Import Tool

Import data from file

Description

The Import Tool lets you preview and import data from spreadsheet files, delimited text files, and fixed-width text files. In MATLAB^® Online™, you can also preview and import data from HDF5 files and netCDF files. You can interactively select the data to import and reuse the script or function that the tool generates to import other similar files.

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Open the Import Tool

• MATLAB Toolstrip: On the Home tab, in the Variable section, click Import Data.

• MATLAB command prompt: Enter uiimport(filename), where filename is a character vector specifying the name of a text or spreadsheet file (or, in MATLAB Online, an HDF5 or netCDF file).

Examples

Select Range to Import

Import ranges of data from a tab-delimited text file and replace nonnumeric values in the file.

Drag the cursor to select the cells to import. Press Ctrl to select noncontiguous ranges.

Modify the Variable Names Row field to indicate the row you want the Import Tool to use for the variable names.

By default, NaN replaces unimportable values in numeric cells. However, you can change this value to any other numeric value. Specify how to treat unimportable values on the Import tab, in the Unimportable Cells section.

Alternatively, exclude any row that contains an unimportable cell from being imported.

Click the Import Selection button . The new column vectors appear in your workspace.

Specify Decimal Separator and Date Format

Import dates and numbers from a text file into a table. Specify the decimal separator for numeric values in the file and a custom format for dates.

In the Imported Data section, select Table to import the file data into a table variable. In this example, the third column of data contains monetary amounts where the decimal separator is a comma. In the Delimiters section, select Delimiter Options. Then, under Decimal Separator, select , (comma).

The Import Tool appropriately converts the monetary values.

Specify that a column contains date or time data by changing the data type for the column to DATE/TIME. Click more date formats.... Scroll down the list to enter a custom date format.

Click the Import Selection button to import the table.

Related Examples

• Read Text File Data Using Import Tool
• Read Spreadsheet Data Using Import Tool
• Supported File Formats for Import and Export

Programmatic Use

uiimport

uiimport opens a dialog to interactively load data from a file or the clipboard. MATLAB displays a preview of the data in the file.

uiimport(filename)

uiimport(filename) opens the file specified in filename using either Import Tool or Import Wizard depending on the file type. For spreadsheet and text files (and, in MATLAB Online, netCDF files), uiimport opens the file using Import Tool. For all other file types, such as image, audio, or MAT-files, uiimport opens the file using Import Wizard.

uiimport('-file')

uiimport('-file') presents the file selection dialog first.

uiimport('-pastespecial')

uiimport('-pastespecial') presents the clipboard contents first.

S = uiimport(___)

S = uiimport(___) opens the file using Import Wizard and stores the resulting variables as fields in the struct S.

Limitations

• The Import Tool does not support importing data from HDF5 files that use the Family driver, the Multi driver, or the Split driver. To import data from a file that uses one of these three drivers, use either the MATLAB high-level HDF5 functions (for example, h5read or h5readatt) or the MATLAB low-level HDF5 functions.

Version History

R2024a: Import HDF5 data in MATLAB Online

You can import HDF5 data in MATLAB Online. Using this tool, you can:

• Visualize the structure and contents of HDF5 data interactively.

• Search for specific groups, datasets, and attributes.

• Graphically select and deselect groups, datasets, and attributes to import.

• Generate reusable MATLAB code to import HDF5 data.

R2023b: Import netCDF data in MATLAB Online

You can import netCDF data in MATLAB Online. Using this tool, you can:

• Visualize the structure and contents of netCDF data interactively.

• Search for specific variables and attributes.

• Graphically select and deselect variables and attributes to import.

• Generate reusable MATLAB code to import netCDF data.

R2020a: Importing HDF4 files using the Import Tool is no longer supported

Import Tool no longer supports importing HDF4 files. To programmatically import HDF4 or HDF-EOS files, use the hdfread function instead.