## determine index of a value (monthly) from excel table

さんによって質問されました 2018 年 2 月 25 日

さんによって コメントされました 2018 年 3 月 4 日
KSSV

### KSSV (view profile)

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Hi.. how i can determine index monthly mean for time series each years i have ponit every houer so in one day i have 24 points and each month i have difrrent number of points , like Jan 24x31=744 , Feb 24x28=672... I find some months incomplete

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### KSSV (view profile)

on 25 Feb 2018

Convert your dates to date vectors....it gives month values too....from these days vecs you can pick the months you want..read about datevec.

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on 1 Mar 2018
code datevec ... useful thanks

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### Peter Perkins (view profile)

on 26 Feb 2018

If you are using R2016b or later, use a timetable, and call retime to compute a monthly mean. Even prior to 16b, you should use a table with a datetime variable in it, and use varfun to compute the mean with month as the grouping variable.

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on 1 Mar 2018
may you give me example
example table in my work
Peter Perkins

### Peter Perkins (view profile)

2018 年 3 月 1 日
Your example spreadsheet has data from one month. But in any case, all you need is readtable, table2timetable, and retime.
Warning: Variable names were modified to make them valid MATLAB identifiers. The original names are saved in the
VariableDescriptions property.
t =
18×3 table
Jday Datetime WL_m_
______ ____________________ _____
0.0417 01-Jan-2008 00:00:00 4.42
0.0833 01-Jan-2008 01:00:00 4.17
0.125 01-Jan-2008 02:00:00 3.95
0.1667 01-Jan-2008 03:00:00 3.76
0.2083 01-Jan-2008 04:00:00 3.61
0.25 01-Jan-2008 05:00:00 3.6
0.2917 01-Jan-2008 06:00:00 3.66
0.3333 01-Jan-2008 07:00:00 3.83
0.375 01-Jan-2008 08:00:00 4.04
0.4167 01-Jan-2008 09:00:00 4.25
0.4583 01-Jan-2008 10:00:00 4.38
0.5 01-Jan-2008 11:00:00 4.37
0.5417 01-Jan-2008 12:00:00 4.27
0.5833 01-Jan-2008 13:00:00 4.12
0.625 01-Jan-2008 14:00:00 3.94
0.6667 01-Jan-2008 15:00:00 3.81
0.7083 01-Jan-2008 16:00:00 3.7
0.75 01-Jan-2008 17:00:00 3.69
>> tt = table2timetable(t,'RowTimes','Datetime')
tt =
18×2 timetable
Datetime Jday WL_m_
____________________ ______ _____
01-Jan-2008 00:00:00 0.0417 4.42
01-Jan-2008 01:00:00 0.0833 4.17
01-Jan-2008 02:00:00 0.125 3.95
01-Jan-2008 03:00:00 0.1667 3.76
01-Jan-2008 04:00:00 0.2083 3.61
01-Jan-2008 05:00:00 0.25 3.6
01-Jan-2008 06:00:00 0.2917 3.66
01-Jan-2008 07:00:00 0.3333 3.83
01-Jan-2008 08:00:00 0.375 4.04
01-Jan-2008 09:00:00 0.4167 4.25
01-Jan-2008 10:00:00 0.4583 4.38
01-Jan-2008 11:00:00 0.5 4.37
01-Jan-2008 12:00:00 0.5417 4.27
01-Jan-2008 13:00:00 0.5833 4.12
01-Jan-2008 14:00:00 0.625 3.94
01-Jan-2008 15:00:00 0.6667 3.81
01-Jan-2008 16:00:00 0.7083 3.7
01-Jan-2008 17:00:00 0.75 3.69
>> retime(tt,'monthly','mean')
ans =
1×2 timetable
Datetime Jday WL_m_
____________________ _______ ______
01-Jan-2008 00:00:00 0.39583 3.9761
>>