How to create for loop on date?

Question

Behrooz Daneshian 2023-1-14

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https://ww2.mathworks.cn/matlabcentral/answers/1894180-how-to-create-for-loop-on-date

编辑： Star Strider 2023-1-15

Hi all,

Suppose that I have a table having two columns(variables). The first column is date and the second one is daily tempretaure. How can I make a for loop on dates? (e.g. lets say from september 2019 to April 2020, do this task on tempretaure column).

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Answer 1

Star Strider 2023-1-14

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https://ww2.mathworks.cn/matlabcentral/answers/1894180-how-to-create-for-loop-on-date#answer_1148865

编辑：Star Strider 2023-1-15

在 MATLAB Online 中打开

If you want to simply isolate the dates from September 2019 to April 2020, ise the isbetween function (or logical indexing, essentially what the function does). You can then copy them to a separate table to work with them. No loop is required.

EDIT — (15 Jan 2023 ar 1:19)

Perhaps something like this —

LD = load(websave('Table','https://www.mathworks.com/matlabcentral/answers/uploaded_files/1264110/Table.mat'));

Table = LD.Table

Table = 4842×2 table

date TAVG _______________________ ____ {'2001-04-01T00:00:00'} 45 {'2001-04-02T00:00:00'} 50 {'2001-04-03T00:00:00'} 59 {'2001-04-04T00:00:00'} 61 {'2001-04-05T00:00:00'} 61 {'2001-04-06T00:00:00'} 61 {'2001-04-07T00:00:00'} 64 {'2001-04-08T00:00:00'} 71 {'2001-04-09T00:00:00'} 65 {'2001-04-10T00:00:00'} 69 {'2001-04-11T00:00:00'} 65 {'2001-04-12T00:00:00'} 69 {'2001-04-13T00:00:00'} 60 {'2001-04-14T00:00:00'} 60 {'2001-04-15T00:00:00'} 66 {'2001-04-16T00:00:00'} 56

Table.date = datetime(Table.date, 'InputFormat','yyyy-MM-dd''T''HH:mm:ss', 'Format','yyyy-MM-dd HH:mm:ss')

Table = 4842×2 table

date TAVG ___________________ ____ 2001-04-01 00:00:00 45 2001-04-02 00:00:00 50 2001-04-03 00:00:00 59 2001-04-04 00:00:00 61 2001-04-05 00:00:00 61 2001-04-06 00:00:00 61 2001-04-07 00:00:00 64 2001-04-08 00:00:00 71 2001-04-09 00:00:00 65 2001-04-10 00:00:00 69 2001-04-11 00:00:00 65 2001-04-12 00:00:00 69 2001-04-13 00:00:00 60 2001-04-14 00:00:00 60 2001-04-15 00:00:00 66 2001-04-16 00:00:00 56

Select = isbetween(Table.date, datetime(2019,09,01), datetime(2020,04,3));

figure

plot(Table{Select,1}, Table{Select,2})

grid

xlim([min(Table{Select,1}) max(Table{Select,1})])

xlabel('Date & Time')

ylabel('T_{AVG}')

.

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Answer 2

Walter Roberson 2023-1-14

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S = dateshift(datetime('now') - days(300), 'start', 'day')
S = datetime
   20-Mar-2022
for D = S : calmonths(1) : S + calmonths(5)
    D
end
D = datetime
   20-Mar-2022
D = datetime
   20-Apr-2022
D = datetime
   20-May-2022
D = datetime
   20-Jun-2022
D = datetime
   20-Jul-2022
D = datetime
   20-Aug-2022

However...

If you are wanting to loop over months for grouping purposes, then much of the time it is easier to convert the table to a timetable and then use retime .

Or, alternately, to use ymd to extract year and month, use caldiff to calculate months relative to the ear, after which you can findgroups