Ran into an interesting problem with the behavior of the text annotation functions in cartopy following the documentation which I don't think should be doing this - believe its related to how the text method takes the transform and applies it, perhaps similar to the issue shown here for .annotate (Why the annotate worked unexpected here in cartopy?). Basically no matter what is specified in terms of lat/lon and the transform it always plots at the center point of the plot. Code sample below:
import cartopy.crs as ccrs
import cartopy.feature as cfeature
import cartopy.io.shapereader as shpreader
from matplotlib.colors import BoundaryNorm
import matplotlib.pyplot as plt
import matplotlib.patches as mpatches
import matplotlib.patheffects as path_effects
def basic_map(proj):
fig = plt.figure(figsize=(12, 8))
view = fig.add_axes([0, 0, 1, 1], projection=proj)
view.set_extent([-120, -73, 23, 50])
view.add_feature(cfeature.STATES.with_scale('50m'))
view.add_feature(cfeature.OCEAN.with_scale('50m'),facecolor='white')
view.add_feature(cfeature.COASTLINE.with_scale('50m'))
view.add_feature(cfeature.BORDERS, linestyle=':')
return fig, view
proj = ccrs.AlbersEqualArea(central_longitude=-97.0000, central_latitude=38.0000)
fig, view = basic_map(prod)
view.text(-70,41, 'Northeast', color='black', fontsize=20, fontweight='bold',transform=proj,
path_effects=[path_effects.withSimplePatchShadow(),path_effects.PathPatchEffect(edgecolor='black', linewidth=0.6,facecolor='black')])
Related
I've seen a few other questions on this topic, but the library has changed enough that the answers to those no longer seem to apply.
Rasterio used to include an example for plotting a rasterio raster on a Cartopy GeoAxes. The example went roughly like this:
import matplotlib.pyplot as plt
import rasterio
from rasterio import plot
import cartopy
import cartopy.crs as ccrs
world = rasterio.open(r"../tests/data/world.rgb.tif")
fig = plt.figure(figsize=(20, 12))
ax = plt.axes(projection=ccrs.InterruptedGoodeHomolosine())
ax.set_global()
plot.show(world, origin='upper', transform=ccrs.PlateCarree(), interpolation=None, ax=ax)
ax.coastlines()
ax.add_feature(cartopy.feature.BORDERS)
However, this code no longer draws the raster. Instead, I get something like this:
It should look like this:
When I asked about this in the rasterio issues tracker, they told me the example was deprecated (and deleted the example). Still, I wonder if there's some way to do what I'm trying to do. Can anyone point me in the right direction?
I think you may want to read the data to a numpy.ndarray and plot it using ax.imshow, where ax is your cartopy.GeoAxes (as you have it already). I offer an example of what I mean, below.
I clipped a small chunk of Landsat surface temperature and some agricultural fields for this example. Get them on this drive link.
Note fields are in WGS 84 (epsg 4326), Landsat image is in UTM Zone 12 (epsg 32612), and I want my map in Lambert Conformal Conic. Cartopy makes this easy.
import numpy as np
import cartopy.crs as ccrs
from cartopy.io.shapereader import Reader
from cartopy.feature import ShapelyFeature
import rasterio
import matplotlib.pyplot as plt
def cartopy_example(raster, shapefile):
with rasterio.open(raster, 'r') as src:
raster_crs = src.crs
left, bottom, right, top = src.bounds
landsat = src.read()[0, :, :]
landsat = np.ma.masked_where(landsat <= 0,
landsat,
copy=True)
landsat = (landsat - np.min(landsat)) / (np.max(landsat) - np.min(landsat))
proj = ccrs.LambertConformal(central_latitude=40,
central_longitude=-110)
fig = plt.figure(figsize=(20, 16))
ax = plt.axes(projection=proj)
ax.set_extent([-110.8, -110.4, 45.3, 45.6], crs=ccrs.PlateCarree())
shape_feature = ShapelyFeature(Reader(shapefile).geometries(),
ccrs.PlateCarree(), edgecolor='blue')
ax.add_feature(shape_feature, facecolor='none')
ax.imshow(landsat, transform=ccrs.UTM(raster_crs['zone']),
cmap='inferno',
extent=(left, right, bottom, top))
plt.savefig('surface_temp.png')
feature_source = 'fields.shp'
raster_source = 'surface_temperature_32612.tif'
cartopy_example(raster_source, feature_source)
The trick with Cartopy is to remember to use the projection keyword for your axes object, as this renders the map in a nice projection of your choice (LCC in my case). Use transform keyword to indicate what projection system your data is in, so Cartopy knows how to render it.
No need of rasterio. Get a bluemarble image, then plot it.
Here is the working code:
import cartopy
import matplotlib.pyplot as plt
import cartopy.crs as ccrs
fig = plt.figure(figsize=(10, 5))
ax = plt.axes(projection=ccrs.InterruptedGoodeHomolosine())
# source of the image:
# https://eoimages.gsfc.nasa.gov/images/imagerecords/73000/73909/world.topo.bathy.200412.3x5400x2700.jpg
fname = "./world.topo.bathy.200412.3x5400x2700.jpg"
img_origin = 'lower'
img = plt.imread(fname)
img = img[::-1]
ax.imshow(img, origin=img_origin, transform=ccrs.PlateCarree(), extent=[-180, 180, -90, 90])
ax.coastlines()
ax.add_feature(cartopy.feature.BORDERS)
ax.set_global()
plt.show()
The output plot:
I want to know why IDE pycharm(2018.1.1) highlighting the code ax.set_zlabel('Z')
with hint unresolved attribute reference 'set_zlabel' for class Axes
but the code run normally.
these are import packages
import numpy as np
from scipy.stats import multivariate_normal
from sklearn.mixture import GaussianMixture
from mpl_toolkits.mplot3d import Axes3D
import matplotlib as mpl
import matplotlib.pyplot as plt
from sklearn.metrics.pairwise import pairwise_distances_argmin
Interestingly, PyCharm doesn't complain for me with the following code, but I'm guessing that's an effect of a newer version (I'm using matplotlib 3.0.0 and PyCharm 2018.1.4).
In any case, I believe the problem comes from the fact that PyCharm might not know that e.g. add_subplot() can return different objects depending on the projection used.
fig = plt.figure()
ax1 = fig.add_subplot(111)
type(ax1)
>>> matplotlib.axes._subplots.AxesSubplot
from mpl_toolkits.mplot3d import Axes3D
fig = plt.figure()
ax1 = fig.add_subplot(111, projection="3d")
type(ax1)
>>> matplotlib.axes._subplots.Axes3DSubplot
However, you can help PyCharm by providing "type hints" (see https://www.jetbrains.com/help/pycharm/type-hinting-in-product.html)
from mpl_toolkits.mplot3d import Axes3D
fig = plt.figure()
ax1 = fig.add_subplot(111, projection="3d") # type: Axes3D
ax1.set_zlabel("z-label")
or, if using Python 3+:
ax1: Axes3D = fig.add_subplot(111, projection="3d")
import numpy as np
import os.path
from skimage.io import imread
from skimage import data_dir
img = imread(os.path.join(data_dir, 'checker_bilevel.png'))
import matplotlib.pyplot as plt
#plt.imshow(img, cmap='Blues')
#plt.show()
imgT = img.T
plt.figure(1)
plt.imshow(imgT,cmap='Greys')
#plt.show()
imgR = img.reshape(20,5)
plt.figure(2)
plt.imshow(imgR,cmap='Blues')
plt.show(1)
I read that plt.figure() will create or assign the image a new ID if not explicitly given one. So here, I have given the two figures, ID 1 & 2 respectively. Now I wish to see only one one of the image.
I tried plt.show(1) epecting ONLY the first image will be displayed but both of them are.
What should I write to get only one?
plt.clf() will clear the figure
import matplotlib.pyplot as plt
plt.plot(range(10), 'r')
plt.clf()
plt.plot(range(12), 'g--')
plt.show()
plt.show will show all the figures created. The argument you forces the figure to be shown in a non-blocking way. If you only want to show a particular figure you can write a wrapper function.
import matplotlib.pyplot as plt
figures = [plt.subplots() for i in range(5)]
def show(figNum, figures):
if plt.fignum_exists(figNum):
fig = [f[0] for f in figures if f[0].number == figNum][0]
fig.show()
else:
print('figure not found')
Using basemap I used to add my custom boundary shapefile like this:
map = Basemap(..)
map.readshapefile(file.shp, 'attribute', drawbounds=True)
How can I do the same using cartopy?
I tried this:
ax.add_feature(cfeature.shapereader.Polygon('file.shp'))
but that's not working..
There is currently no ShapefileFeature class (though that would be easy enough to create, and would probably make a lot of sense) so if you really want to use the feature interface then there is a hoop to jump through:
import matplotlib.pyplot as plt
import cartopy.crs as ccrs
from cartopy.io.shapereader import Reader
from cartopy.feature import ShapelyFeature
fname = '50m_glaciated_areas.shp'
ax = plt.axes(projection=ccrs.Robinson())
shape_feature = ShapelyFeature(Reader(fname).geometries(),
ccrs.PlateCarree(), facecolor='none')
ax.add_feature(shape_feature)
plt.show()
Alternatively, you could just use the add_geometries method, which is not making use of the feature interface (and so, in the future, will not be optimised to read from disk only the geometries which are actually being drawn as would be the case with a ShapefileFeature class):
import matplotlib.pyplot as plt
import cartopy.crs as ccrs
from cartopy.io.shapereader import Reader
fname = '50m_glaciated_areas.shp'
ax = plt.axes(projection=ccrs.Robinson())
ax.add_geometries(Reader(fname).geometries(),
ccrs.PlateCarree(),
facecolor='white', hatch='xxxx')
plt.show()
HTH
I received the following email and wanted to make sure the answer to this question was available to everybody:
Hi,
I would like to setup a simple latitude longitude map, using cartopy, which crosses the dateline and shows east Asia on the left hand side with the west of North America on the right. The following google map is roughly what I am after:
https://maps.google.co.uk/?ll=56.559482,-175.253906&spn=47.333523,133.066406&t=m&z=4
Can this be done with Cartopy?
Good question. This is probably something which will come up time-and-time again, so I will go through this step-by-step before actually answering your specific question. For future reference, the following examples were written with cartopy v0.5.
Firstly, it is important to note that the default "latitude longitude" (or more technically PlateCarree) projection works in the forward range of -180 to 180. This means that you cannot plot the standard PlateCarree projection beyond this. There are several good reasons for this, most of which boil down to the fact that cartopy would have to do a lot more work when projecting both vectors and rasters (simple coastlines for example). Unfortunately the plot you are trying to produce requires precisely this functionality. To put this limitation into pictures, the default PlateCarree projection looks like:
import cartopy.crs as ccrs
import matplotlib.pyplot as plt
proj = ccrs.PlateCarree(central_longitude=0)
ax1 = plt.axes(projection=proj)
ax1.stock_img()
plt.title('Global')
plt.show()
Any single rectangle that you can draw on this map can legally be a zoomed in area (there is some slightly more advanced code in here, but the picture is worth a 1000 words):
import cartopy.crs as ccrs
import matplotlib.pyplot as plt
import shapely.geometry as sgeom
box = sgeom.box(minx=-90, maxx=45, miny=15, maxy=70)
x0, y0, x1, y1 = box.bounds
proj = ccrs.PlateCarree(central_longitude=0)
ax1 = plt.subplot(211, projection=proj)
ax1.stock_img()
ax1.add_geometries([box], proj, facecolor='coral',
edgecolor='black', alpha=0.5)
plt.title('Global')
ax2 = plt.subplot(212, projection=proj)
ax2.stock_img()
ax2.set_extent([x0, x1, y0, y1], proj)
plt.title('Zoomed in area')
plt.show()
Unfortunately the plot you want would require 2 rectangles with this projection:
import cartopy.crs as ccrs
import matplotlib.pyplot as plt
import shapely.geometry as sgeom
box = sgeom.box(minx=120, maxx=260, miny=15, maxy=80)
proj = ccrs.PlateCarree(central_longitude=0)
ax1 = plt.axes(projection=proj)
ax1.stock_img()
ax1.add_geometries([box], proj, facecolor='coral',
edgecolor='black', alpha=0.5)
plt.title('Target area')
plt.show()
Hence it is not possible to draw a map that crosses the dateline using the standard PlateCarree definition. Instead we could change the PlateCarree definition's central longitude to allow a single box to be drawn of the area we are targeting:
import cartopy.crs as ccrs
import matplotlib.pyplot as plt
import shapely.geometry as sgeom
box = sgeom.box(minx=120, maxx=260, miny=15, maxy=80)
x0, y0, x1, y1 = box.bounds
proj = ccrs.PlateCarree(central_longitude=180)
box_proj = ccrs.PlateCarree(central_longitude=0)
ax1 = plt.subplot(211, projection=proj)
ax1.stock_img()
ax1.add_geometries([box], box_proj, facecolor='coral',
edgecolor='black', alpha=0.5)
plt.title('Global')
ax2 = plt.subplot(212, projection=proj)
ax2.stock_img()
ax2.set_extent([x0, x1, y0, y1], box_proj)
plt.title('Zoomed in area')
plt.show()
Hopefully that shows you what it is you have to do to achieve your target map, the code above might be a little complex to achieve your goal, so to simplify slightly, the code I would write to produce the plot you want would be something like:
import cartopy.feature
import cartopy.crs as ccrs
import matplotlib.pyplot as plt
ax = plt.axes(projection=ccrs.PlateCarree(central_longitude=180))
ax.set_extent([120, 260, 15, 80], crs=ccrs.PlateCarree())
# add some features to make the map a little more polished
ax.add_feature(cartopy.feature.LAND)
ax.add_feature(cartopy.feature.OCEAN)
ax.coastlines('50m')
plt.show()
This was a long answer, hopefully I have not only answered the question, but made some of the more complex details of map production and cartopy more clear to help smooth any future problems you may have.
Cheers,
For more details of above benjimin's comment,
import numpy as np
import matplotlib.pyplot as plt
import cartopy.crs as ccrs
from cartopy.mpl.gridliner import LONGITUDE_FORMATTER, LATITUDE_FORMATTER
from matplotlib.ticker import AutoMinorLocator, FixedLocator, MultipleLocator
def map_common(ax1,gl_loc=[True,True,False,True],gl_lon_info=range(-180,180,60),gl_dlat=30):
ax1.coastlines(color='silver',linewidth=1.)
gl = ax1.gridlines(crs=ccrs.PlateCarree(), draw_labels=True,
linewidth=0.6, color='gray', alpha=0.5, linestyle='--')
gl.ylabels_left = gl_loc[0]
gl.ylabels_right = gl_loc[1]
gl.xlabels_top = gl_loc[2]
gl.xlabels_bottom = gl_loc[3]
gl.xlocator = FixedLocator(gl_lon_info)
gl.ylocator = MultipleLocator(gl_dlat)
gl.xformatter = LONGITUDE_FORMATTER
gl.yformatter = LATITUDE_FORMATTER
gl.xlabel_style = {'size': 11, 'color': 'k'}
gl.ylabel_style = {'size': 11, 'color': 'k'}
lon_boundary=np.arange(-240,-60,1.)
lat_boundary=np.arange(15,75,1.)
data=np.ones([lat_boundary.shape[0]-1,lon_boundary.shape[0]-1]) ## Data dimension is 1 less than boundaries
data=data*lat_boundary[:-1,None]
lon_offset=-150 ##
x,y=np.meshgrid(lon_boundary-lon_offset,lat_boundary)
fig=plt.figure()
fig.set_size_inches(7.5,5) ## (xsize, ysize)
ax1=fig.add_subplot(111,projection=ccrs.PlateCarree(central_longitude=lon_offset))
ax1.set_extent([-250,-50,10,80],crs=ccrs.PlateCarree())
props=dict(vmin=0,vmax=90,cmap=plt.cm.get_cmap('bone'),alpha=0.8)
cs=ax1.pcolormesh(x,y,data,**props)
ax1.set_title('Lon_Offset=-90')
map_common(ax1,gl_lon_info=[-180,-120,-60,120,],gl_dlat=15)
fnout='./map_over_dateline.png'
#plt.show()
plt.savefig(fnout,bbox_inches='tight',dpi=150)
Output of this program