selecting columns with certain time period and placing in new array

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Sophie Stringer 2019-8-19

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评论： Bob Thompson 2019-8-20

mjo_data.mat

Hi there,

I have a data file ranging from 1974 to 2019 and I would like to select the data that corresponds to the period 2003/01/01 to 2009/12/31 and create another array (not sure if thats the right term).

Currently column 1,2 & 3 indicate year, month and day. But preferably would want to put this into a datenum() and create a serial date number.

If anyone has any idea how to this, any help would be greatly appreciated. I've attached the matlab file.

Kind regards,

Sophie

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Answer 1

Bob Thompson 2019-8-19

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In general, I would make an effort to extract the data using logic indexing. You can certainly convert the mdy into a datetime variable, but if you're looking to sort by each year it is not necessary.

I have not looked at your attached file (it's a limitation on my end), so the specific designations are probably off in the example. Adjust as needed.

data = mjo_data(mjo_data(:,1)==[2003:2009],:);
time = datetime(data(:,1:3))

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Sophie Stringer 2019-8-20

编辑：Sophie Stringer 2019-8-20

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Hi Bob,

Thanks for the help! I struggled to do it that way, I'm not entirley sure why, but kept getting an error message. I ended up doing it like this:

fname = 'Documents/Project/wh_index_clean2.txt';
MJO_data = load(fname);
 
% Select for data within 2003-2009 
MJO_2003_09 = MJO_data(MJO_data(:,1)>=2003 & MJO_data(:,1)<=2009, :);
 

Bob Thompson 2019-8-20

The error was likely because it was trying to find elements which matched the entire array, which is a logic error on my part. Your alternative solution would be correct.

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