Matlab equivalent of Python Panda's dtypes

Question

If I have a pandas.DataFrame in python I can inspect the data types for the DataFrame with the dtypes attribute. How can I do the same with a Matlab table? I poked around the Properties mechanism but didn't find anything type oriented there.

Isn't there a Property called VariableTypes? mathworks.com/help/matlab/ref/table.html — rahlf23
– rahlf23, Commented Oct 1, 2018 at 20:12
If I try a . tab completion after Properties I get presented with Description, DimensionNames, RowNames, UserData, VariableContinuity, VariableDescriptions, VariableNames, and VariableUnits. I'm in Matlab 2018a. Upon reading the doc it seems VariableTypes is an input string to coerce a data type. — jxramos
– jxramos, Commented Oct 1, 2018 at 20:16
Looks like there's also a vartype function which grabs variables from a table of a certain type. But that's a different operation too. I'm trying to do something more introspective than something selective. — jxramos
– jxramos, Commented Oct 1, 2018 at 20:22

jxramos · Accepted Answer · 2018-10-01 20:49:13Z

3

It appears that you can call the following:

varfun(@class,t,'OutputFormat',table)


class_var1   class_var2    class_var3    class_var4 
__________   __________    __________    __________

double       double        double        double

where t is your table. I am referencing the answer here.

Further documentation on varfun is available here as well.

edited Oct 1, 2018 at 20:49

jxramos

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answered Oct 1, 2018 at 20:24

rahlf23

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2 Comments

jxramos Over a year ago

Nice find, its choking on my particular table, but I think because it has some nested matrix type or something. When I inspect it in the DataInspector there are some "merged" columns for some of the variables, eg variable 2 spans 4 columns: class(t) ; ans = 'table'; varfun(@class,t,'OutputFormat',cell) ; Error using cell Not enough input arguments.

Cris Luengo Over a year ago

@jxramos: If you want to find the class for an individual column, you can also simply say class(t.var1).

jxramos · Accepted Answer · 2018-10-01 20:32:08Z

0

Looks like one way to get this information (while unfortunately getting a bunch of other things) is with a simple call to summary.

Here's some sample output

K>> summary(t)

Variables:

    var1: 2966185×1 double

        Units:  sec
        Values:

            Min       56.207
            Median    7466.7
            Max        14878

    var2: 2966185×4 double

        Values:
                        var2_1        var2_2      var2_3      var2_4
                      ________    __________    ________    ________

            Min       -0.99966      -0.99901    -0.99887    -0.99998
            Median     0.01644    -0.0044018     0.12838      0.1564
            Max        0.98176       0.96433     0.99998           1

    var3: 2966185×3 double

        Units:  g
        Values:
                         var3_1        var3_2        var3_3
                      __________    _________    __________

            Min           -2.779      -3.1366       -3.6089
            Median    -0.0002124    -0.002221    -0.0020435
            Max           3.7874       5.9634        2.8443


    var4: 2966185×1 double

        Values:

            Min          0
            Median       5
            Max          5

answered Oct 1, 2018 at 20:32

jxramos

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2 Comments

rahlf23 Over a year ago

Is this telling the data type though?

jxramos Over a year ago

@rahlf23, sure, eg var1: 2966185×1 double, it's a double column vector, and var 2 and 3 are matrices of double. That appears to be what broke the varfun solution which probably handles single dimension variables.

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