string(60*Tsec)
% "60 sec"

char(60*Tsec)
%'60 sec'

string(Tmin)
%"1 min"

char(Tmin)
%'1 min'

It is certainly possible to parse the output of "string", then to extract the unit of time, but I would like to find a simpler way of finding it. Getting identical results for equal durations would obviously be a positive point.

My question is related to this one:

Is it possible to convert a duration array to something else like a number or string?

Thanks for your attention!

Answer 1

[Steven Lord]

MATLAB will try to select a good format for the duration object based on the data with which it was created. But if you want all your duration objects to have a consistent format, you can specify it.

s = seconds(60)

s = duration
   60 sec

formatForSeconds = s.Format

formatForSeconds = 's'

m = minutes(1)

m = duration
   1 min

formatForMinutes = m.Format

formatForMinutes = 'm'

Let's change the format for m to be the same as the format for s.

m.Format = formatForSeconds

m = duration
   60 sec

Now that they're using the same format, converting them to text data will give the same text data.

sString = string(s)

sString = "60 sec"

mString = string(m)

mString = "60 sec"

isequal(sString, mString)

ans = logical
   1

See the section about the Format property of duration objects on the duration documentation page for a list of available format components.

[Alexandre Aksenov]

Thanks for pointing to the Format property!

This is the exact tool, which is necessary for my needs. Indeed, the property 'Format' allows to build a general instruction, specifying the number of significative digits, and using the appropriate unit of time for any given duration.

On the contrary, the example instruction, which I tried (see the original question) does not answer the problem, precisely because it tries to express any duration in seconds.

Answer 2

[Lei Hou]

Hi Alexandre,

Applying seconds/minutes/... to a duration array returns numeric value

>> d1 = seconds(60)

d1 = 

  duration

   60 sec

>> d2 = minutes(1)

d2 = 

  duration

   1 min

>> x1 = seconds(d1)

x1 =

    60

>> x2 = seconds(d2)

x2 =

    60

>> isequal(seconds(d1),seconds(d2))

ans =

  logical

   1
   
   

Hoping this is helpful.

Thanks,

Lei

[Alexandre Aksenov]

Thanks for your attention!

I am currently using the function 'seconds' to convert any statistic of my data befire printing. This works precisely as you suggest! This approach is sufficient when it has been checked in advance, that the data is of the order of magnitude of seconds.