Read geospatial table from vector data file
Read Shapefile as Geospatial Table
Read a shapefile, containing a network of roads in Concord, MA, into the workspace as a geospatial table.
T = readgeotable("concord_roads.shp");
Shape variable of the table contains information about the road shapes, including the coordinate reference system (CRS). The road shapes in this shapefile use a projected CRS.
ans = projcrs with properties: Name: "NAD83 / Massachusetts Mainland" GeographicCRS: [1x1 geocrs] ProjectionMethod: "Lambert Conic Conformal (2SP)" LengthUnit: "meter" ProjectionParameters: [1x1 map.crs.ProjectionParameters]
Display the roads on a map.
mapshow(T) xlabel("x (meters)") ylabel("y (meters)")
Read Shapefile with No Projection File
An optional projection file (
.prj) determines the coordinate system type for a shapefile. When your shapefile does not have a projection file, but you know the coordinate system type, you can specify it by using the
CoordinateSystemType name-value argument.
Read a shapefile called
tsunamis.shp, containing information about tsunami events, into the workspace. The metadata accompanying the file indicates that the shapefile uses geographic coordinates.
T = readgeotable("tsunamis.shp",CoordinateSystemType="geographic");
Shape variable of the geospatial table. The tsunami source locations are stored as points.
ans = 162×1 geopointshape array with properties: NumPoints: [162×1 double] Latitude: [162×1 double] Longitude: [162×1 double] Geometry: "point" CoordinateSystemType: "geographic" GeographicCRS: 
Plot the source locations on a web map.
Read Layers from GPX Files
GPX files can contain up to five layers: waypoints, tracks, track points, routes, and route points. When you read a layer containing track points or route points, the geospatial table contains an ID variable that associates the points with a track or route.
Import the tracks layer of a GPX file with two tracks. The
Shape variable for each track is a
T = readgeotable("sample_tracks.gpx",Layer="tracks")
T=2×3 table Shape Name Number ____________ _________________________________________________________________________________________ ______ geolineshape "Track logs from walking the perimeter of the MathWorks campus in Natick on May 21, 2007" 1 geolineshape "Track logs from biking from Concord to the MathWorks campus in Natick on June 30, 2011" 2
View the shape of each track. The first track has one segment and the second track has five segments.
ans = geolineshape with properties: NumParts: 1 Geometry: "line" CoordinateSystemType: "geographic" GeographicCRS: [1×1 geocrs]
ans = geolineshape with properties: NumParts: 5 Geometry: "line" CoordinateSystemType: "geographic" GeographicCRS: [1×1 geocrs]
Import the track points layer. The
Shape variable for each point is a
T2 = readgeotable("sample_tracks.gpx",Layer="track_points"); T2.Shape
ans = 2586×1 geopointshape array with properties: NumPoints: [2586×1 double] Latitude: [2586×1 double] Longitude: [2586×1 double] Geometry: "point" CoordinateSystemType: "geographic" GeographicCRS: [1×1 geocrs]
Create a subtable that contains points in the second track only. For this file, points in the second track have a
TrackFID value of
rows = (T2.TrackFID == 1); T3 = T2(rows,:);
Plot the points in the subtable as a blue line.
Read GeoJSON File from Web Service
Read GeoJSON data from a website and save it in the file
storms.geojson. The data contains day 1 convective outlooks from the NOAA/NWS Storm Prediction Center. For more information about convective outlooks, see . For links to the data, see .
Read the data into a geospatial table. If the file contains no data for the
readgeotable function to read, such as when there are no severe thunderstorm threats, create a geospatial table with an empty polygon shape instead.
try GT = readgeotable("storms.geojson"); catch GT = table(geopolyshape,"No Data","none",VariableNames=["Shape" "LABEL2" "fill"]); end
Shape variable of the geospatial table. The table stores the geographic areas as polygons.
ans=3×1 object 3×1 geopolyshape array with properties: NumRegions: [3×1 double] NumHoles: [3×1 double] Geometry: "polygon" CoordinateSystemType: "geographic" GeographicCRS: [1×1 geocrs]
Day 1 convective outlooks change from day to day, so your results can be different.
Display the convective outlooks over a satellite basemap. To create a legend from the thunderstorm risk categories, plot each row of the table as a separate polygon.
figure geobasemap satellite hold on for k = 1:height(GT) row = GT(k,:); geoplot(row,"DisplayName",row.LABEL2,"FaceColor",row.fill) end legend alpha(0.6)
Add a title, including the access date.
dt = datetime("today",Format="MMMM d, yyyy"); title("Day 1 Convective Outlooks",dt)
 "SPC Products." NOAA/National Weather Service Storm Prediction Center. Accessed December 6, 2021. https://www.spc.noaa.gov/misc/about.html.
 "SPC Shapefile/KML/KMZ Links." NOAA/National Weather Service Storm Prediction Center. Accessed December 6, 2021. https://www.spc.noaa.gov/gis/.
filename — Name of file to read
character vector | string scalar
Name of the file to read, specified as a character vector or string scalar. The form
filename depends on the location of your file.
If the file is in your current folder or in a folder on the MATLAB® path, then specify the name of the file, such as
If the file is not in the current folder or in a folder on the MATLAB path, then specify the full or relative path name, such as
For a list of supported file formats, see Supported Formats and Extensions.
To read an Esri file geodatabase, you must either specify the full or relative path name or include the geodatabase in your current folder.
Specify optional pairs of arguments as
the argument name and
Value is the corresponding value.
Name-value arguments must appear after other arguments, but the order of the
pairs does not matter.
the track points layer from the GPX file.
Layer — Layer to read
positive integer | string scalar | character vector
Layer to read when the file contains multiple layers, specified as a positive integer, a string scalar, or a character vector. If you specify an integer, then it must be less than or equal to the number of vector layers in the file.
The layers contained in a file depend on the file format. Shapefiles have one layer. The content of Esri file geodatabases and GeoJSON files determines the number of layers and the names of the layers. Each folder and subfolder of KML files corresponds to layers, and the folder names match the layer names.
For GPX files, specify the layer as one of these options:
"tracks"— Track lines.
"track_points"— Track points. When you read track points, the geospatial table contains an ID variable,
TrackFID, that associates each point with a track.
"routes"— Route lines.
"route_points"— Route points. When you read route points, the geospatial table contains an ID variable,
RouteFID, that associates each point with a route.
CoordinateSystemType — Coordinate system type
"auto" (default) |
Coordinate system type, specified as one of these values:
Specify the coordinate system type when the
function is unable to detect the coordinate system type.
For shapefiles, the coordinate system type is determined by an optional projection
.prj). If your shapefile does not have a projection file, you
can try to determine the coordinate system type using one of these options:
Refer to the metadata.
Ask your data provider.
Return information about the shapefile as a structure by using the
shapeinfofunction. Then, view the limits of the data by querying the
BoundingBoxfield of the structure. The limits might help you predict the coordinate system type.
VariableNamingRule — Flag to preserve variable names
"preserve" (default) |
Flag to preserve variable names, specified as one of these options:
"preserve"— Preserve variable names that are not valid MATLAB identifiers, such as variable names that include spaces and non-ASCII characters.
"modify"— Convert invalid variable names, as identified by the
isvarnamefunction, to valid MATLAB identifiers.
T — Geospatial table
Geospatial table, returned as a geospatial table. A geospatial table is a
table object with a
Shape variable and attribute
Shapevariable contains 2-D information about point, line, and polygon shapes. The
Shapevariable can contain combinations of shape types. All the shapes have the same coordinate reference system (CRS).
The attribute variables contain data such as names, classifications, and measurements.
Supported Formats and Extensions
readgeotable function supports these file
formats and extensions.
|Esri file geodatabase|
Some file formats consist of a main file and multiple supporting files. For example,
shapefiles include a main file (
.shp), an index file
.shx), and an attribute file (
.dbf). When you read
a data file with supporting files using the
specify the extension of the main file.
When the file contains 3-D points, lines, or polygons, the function reads only the 2-D
information into the
Shape variable of the geospatial table.
For GeoJSON files, all attributes apply to all rows in the geospatial table, even when the GeoJSON file does not apply an attribute to all elements. When the file does not apply an attribute to an element, the corresponding cell in the geospatial table contains a missing data value.
For GPX files, Garmin® extensions are not supported.
For KML files, the
readgeotable function reads only shapes, names,
and descriptions into the geospatial table.