SOC 4650/5650 - Lecture-B - Spatial Joins

Remote version of the Spatial Joins lecture for the Spring 2020 semester

Transcript

1. SPATIAL JOINS INTRO TO GISC CHRISTOPHER PRENER, PH.D. SPRING 2020 (REMOTE) LECTURE B
2. AGENDA INTRO TO GISC / LECTURE B 1. Front Matter 2. Spatial Joins 3. Select by Location 4. Back Matter
3. 1 FRONT 
 MATTER
4. Lab-B is due in two weeks. Final project draft materials are due in two weeks! 1. FRONT MATTER ANNOUNCEMENTS We do not have a class meeting next week - please take the time to go through your final project materials.
5. SPATIAL JOINS 2
6. KEY TERM The spatial joins 
 operation is used to apply 
 identifiers from a higher order polygon to data or to aggregate data to that higher order polygon.
7. SPATIAL JOINS - IDENTIFY Target Layer ID Shape 104 Point 105 Point 106 Point 107 Point 108 Point 109 Point 110 Point 111 Point 112 Point 113 Point 114 Point 23 ID Shape 23 Polygon Source Layer
8. SPATIAL JOINS - IDENTIFY Target Layer ID Shape Tract 104 Point 23 105 Point 23 106 Point NA 107 Point NA 108 Point 23 109 Point 23 110 Point 23 111 Point 23 112 Point NA 113 Point NA 114 Point NA 23 ID Shape 23 Polygon Source Layer
9. SPATIAL JOINS - AGGREGATE Source Layer ID Shape 104 Point 105 Point 106 Point 107 Point 108 Point 109 Point 110 Point 111 Point 112 Point 113 Point 114 Point 23 ID Shape 23 Polygon Target Layer
10. SPATIAL JOINS - AGGREGATE Source Layer ID Shape 104 Point 105 Point 106 Point 107 Point 108 Point 109 Point 110 Point 111 Point 112 Point 113 Point 114 Point 23 ID Shape Count 23 Polygon 6 Target Layer
11. EXAMPLE We have point data for 
 homicides in the City of
 St. Louis. We also have a data 
 set of census tracts. A spatial join can tell us (a) which tract each murder occurred in and (b) how many murders occurred in each tract.
12. SELECT BY LOCATION 3
13. KEY TERM The select by location 
 operation is used to subset 
 geometric data based on spatial relationships. It works like the filter() function from dplyr, but based on space instead of attributes.
14. SBL WITH POINTS (CONCEPTUAL) Target Layer ID Shape 104 Point 105 Point 106 Point 107 Point 108 Point 109 Point 110 Point 111 Point 112 Point 113 Point 114 Point
15. SBL WITH POINTS (CONCEPTUAL) Target Layer ID Shape 104 Point 105 Point 106 Point 107 Point 108 Point 109 Point 110 Point 111 Point 112 Point 113 Point 114 Point 23 ID Shape 23 Polygon Source Layer
16. SBL WITH POINTS (CONCEPTUAL) Target Layer ID Shape 104 Point 105 Point 106 Point 107 Point 108 Point 109 Point 110 Point 111 Point 112 Point 113 Point 114 Point ID Shape 23 Polygon Source Layer 23
17. EXAMPLE We have point data for 
 homicides in the City of
 St. Louis. We also have a data 
 set of census tracts for north city. A select by location operation can subset all of the murders that occur in the north city tracts.
18. 4 BACK 
 MATTER
19. AGENDA REVIEW 4. BACK MATTER 2. Spatial Joins 3. Select by Location
20. REMINDERS 4. BACK MATTER Lab-B is due in two weeks. Final project draft materials are due in two weeks! We do not have a class meeting next week - please take the time to go through your final project materials.