This dialog is activated by selecting the Import -> Import ASCII... command from the File Menu. It can be used to select several files at a time. The files are imported using a set of default options. You can display and edit these options by pressing the Advanced button. All your changes to the default import parameters will be saved.
You can define a custom file filter in the Files of type: field in order to preselect files. For example, typing *.mydata and then the "Enter" key will set a filter that will show only files of the form "XXX.mydata" in the directory view.
Concerning the character which is used to separate column values, you must bear in mind that there is no grouping of separators, so if you use "SPACE", you must use only one separator between each column or check the Simplify white spaces option.
If your data files have a particular structure, for example if they begin with several lines describing your experiment, you may skip the first n lines of the file. You can also skip all lines starting with a comment character/string. The comment string can be customized using the Ignore lines starting with text edit box.
If you choose to use the first line to define column names and/or the second line as comments to be displayed in the table header, you must use the same separator between column names as that used between data columns.
If the files you want to import were created using a different convention for the decimal and thousands separator characters than the current setting, then the Decimal Separators option can be used to configure QtiPlot to use a matching convention. For example, when a comma character is used for the decimal point instead of the dot character, simply change the Decimal Separators option to match. You can have QtiPlot ignore the Thousands separator altogether with the Omit thousands separator option.
Finally, you can specify the kind of data to be imported in each column by pressing the Column Types... button or by clicking on the column header in the preview table. A dialog will pop-up allowing you to choose a data type (the default data type for each column is Numeric) and a column format date/time columns.