{"id":12443,"date":"2021-07-11T21:00:22","date_gmt":"2021-07-12T01:00:22","guid":{"rendered":"https:\/\/blogs.mathworks.com\/pick\/?p=12443"},"modified":"2021-07-14T09:06:04","modified_gmt":"2021-07-14T13:06:04","slug":"import-explorer-to-help-you-with-importing-table-data","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/pick\/2021\/07\/11\/import-explorer-to-help-you-with-importing-table-data\/","title":{"rendered":"Import Explorer to help you with importing table data"},"content":{"rendered":"
Jiro<\/span><\/a>'s Pick this week is <\/span>Import Explorer for tables<\/span><\/a> by <\/span>Jan Studnicka<\/span><\/a>.<\/span><\/div>
When importing data as a table, you can use <\/span>detectImportOptions<\/span><\/a> to customize how you bring in your data. You can choose to import specific columns, specify the data type of each column, specify how to treat missing values, and many more. <\/span><\/div>

Import Explorer<\/span><\/h3>
Jan's entry is a visual tool to help with this customization. It also lets you save the output for <\/span>detectImportOptions<\/span> so that you can programmatically reproduce the operation. See this in action.<\/span><\/div>
\"import_explorer.gif\"<\/img><\/div>

Programmatic Approach<\/span><\/h3>
As a comparision, here's how you would do it programmatically from scratch.<\/span><\/div>
opts = detectImportOptions(<\/span>\"airlinesmall.csv\"<\/span>)<\/span><\/span><\/div>
opts = <\/span><\/div>
DelimitedTextImportOptions with properties:\r\n Format Properties:\r\n Delimiter: {','}\r\n Whitespace: '\\b\\t '\r\n LineEnding: {'\\n' '\\r' '\\r\\n'}\r\n CommentStyle: {}\r\n ConsecutiveDelimitersRule: 'split'\r\n LeadingDelimitersRule: 'keep'\r\n TrailingDelimitersRule: 'ignore'\r\n EmptyLineRule: 'skip'\r\n Encoding: 'Shift_JIS'\r\n Replacement Properties:\r\n MissingRule: 'fill'\r\n ImportErrorRule: 'fill'\r\n ExtraColumnsRule: 'addvars'\r\n Variable Import Properties: Set types by name using setvartype\r\n VariableNames: {'Year', 'Month', 'DayofMonth' ... and 26 more}\r\n VariableTypes: {'double', 'double', 'double' ... and 26 more}\r\n SelectedVariableNames: {'Year', 'Month', 'DayofMonth' ... and 26 more}\r\n VariableOptions: Show all 29 VariableOptions \r\n\tAccess VariableOptions sub-properties using setvaropts\/getvaropts\r\n VariableNamingRule: 'modify'\r\n Location Properties:\r\n DataLines: [2 Inf]\r\n VariableNamesLine: 1\r\n RowNamesColumn: 0\r\n VariableUnitsLine: 0\r\n VariableDescriptionsLine: 0 \r\n\tTo display a preview of the table, use preview<\/div><\/div><\/div><\/div><\/div>
opts.VariableTypes([9 17 18]) = {<\/span>'categorical'<\/span>};<\/span><\/span><\/div><\/div>
opts.SelectedVariableNames = opts.VariableNames([1 2 3 5 7 9 10 15 16 17 18]);<\/span><\/span><\/div><\/div>
data = readtable(<\/span>\"airlinesmall.csv\"<\/span>,opts);<\/span><\/span><\/div><\/div><\/div>

Import Tool<\/span><\/h3>
Of course, there is the <\/span>Import Tool<\/span><\/a> that comes with MATLAB. You can do many of these customizations from the tool.<\/span><\/div>
\"import_tool.png\"<\/img><\/div>
Jan's Import Explorer gives you a bit more options, since <\/span>detectImportOptions<\/span> provides those. In addition, Jan's tool works with multiple files, in which case it uses the <\/span>datastore<\/span><\/a> function under the hood.<\/span><\/div>
A small request I have is for this to work with other file types, such as Excel files. Currently, this tool only works with CSV and TXT files.<\/span><\/div>

Comments<\/span><\/h3>
Give this a try and let us know what you think<\/span> <\/span>here<\/span><\/a> <\/span>or leave a<\/span> <\/span>comment<\/span><\/a> <\/span>for Jan.<\/span><\/div>\r\n<\/div>