How to sum up over dates?

I have table with T

date location sales
--------------------
1/1 NY 100
1/2 NY 105
1/1 LA  70
1/2 LA 90

I want to sum up over dates to create T1 with

1/1 170
1/2 195

What is the next step?

[alpedhuez]

https://www.mathworks.com/matlabcentral/answers/406864-how-do-i-sum-over-one-dimension-of-a-multidimensional-array

Answer 1

[Cris LaPierre]

Convert your dates to datetimes and use groupsummary with the groupbins input set to 'day' and your method set to 'sum', and datavars specified as your sales variable. Use the following syntax.

G = groupsummary(T,groupvars,groupbins,method,datavars)

[alpedhuez]

what for groupvars?

[Cris LaPierre]

What do you want to group by?

[alpedhuez]

So is it

groupsummary(T,'date','day','sum','sales');

?

[Cris LaPierre]

Looks good to me, but you have the data, so why not run it and see if you get the result you want?

[alpedhuez]

Now suppose I have two variables

date location sales visitors
--------------------
1/1 NY 100 3
1/2 NY 105 5
1/1 LA  70 6
1/2 LA 90 10

I want to sum sales and visitors for each date:

date sales visitors
--------------------
1/1 170 9
1/2 195 15

Does it

groupsummary(T,'date','day','sum',{'sales','visitors'});

?

[Cris LaPierre]

What happens when you run that line of code?

[alpedhuez]

Yes it works fine. Now is it possible to "sum" for a variable and "mean" for another variable?

[Cris LaPierre]

Yes. To take the sum and mean of sales and visitors, I'd do this

groupsummary(T,'date','day',{'sum','mean'},{'sales','visitors'});

[alpedhuez]

But then how it goes with the sum for two variable and mean for one vaiable?

[Cris LaPierre]

I misspoke earlier. All methods are applied to all datavars. With groupsummary, it is not possible to separate the stats by variable. To do that, i would probably compute the all stats for all variables, then remove the columns I do not want.

[alpedhuez]

No I mean, suppose I now have three variables sales, visitors, profits and want to take sum of sales and visitors and mean of profits. Is it

groupsummary(T,'date','day',{'sum','sum','mean'},{'sales','visitors','profits'});

?

[alpedhuez]

What will be pseudo code?

[Cris LaPierre]

See my previous reply. All methods are applied to all datavars.

All your answers can be found by going through the documentation for groupsummary.