Data Handling Ron van Lammeren - Wageningen UR

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1 Data Handling Ron van Lammeren - Wageningen UR

2 Can I answer my scientific questions? Geo-data cycle Data handling / introduction classes of data handling data action models (ISAC) Queries (data exploration) attribute / thematic data query spatial / geometric data query raster data query 2/21

3 Data handling - classes.... new data set (A ) is based on handling (by class operators (Fq, Ft, Fa)) one or more old data sets (A1,.,An) A = F (A1,.,An)? Data handling classes: Fq Query Ft Transform Fa Alter / Process 3/21

4 Data handling - definition Query a data handling class of operators which doesn t change the thematic and geometric meaning of the original geo-data which doesn t change the (geo-)reference or data structure that only selects a subset out of the whole data set Transform a data handling class of operators which doesn t change the thematic and geometric meaning of the original geo-data that changes the (geo-)reference or data structure Alter/Process a data handling class of operators that changes the thematic and/or geometric meaning of the original geo-data which doesn t change the (geo-)reference and data structure 4/21

5 Data action model - introduction formal description of a methodology by diagrams and meta information using data handling classes (actions) implemented by geo-information tools (software) 5/21

6 Data action model notation and numbering 0A 0B Input LEGEND 1 2 vector 1A 2A Process raster query 3 transform 3A Output alter ISAC Diagram 6/21

7 Data action model exercise Question: What s the highest building for the land use type builded area? Data: buildings data set [raster data] land use data set [vector data] Exercise: Prepare a data action model For more information: practical manual 2006; Module 10 7/21

8 Geo-processing model ( D-A model in ArcGIS ) 8/21

9 Landscape analysis - Example 9/21

10 Why D-A models describe and explicate processes and the relationships between processes; make you able to update it dynamically whenever a change is made; let you edit the structure of the model by adding and deleting processes or changing the relationships between the processes; let you set values for the parameters of each data handling step of the model record changes, making the model output easily reproducible 10/21

11 Queries Thematic (attribute) data queries Structured Query Language (SQL) Boolean expression Boolean connector Geometric (spatial) data query By graphic By spatial relationship Intersect Containment Proximity Adjacency Raster data query 11/21

12 Attribute data queries: SQL > select > from > where an attribute out of the attribute list table(s) of a database condition or criterion for data query Obj_id Cover GWT Ca Abund. Lutum Object 1 grass grass maize maize water fruit grass housing grass maize grass water grass grass housing Data set: Ecol_Pot /21

13 Example SQL: formal definition of the selected green parcels? Object Cover GWT Ca Abund. Lutum Ojb_id 1 grass grass maize maize water fruit grass housing grass maize grass water grass grass housing Data set: Ecol_Pot Where is the Lutum value = 15? SELECT Object FROM Ecol_Pot WHERE Lutum = /21

14 SQL in ArcMap /21

15 Query expressions Boolean expression Simple query Lutum = 15 Logical operators =, <>, >, <, <=, >= Operands field, number, string Boolean connectors /operators AND, OR, NOT (NOR, XOR) Connect 2 or more expressions Complex query Used in the following operations A B Complement NOT Union OR Intersect AND s1 s2 s3 s4 C 15/21

16 Boolean connector definitions AND that produces a value of true if and only if both of its operands are true. OR that produces a value of false if and only if both of its operands are false. NOR that produces a value of true if and only if both of its operands are false. In other words, it produces a value of false if and only if at least one of its operands is true. NAND it produces a value of true if and only if at least one of its operands is false NOT that produces a value of true if its operand is false, and a value of false if its operand is true. XOR that produces a value of true if and only if one but not both of its operands is true. 16/21

17 Boolean applied A B C s1 s2 s3 s4 A AND B A OR B A NOR B A NAND B NOT A A XOR B s3 s2, s3, s4 s1 s1, s2, s4 s4, s1 s2, s4 17/21

18 Boolean example 18/21

19 Spatial data query by graphic (circle, box, polygon) by spatial relationship Containment Intersect Proximity Adjacency 19/21

20 Raster data query only by cell value operand refers to the raster itself use of boolean connectors / operators is possible multiple rasters Land use Soil /21

21 Summary: Geodata handling classes [ Query, Transform, Alter ] Data - action model [ Geoprocessing model ] Query: data handling operator which doesn t affect the thematic, geometric and (geo-)reference meaning of the original geo-data the result is an empty, full or sub set of the original data set the formal query is based on SQL or in words select (an attribute) from (table or database) where (the simple / complex condition is) the query type (thematic / geometric) depends on the condition Boolean algebra (complex condition) / =Truth tables / =Set theory Geometric queries are based on geometric and topologic conditions (containment (IN), intersect, proximity (NEAR), adjacency) 21/21

22 Study materials: Theory Chang, 2006, Chapter 11: Data Exploration Chapter 10 (11.2, 11.3, 11.4 only) (10.2, 10.3, 10.4 only) Practical: GRS practical manual, 2006/2009 Module 5: Queries Module 10: Data action models Wageningen UR

23 Exercise Map with information about commercial area per municipality in the Netherlands, as a result of a query. not known < 100 ha > 500 ha draw the original table perform the query in SQL language what s the query type? 23/21