Version History of Land Areas Polygon Layer (20Y) in Sweden Map Data Collection
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The 'land20y__history' table is a detailed record of historical geographical data, sourced from the 'Lantmäteriet' website in Sweden. Being a history table, it maintains a version history of its base table rows, tracking changes over time. Each row in the table represents a unique version of a geographical feature, identified uniquely by a combination of the row number and the date extracted from the data source. The data includes the start and end dates for each version, with a null end date signifying the most current version. The table features rich geographic data in the form of text, JSON and geometric formats derived from shapefile data. This includes information on the type of geographic features (such as polygons), their textual and JSON representations, their centroid points, and their center coordinates (X and Y). The table is particularly useful for tracking changes in land areas over time, as indicated by the 'KKOD' values. With this data, analysts could track changes in land use patterns, monitor ecological changes, or support infrastructure planning by providing historical context. Furthermore, due to its detailed geographic information, it can be utilized in creating comprehensive maps or in geographic information system (GIS) applications to study historical geographical changes.
Field Descriptions
| Name |
Data type |
Description |
| _start_date | date | This column stores the date when a specific row was extracted from the data source. It is a part of the combination that uniquely identifies each row in this version history table. |
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| _end_date | date | This column contains the date when a new version of a specific row was extracted from the data source. If the value is null, it indicates that the row is the most recent version. |
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| _row_number | long | This column contains the row number of the raw data from the data source. This, in combination with the '_start_date' column, uniquely identifies each row in the version history table. |
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| KKOD | string | This column contains the category code. In the context of the dataset, this could relate to different categories of land types or geographic features. |
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| geom_geojson | string | This column contains the geographical data in GeoJSON format. This can include data about land areas or other geographic features. |
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| geom_geotext | string | This column contains the geographical data in text format. This is another representation of the geographic features, similar to the 'geom_geojson' column. |
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| geom_type | string | This column defines the type of geometric shape that represents the geographical feature. For example, it could be a polygon representing a land area. |
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| geom_centroid | string | This column contains the centroid point of the geographical shape in the 'geom_geojson' and 'geom_geotext' columns. The centroid is the geometric center of a two-dimensional shape. |
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| geom_center_x | double | This column contains the X-coordinate of the centroid of the geographical feature. It is a part of the geographic data that describes the position of the feature. |
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| geom_center_y | double | This column contains the Y-coordinate of the centroid of the geographical feature. It is another part of the geographic data that describes the position of the feature. |
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