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Questions tagged [gis]

A Geographic Information System (GIS) captures, stores, analyzes, manages, and presents data that are linked to location(s). The GIS Stack Exchange should be considered for questions with this tag.

According to Wikipedia:

A geographic information system (GIS), geographical information system, or geospatial information system is any system that captures, stores, analyzes, manages, and presents data that are linked to location(s). In the simplest terms, GIS is the merging of cartography, statistical analysis, and database technology.

There is a Stack Exchange site devoted to Geographic Information Systems.

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How to manipulate tmap legend?

I'm creating a thematic map of percent change per year for bird species. here is the code I have: tm_shape(grid83)+ tm_fill("trend", title = "Percent change per Year", textNA = "None counted", style="fixed", breaks=c(-Inf, -1.5, -0.25, 0.25,…
wallflower
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Finding adjacent polygons in R (neighbors)

I'm starting with a SpatialPolygonsDataFrame which has the data to create a map of the districts of Ghana (available at http://www.diva-gis.org/datadown). I'm trying to create a matrix with the names of the districts as row and column names and…
Megan E.
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Map Routing, a la Google Maps?

I've always been intrigued by Map Routing, but I've never found any good introductory (or even advanced!) level tutorials on it. Does anybody have any pointers, hints, etc? Update: I'm primarily looking for pointers as to how a map system is…
Mark Harrison
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Good examples of MapServer / OpenLayers

I want to convince some clients to use MapServer and OpenLayers. Please can anyone suggest attractive websites to show off the possiblities! The clients will be impressed by: A density map (otherwise known as a heat map, colour-shaded grid…
MarkJ
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why can't I import geopandas?

My only line of code is import geopandas and it gives me the error OSError: Could not find libspatialindex_c library file has anyone encountered this before? my script was working just fine until this error came up. **Note that rtree module not…
jrowley
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Distance from Lat/Lng point to Minor Arc segment

I need to calculate the shortest distance from a lat/lng GPS point P to a line segment described by 2 other lat/lng GPS points A and B. 'Cross-track distance' helps me to calculate the shortest distance between P and the great circle described by A…
ChrisDekker
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6 answers

Python, GEOS and Shapely on Windows 64

When trying to install Shapely on my Windows 64bit computer, I cannot get the GEOS library to work. So far, I have run the OSGeo4W installer from which I installed GDAL (I believe the geos library is included in that package). After that, I checked…
Juan Carlos Coto
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Algorithm for finding nearby points?

Given a set of several million points with x,y coordinates, what is the algorithm of choice for quickly finding the top 1000 nearest points from a location? "Quickly" here means about 100ms on a home computer. Brute force would mean doing millions…
Bemmu
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Get street address at lat/long pair

I've seen that it's possible to get the latitude and longitude (geocoding, like in Google Maps API) from a street address, but is it possible to do the reverse and get the street address when you know what the lat/long already is? The application…
Chris Wenham
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How to use Google Maps API in leaflet-cloudmade

Is there any way to integrate Google Maps with leaflet-cloudmade? I mean, I don't want to use the original cloudmade map, but I want to use Google Maps instead. I want to show a map of Alaska (not many roads there). If I use a cloudmade map, it…
goFrendiAsgard
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ST_DWithin takes parameter as degree , not meters , why?

The ST_DWithin document says , the third parameter(distance) is in meters. But when I execute some query , it seems it takes the 3rd parameter as 'degree' ? Here is my simplified table structure : > \d+ theuser; Table…
smallufo
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What is the quickest way to find the shortest cartesian distance between two polygons

I have 1 red polygon say and 50 randomly placed blue polygons - they are situated in geographical 2D space. What is the quickest/speediest algorithim to find the the shortest distance between a red polygon and its nearest blue polygon? Bear in mind…
Vidar
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5 answers

Layer Ordering in leaflet.js

How can I force a new layer added to the map in Leaflet to be the first over the basemap? I could not find a method to easily change the order of the layers, which is a very basic GIS feature. Am I missing something?
user1249791
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Matplotlib imshow offset to match axis?

I'm plotting a bunch of UTM coordinates using a matplotlib.pyplot.scatter. I also have a background air photo that I know matches the extent of the figure exactly. When I plot my data and set the axis I can display the scatter correctly. If I plot…
cds-mewald
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is Boost.Geometry mature enough?

I've been recently hired by a GIS company to rewrite their old geomatics libraries. So I'm currently looking for a good computational geometry library. I've seen CGAL, which is amazing, but my boss wants something free. So I'm now checking…
undu
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