Dayname for year using groupsummary

i have table for 1 full year.

i need to regroup table into dayname for each month.

if i use

groupsummary(MyTable, 'Date_Time', 'dayname', @nanmean);

am getting 7 days averaged for 1 year but i need it for indvidual months like each month days are averaged.

final output should be 7 rows 12 colums.

7 represnts dayname 12 represents each month.

Answer 1

[TARUN]

Hi @Ajay Nair,

The reason you are getting just 7 rows is because

groupsummary(MyTable, 'Date_Time', 'dayname', @nanmean);

averages across the entire year.

To get weekday averages for each month (a 7×12 matrix), you’ll need to group by both day name and month.

You can use the following workaround to fix it:

MyTable.Month = month(MyTable.Date_Time);
MyTable.DayName = categorical(day(MyTable.Date_Time, 'longname'));
Summary = groupsummary(MyTable, {'DayName', 'Month'}, 'nanmean');
Result = unstack(Summary, 'nanmean_YourVar', 'Month');

‘YourVar’ is the variable that you are using for averaging.

This gives you 7 rows (Mon–Sun) and 12 columns (Jan–Dec), just as needed.

Please refer to this documentation for more details:

GroupSummary: https://www.mathworks.com/help/matlab/ref/double.groupsummary.html