Using the min and max function for form a new variable

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Farai Mwashita
Farai Mwashita 2014-10-27
评论： Farai Mwashita 2014-10-28
Hello
I am calculating HDD (heating degree days) and CDD (cooling degree days)and have managed to reshape the data to get a dailyT =reshape(data:,4)24,365). Now I need to use the min and max functions to create new variables (1 x 365) of daily min and max temperature and I am stuck on this stage.
Please can you assist on how to do this.
Regards
Farai

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回答（3 个）

Adam
Adam 2014-10-27
编辑：Adam 2014-10-27
If your data is (24,365) then you can just use the normal form:
dailyMins = min( data );
dailyMaxes = max( data );
to get (1,365)-sized results.
If you wanted to be explicit you can use:
dailyMins = min( data, [], 1 );
to tell min to calculate along dimension 1, thus returning a result of size equal to dimension 2, but since this is the default behaviour that is un-necessary. However, if your data happened to be (365,24) then you could use this method with a '2' as the final argument to achieve the same result.
Farai Mwashita
Farai Mwashita 2014-10-28
Hello Adam
Thank you for your help.
Farai Mwashita
Farai Mwashita 2014-10-28
hello
I have managed to calculate the average daily temperatures (1 x 365) and now I need to reshape this into monthly averages. I have been told the loop function can used, can you please assist on how to do so?
Regards
Farai
  2 个评论
Adam
Adam 2014-10-28
That is more than a reshape option, you would need to break down your 365 days into months, average each of these and then end up with a length 12 result.
e.g.
m = [31 28 31 30 31 30 31 31 30 31 30 31];
to give you the lengths of each month. Then a generic version of the following example:
monthlyAverage(1) = mean( dailyMins( 1:m(1) ) )
monthlyAverage(2) = mean( dailyMins( (m(1) + 1):( m(1) + m(2) ) ) );
etc, etc.
There are neater ways to do that of course in a generalised way than just writing out 12 hard-coded lines, but I'll leave that as an exercise for you.
You may find
cumsum( m );
to be very useful in simplifying the indexing into m.
Farai Mwashita
Farai Mwashita 2014-10-28
Hello
When i try to calculate for the second month, I get an error message saying unbalanced or enexpected parentesis or bracket. I can't seem to get past this stage.
Regards
Farai

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