1 Peter Fox GIS for Science ERTH 4750 (98271) Week 10, Friday, April 6, 2012 Lab:

First: from Tuesday 2

More thematic maps Bar charts to show the quarterly rainfall for the New England States. But … because some states have multiple measurement sites we have to group them. Query to get a new table just for each state Create Thematic map, select Bar Chart > Next > select columns to plot > Next > OK. 3

Creating points for intersections of lines Open the street file nyrensd. Make 2 copies of the nyrensd file and give each a unique name (File > Save copy as) such as str1 and str2. Open the 2 new files you have created. Choose Query > SQL select and enter: Select columns = str1.streetname + "&&" + str2.streetname from Tables = str1, str2 where condition = str1.obj Intersects str2.obj and str1.streetname <> str2.streetname into Table Named = Intersection Save it 4

Adding/ comparing Past exercise: make a spreadsheet of the zip codes for 10 of your friends in the US. Read them in to MapInfo, geocode them using zip codes and us_zips, and plot them on a map of the US (usa). Using this table of friends zipcodes, add their ages and add 5 new friends (or class members) to the table. Plot them on a map that distinguishes new friends from old and their ages. 5

Creating attributes Make CL editable > put objects on map with tools > Map > Save CL objects (these are in your tool bar) and name the new table Open new Browser window Table > Maintenance > Table structure > add fields (add "area" column) Table > Update column > Column = "area" > Value > Assist > Function > Area Save table 6

Map Basic Programs is the MapBasic program.mbx is the compiled program 7

Options – Show Mapbasic Window open table "c:\mapinfo\data\world.tab" interactive map from world select * from world where pop_1994> into selection browse * from selection map from selection Using MapBasic Plot variograms… in preparation for kriging (next week) 8

Statistics (originally from bles/county/rensselaer.htm ) bles/county/rensselaer.htm Geocode the table by place names using Rens2000 and common sense. [You might add the lon/lat to your table…] 9

Statistics The uncertainty in a value estimated by weighted averages is one over the square root of the sum of the weights. –Use IDW to estimate the uncertainties in estimated values at (73.58W, 42.69N), at (73.45W, 42.83N), and at (73.46W, 42.51N) –Hint: MapBasic is simplest, or use MapInfo to get distances, then Excel for the calculations. 10

Mapping aspects of radon3 –Make a thematic map of the 'Living' points using different colored symbols to represent the value ranges. –Make a thematic map using regions instead of points. Which is a better representation of the data? –Make a thematic map of the 'Basement' points using regions. How does the pattern compare (visually, for now) to the 'Living' observations? Hint: make your thematic maps with color schemes that will allow best visual comparison. 11

Mapping aspects of radon3 Make a surface plot by grid interpolation (Inverse distance weighting) of the geocoded points while removing Schaghticoke from the data set. Include the points on the map (use a similar coloring scheme for this) See how well the interpolation routine (IDW) predicts the value at Schaghticoke. 12

E.g. for a project on this Repeat the procedure 4 more times using different values for the exponent and search radius. –Which value of the exponent gives the best match to the Schaghticoke value? –How many of them match the value within its uncertainty? –Make a layout window that contains your 4 trial maps (label the maps). Discuss the relative usefulness/accuracy of the various representations of the data. Which would you use to make a presentation to the County Senate? Why? 13

Others to make sure you complete 14

Back to Excel 15

Example We see that the calculations match the results of the Excel trend-line function. Regression with equal weighting of all data implied. 16

Adjusted e.g. The final data point has little influence on the solution when its uncertainty is increased by a factor of 3. Weighting (equal) also influences the standard errors in the estimated unknowns. 17

Unequal weighting 18

Tue: Lon/lat from geocoded table? You may want to see the latitude and longitude in your geocoded table. There are 2 ways to do this depending on whether you want a new table or want to put the lat/lon in your original table. To create a new table use Query > SQL select. Under select columns, enter columns you want in the new table and then also put: –CentroidX(obj) "Longitude", CentroidY(obj) "Latitude" 19

And To add the lat/lon to an existing table, select Table > Maintenance > Table structure and add 2 new columns to your table. Call the Lat and Lon and make them ‘float’ types. Then choose Table > Update column. Enter your table name under Table to update and Get value from Table. Column to update should be your lat or lon and Value shoud be CentroidY(obj) for latitude and CentroidX(obj) for longitude. 20