Data Analysis

When a new data file is loaded into MapLink Pro Studio, two stages of processing are involved:

• Analysis, when the data file is scanned to extract the spatial extent of the data in the file, and a list of all the feature classes contained in the data together with relevant information such as feature codes, labels, and statistics. Once data analysis has been performed, even if the data has not been fully processed, details of the extent and composition of the data have therefore been loaded.
• Processing, when the data is extracted from the data file, taking into account any spatial or feature-base filtering constraints that have been specified by the user via feature masking and input clipping respectively. At this stage the processing defined for the layer as a whole is also applied.

To view the results of Data Analysis

• Select the data file in the Project Tree.
• Select Data | Data Extent or click the Data Properties button in the sidebar, to access the Data File Property Sheet.
• The Data Extent tab shows the physical extent of the data in the coordinate system units used in the input data file.
• Click on the Vector Properties tab to see a full list of all the separate feature classes found in the data file. For each feature class the following information is provided:
• Feature Code. The Feature Code is usually a property of the input dataset format, although in some cases MapLink Pro will construct synthetic feature codes.
• Label. The label is usually a property of the input dataset format, although in some cases MapLink Pro will construct synthetic labels.
• Rings. The number of separate rings identified in the data file that relate to entities of the given feature code. The number of rings can often be taken as an indication of the number of separate polygons in the source data, although the use of multiple rings per polygon is common in GIS datasets. Geometrically, a polygon consists of one outer ring and zero or more inner rings, which are rendered as holes within the polygon.
• Lines. The number of separate polylines identified in the data file that relate to entities of the given feature code.
• Points. The number of separate point entities identified in the data file that relate to entities of the given feature code.
• Text. The number of separate text entities created from the data file that relate to entities of the given feature code. Text features can arise in three different ways:
• In some datasets, text features exist explicitly in the data. Land-Line Plus is a well-known example of this.
• In some datasets, MapLink Pro creates text entities by analysing textual attribute data held with the geometrical features in the input data, taking advantage of the dataset specification to give meaning to the attributes. In such cases the text entity creation is either automatic or (as in the case of VMAP0 data) controlled by a MapLink Pro configuration file.
• In other datasets (notably the MIF and Shapefile configurable datasets) you have control over the attributes that are used to create the text entities.
• Coords. The number of separate coordinates identified in the data file that relate to entities of the given feature code.
• Chars. The number of separate characters identified in the data file that are part of the text entities of the given feature code.

The results of data analysis are stored in a MapLink Pro Studio Catalogue file (with the same name as the corresponding MapLink Pro Studio Project file, but with an extension .mlc) that is saved into the Project file directory. When the project is subsequently worked on, the information is read directly from the Catalogue file, thus avoiding the need to analyse the input data files again. Occasionally, however, you may need to re-catalogue the file.