Fall 2010 | 11.520/11.188 Recitation 4—Class Review | Nov 10, 12, 2010 Prepared by Lulu Xue and Shan Jiang | Q&A: [email protected] Page 1 of 2 TOPICS KEY POINTS LECTURE/LAB Thematic Mapping Data classification method Quantile\equal interval\natural break Lab 1; Lab 2; Exclusion Exclusion (visual representation; what should be excluded) ; Definition query (calculation; what should be included); Remember to annotate the excluded features in your legend. Lab 4; Projection system Local projected system, lat\lon system; how to convert projection system from one to another; how to assign a projection system to a layer. Lab 2 Part III; Lab 3 Part IV; Lect. Oct 6 GIS Models; Querying (attribute table or feature); Data Manipulation Vector v.s. Raster; attribute tables Lect. Sept 15; Select by attribute How to query a table to select the records of interest? (e.g., how to find out the minimum/maximum/mean value of a data column? --Sort ascending/descending, or check “Statistics”) If you have features selected, any of your subsequent operations are applied only to the selected features. Lab 3; HW 1 Part 2 Select by location Field calculator When dividing a value using “Field Calculator”, zero-value records should be excluded first—you can use definition query to preclude the zero-value records, or you can “select by attribute” to only select non-zero-valued records as denominators. Lab 3 Part II; Join table to a layer Join attributes from a table Keep all records| Keep only matching records Lab 5; Lect. Sept 22; HW 3 Part 1 Aggregation Summarize in ArcGIS; (Database manipulation in Ms-Access) HW 1 Part 2; HW 2 Part 1; Lect. Sept 22; Recitation 2 Census Data Census Geography; Summary Levels; Summary Files (SF1 & SF3) Lect. Sept. 29; Lab 5; HW 1 Part 1; HW 2 Part 1Fall 2010 | 11.520/11.188 Recitation 4—Class Review | Nov 10, 12, 2010 Prepared by Lulu Xue and Shan Jiang | Q&A: [email protected] Page 2 of 2 Spatial Analysis: Vector Models Buffer Dissolve: to remove buffer feature overlap Not all cases need to dissolve the resulting buffers. In some cases, individual buffer for each feature would be more reasonable. Lab 3 Part III; Lab 6; Lect. Oct. 13; Recitation 3; HW 1 Part 2; HW 2 Part 2 Union v.s. Intersect Erase Spatial join* Creates a table join where fields from one layer's attribute table are appended to another layer's attribute table based on the relative locations of the features in the two layers. Spatial Analysis: Raster Models Raster analysis Convert: features to raster; How to set up raster properties (cell size, mask area, extent) Lect. Oct. 20; Lab 7; Recitation 3; HW 3 Part 1; Lect. Nov. 10 Neighborhood statistics v.s. zonal statistics Spatial analyst tools Not limited to the ones mentioned in the lab exercises or homework. In cases where you need other functions, you may refer to the ArcGIS (online) help for in-depth guidance. *Spatial join also has summarizing function (see examples in ArcGIS Desktop HelpIndexspatial joins/aggregating fields) If more than one join feature is found for a target feature, and you want to maintain the exact same number of output features as Target features (input features) you need to set a Join merge rule. The Join merge rule combines values from a single field for multiple rows in the join feature class when more than one join feature is found for a target feature. For example, a city land use feature class has a text field called LU containing two letter characters indicating each polygon's land use classification (such as 'CO' for commercial). The land use feature class is then joined to a city district polygon feature class, where the districts are the target of the spatial join. The one-to-one join operation is chosen so the new feature class will have the same number of features as the original input districts, but it will have the attributes of the land use feature class. The Join merge rule was applied to the LU classification field (with a comma as the