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readall

Read all data in datastore

Syntax

data = readall(ds)

Description

example

data = readall(ds) returns all the data in the datastore specified by ds.

If all the data in the datastore does not fit in memory, then readall returns an error.

Examples

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Create a datastore from the sample file airlinesmall.csv, which contains tabular data.

ds = tabularTextDatastore('airlinesmall.csv','TreatAsMissing','NA');

Modify the SelectedVariableNames property to specify the variables of interest.

ds.SelectedVariableNames = {'DepTime','ArrTime','ActualElapsedTime'};

Read all the data in the datastore.

T = readall(ds);

readall returns all the data in a table.

View information about the table.

T.Properties
ans = struct with fields:
             Description: ''
                UserData: []
          DimensionNames: {'Row'  'Variables'}
           VariableNames: {'DepTime'  'ArrTime'  'ActualElapsedTime'}
    VariableDescriptions: {}
           VariableUnits: {}
      VariableContinuity: []
                RowNames: {}

View a summary of the output table.

summary(T)
Variables:

    DepTime: 123523x1 double

        Values:

            Min            1       
            Median         1335    
            Max            2505    
            NumMissing     2351    

    ArrTime: 123523x1 double

        Values:

            Min            1       
            Median         1522    
            Max            2608    
            NumMissing     2656    

    ActualElapsedTime: 123523x1 double

        Values:

            Min            11                
            Median         102               
            Max            1650              
            NumMissing     2657              

Create a datastore from the sample file, mapredout.mat, which is the output file of the mapreduce function.

ds = datastore('mapredout.mat');

Read all the data in the datastore.

T = readall(ds);

View a summary of the output table.

summary(T)
Variables:

    Key: 29x1 cell array of character vectors

    Value: 29x1 cell

Input Arguments

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Input datastore. You can use the datastore function to create a datastore object from your data.

Output Arguments

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All data in the datastore, returned as a table or cell array.

  • For TabularTextDatastore and SpreadsheetDatastore objects, data is a table with variables corresponding to the SelectedVariableNames property.

  • For ImageDatastore objects, data is a cell array where each element displays the size and data type of the corresponding image data. For example, [480x640x3 uint8] describes the size of uint8 data corresponding to a color image.

  • For KeyValueDatastore objects, data is a table whose variable names are Key and Value.

  • For FileDatastore objects, data is a cell array containing the data returned by the read function that is specified by the 'ReadFcn' parameter value in the fileDatastore function.

After the readall function returns all the data, it resets ds to point to the beginning of the datastore for these objects: SpreadsheetDatastore, KeyValueDatastore, TallDatastore, and TabularTextDatastore.

See Also

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Introduced in R2014b

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