geography - plotting a {{Latitude,Longitude}} list on top of a GIS shapefile

I have a dataset composed of points specified in {Latitude,Longitude} format. Call it latlong for the purposes of this question. It displays properly with

Graphics[{Point /@ 
   Map[GeoGridPosition[GeoPosition[#], 
       "Mercator"][[1]] &, {latlong}, {2}]}]

I also have a shape file that contains the boundaries of the counties in which the latlong points reside. If I query Import[demo.shp", "CoordinateSystemInformation"], I get

"GEOGCS" -> {"GCS_North_American_1983", 
  "DATUM" -> {"North_American_Datum_1983", 
    "SPHEROID" -> {"GRS_1980", 6.37814*10^6, 298.257}}, 
  "PRIMEM" -> {"Greenwich", 0.}, "UNIT" -> {"Degree", 0.0174533}}

and if I just Import the shape file, it displays correctly on screen.

I would like to display the points from latlong within the county borders from demo.shp. I have not been able to figure out how.

I appreciate that this is as much a GIS question as it is a Mathematica question, but I hope somebody here can help.

Answer

The most likely cause of your problem is that you are swapping lat and long coordinates.

Your latlong definition in the .NB file provided goes like this:

latlong = {{40.660323`, -73.997952`}, {40.660489`, -73.99822`}, {40.654365`, -74.004113`},...

That's New York. Simply plotting without projection gives:

m1=Graphics@Point@latlong

Mathematica graphics

I seem to see Long Island and some other familiar features. Looks like a subway map.

Here is a publicly available SHP map of the subway lines:

Import["https://wfs.gc.cuny.edu/SRomalewski/MTA_GISdata/June2010_update/nyctsubwayroutes_100627.zip", "SHP"]

Mathematica graphics

Extracting some coordinates from that:

Cases[map, {_Real, _}, Infinity]

{{-74.015047, 40.703577}, {-74.015028, 40.703214}, {-74.014889, 40.702506}, ...

You can see that this has the latlongs in the reverse order. Plotting these points with your other latlong gives precisely the result you describe above.

Mathematica graphics

The solution is to map Reverse on these coordinates:

m2 = Graphics[{Red, Point@(Reverse /@ Cases[map, {_Real, _}, Infinity])}];
Show[m1,m2]

Mathematica graphics

Comments

plotting - Plot 4D data with color as 4th dimension

I have a list of 4D data (x position, y position, amplitude, wavelength). I want to plot x, y, and amplitude on a 3D plot and have the color of the points correspond to the wavelength. I have seen many examples using functions to define color but my wavelength cannot be expressed by an analytic function. Is there a simple way to do this? Answer Here a another possible way to visualize 4D data: data = Flatten[Table[{x, y, x^2 + y^2, Sin[x - y]}, {x, -Pi, Pi,Pi/10}, {y,-Pi,Pi, Pi/10}], 1]; You can use the function Point along with VertexColors . Now the points are places using the first three elements and the color is determined by the fourth. In this case I used Hue, but you can use whatever you prefer. Graphics3D[ Point[data[[All, 1 ;; 3]], VertexColors -> Hue /@ data[[All, 4]]], Axes -> True, BoxRatios -> {1, 1, 1/GoldenRatio}]

plotting - Filling between two spheres in SphericalPlot3D

Manipulate[ SphericalPlot3D[{1, 2 - n}, {θ, 0, Pi}, {ϕ, 0, 1.5 Pi}, Mesh -> None, PlotPoints -> 15, PlotRange -> {-2.2, 2.2}], {n, 0, 1}] I cant' seem to be able to make a filling between two spheres. I've already tried the obvious Filling -> {1 -> {2}} but Mathematica doesn't seem to like that option. Is there any easy way around this or ... Answer There is no built-in filling in SphericalPlot3D . One option is to use ParametricPlot3D to draw the surfaces between the two shells: Manipulate[ Show[SphericalPlot3D[{1, 2 - n}, {θ, 0, Pi}, {ϕ, 0, 1.5 Pi}, PlotPoints -> 15, PlotRange -> {-2.2, 2.2}], ParametricPlot3D[{ r {Sin[t] Cos[1.5 Pi], Sin[t] Sin[1.5 Pi], Cos[t]}, r {Sin[t] Cos[0 Pi], Sin[t] Sin[0 Pi], Cos[t]}}, {r, 1, 2 - n}, {t, 0, Pi}, PlotStyle -> Yellow, Mesh -> {2, 15}]], {n, 0, 1}]

plotting - Mathematica: 3D plot based on combined 2D graphs

I have several sigmoidal fits to 3 different datasets, with mean fit predictions plus the 95% confidence limits (not symmetrical around the mean) and the actual data. I would now like to show these different 2D plots projected in 3D as in but then using proper perspective. In the link here they give some solutions to combine the plots using isometric perspective, but I would like to use proper 3 point perspective. Any thoughts? Also any way to show the mean points per time point for each series plus or minus the standard error on the mean would be cool too, either using points+vertical bars, or using spheres plus tubes. Below are some test data and the fit function I am using. Note that I am working on a logit(proportion) scale and that the final vertical scale is Log10(percentage). (* some test data *) data = Table[Null, {i, 4}]; data[[1]] = {{1, -5.8}, {2, -5.4}, {3, -0.8}, {4, -0.2}, {5, 4.6}, {1, -6.4}, {2, -5.6}, {3, -0.7}, {4, 0.04}, {5, 1.0}, {1, -6.8}, {2, -4.7}, {3, -1....

Blog

Search This Blog