Reader Dataset Parameter

Of course, perhaps the most important parameter is that which defines the dataset to be read. This too is found in the Navigator window:

As usual, double-clicking the parameter opens a dialog for it to be changed. You can change the dataset being read by selecting any other dataset - of the same format - within that dialog.

Multiple Dataset Selection

As long as the format is file-based (i.e. not a database) a Reader is capable of reading multiple source datasets:

To do this, when selecting the dataset to read simply select multiple files instead of a single one.

TIP

When selecting a source dataset, an advanced file browser is available. This allows you to select files from different folders, all at the same time!

File Dataset Types

When dealing with files it's useful to consider datasets as existing in two differnt forms: File-based and Folder-based

File-Based Datasets

A file-based dataset is just that: a single file that contains all layers of data. A format of this type has an internal structure that assigns data to different layers within the file.

Good examples of this are:

• AutoCAD DWG: Each DWG file is a dataset containing its own set of layers
• Microsoft Excel: Each Excel file is a dataset containing a set of sheets

In this scenario the dataset parameter is simply a pointer to the location of the file(s), here a single AutoCAD dataset:

Folder-Based Datasets

A folder-based dataset is still made up of files (of course). However, a format of this type DOES NOT have an internal way to define layers. Therefore each layer becomes a separate file within a folder.

Good examples of this are:

• Esri Shapefile: To store different layers requires multiple Shapefiles: e.g. roads.shp and railways.shp
• Comma-Separated (CSV): To store separate tables requires two separate CSV files

In this scenario the dataset parameter is a pointer to the individual files, here a set of layers in a shapefile dataset: