grpstats for several variables

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Ongun Palaoglu 2019-9-8

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https://ww2.mathworks.cn/matlabcentral/answers/479448-grpstats-for-several-variables

评论： Ongun Palaoglu 2019-9-12

Hello everybody,

i have values for Sodium, creatinine and many more variables for patients. I need to calculate mean median values of them. Should i use everytime mean(ds.Sodium) or is there a easier way to do that ? i ve been trying to use grpstats function i couldnt make it work. if someone would explain me i would be very happy. thank you

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Adam Danz 2019-9-8

What problems are you having? There are lots of examples in documentation which is the first place to go for help.

https://www.mathworks.com/help/stats/grpstats.html

Adam Danz 2019-9-9

Ongun Palaoglu's answer moved here as a comment.

True,

DSSTATS = grpstats(DS,GROUPVARS,WHICHSTATS) .

stat1 = grpstats(ds, {'Sodyum' , 'AST'} , {'mean' , 'median'}) i did this, for my dataset ds, {variables} , {what i want to calculate'means'}

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Answer 1

Adam Danz 2019-9-9

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编辑：Adam Danz 2019-9-9

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Have a look at the list of statistics that are accepted as character vectors. Note that 'median' is not one of the options.

https://www.mathworks.com/help/stats/grpstats.html#bthgdq6-whichstats

Instead, you'll need to use a function handle to list 'median' as a stat.

stat1 = grpstats(ds, {'Sodyum', 'AST'} , {'mean', @median});

That fixes any syntax issues. If problesm persist, please describe the problem in detail and share the result of the following line (assuming ds is a table which appears to be the case).

head(ds) % if ds is a table

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Adam Danz 2019-9-9

编辑：Adam Danz 2019-9-11

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@ Ongun Palaoglu, please use the comments section for discussion rather than posting comments as answer.

I looked at your data and it will be very easy to follow the advice I provided above.

Frist convert your dataset to a table.

T = dataset2table(ds1);

Because your table contains columns that are non-numeric, you need to specify which columns should be used for the statistics. To do that, use the DataVars property in grpstats(). I listed "AST" and "ALT" but you can replace that with whatever numeric columns you'd like to use for the statistics.

 stat1 = grpstats(t, {'Sodyum', 'AST'} , {'mean', @median},'DataVars',{'AST','ALT'})
 %  -->                                               here  ^^^^^^^^^^^^^^^^^^^^^^

About recommending a book, I actually don't recommend a book. Whenever you use a new function, look up that function in the documentation and read about it's inputs, outputs, and what the function does. Also look at it's optional parameters. This is the best way to learn how to use functions.

Adam Danz 2019-9-11

在 MATLAB Online 中打开

Ongun, please spend some time reading through the documentation. I provided a link to the grpstats() function. Often times it help looking at the examples too. Look for an example in the grpstats page that matches your inputs.

In this line

stat1 = grpstats(T, {'Sodyum', 'AST'} , {'mean', @median},'DataVars',{'ALT'})

you are computing the mean and median ALT for each "Sodym" and "AST" group -combination. Those group combinations are the row names in the table output.

Ongun Palaoglu 2019-9-12