I've two netcdf files containing both unstructured grids. The first grid has 3 vertices per face and the second has 4 vertices per face.
For the grid containing 3 vertices per face I can use matplotlib.tri for visualization (like triplot_demo.py:
import matplotlib.pyplot as plt
import matplotlib.tri as tri
import numpy as np
xy = np.asarray([
[-0.101, 0.872], [-0.080, 0.883], [-0.069, 0.888], [-0.054, 0.890],
[-0.045, 0.897], [-0.057, 0.895], [-0.073, 0.900], [-0.087, 0.898],
[-0.090, 0.904], [-0.069, 0.907], [-0.069, 0.921], [-0.080, 0.919],
[-0.073, 0.928], [-0.052, 0.930], [-0.048, 0.942], [-0.062, 0.949],
[-0.054, 0.958], [-0.069, 0.954], [-0.087, 0.952], [-0.087, 0.959],
[-0.080, 0.966], [-0.085, 0.973], [-0.087, 0.965], [-0.097, 0.965],
[-0.097, 0.975], [-0.092, 0.984], [-0.101, 0.980], [-0.108, 0.980],
[-0.104, 0.987], [-0.102, 0.993], [-0.115, 1.001], [-0.099, 0.996],
[-0.101, 1.007], [-0.090, 1.010], [-0.087, 1.021], [-0.069, 1.021],
[-0.052, 1.022], [-0.052, 1.017], [-0.069, 1.010], [-0.064, 1.005],
[-0.048, 1.005], [-0.031, 1.005], [-0.031, 0.996], [-0.040, 0.987],
[-0.045, 0.980], [-0.052, 0.975], [-0.040, 0.973], [-0.026, 0.968],
[-0.020, 0.954], [-0.006, 0.947], [ 0.003, 0.935], [ 0.006, 0.926],
[ 0.005, 0.921], [ 0.022, 0.923], [ 0.033, 0.912], [ 0.029, 0.905],
[ 0.017, 0.900], [ 0.012, 0.895], [ 0.027, 0.893], [ 0.019, 0.886],
[ 0.001, 0.883], [-0.012, 0.884], [-0.029, 0.883], [-0.038, 0.879],
[-0.057, 0.881], [-0.062, 0.876], [-0.078, 0.876], [-0.087, 0.872],
[-0.030, 0.907], [-0.007, 0.905], [-0.057, 0.916], [-0.025, 0.933],
[-0.077, 0.990], [-0.059, 0.993]])
x = np.degrees(xy[:, 0])
y = np.degrees(xy[:, 1])
triangles = np.asarray([
[65, 44, 20],
[65, 60, 44]])
triang = tri.Triangulation(x, y, triangles)
plt.figure()
plt.gca().set_aspect('equal')
plt.triplot(triang, 'go-', lw=1.0)
plt.title('triplot of user-specified triangulation')
plt.xlabel('Longitude (degrees)')
plt.ylabel('Latitude (degrees)')
plt.show()
-- indices of the related point annotated afterwards
BUT how to visualize the unstructured grid containing 4 vertices per face (quadrilaterals)? Following the previous exapmle, my faces looks like:
quatrang = np.asarray([
[65, 60, 44, 20]])
Obviously trying tri.Triangulation doesn't work:
quatr = tri.Triangulation(x, y, quatrang)
ValueError: triangles must be a (?,3) array
I cannot find anything in the matplotlib libraries regarding 4 vertices per face. Any help is greatly appreciated..
EDIT: Changed the question based upon a minimal, complete and verifiable example
As commented already, since there is no Quatrangulation or simiar, there is no standard way to plot a a similar plot as triplot with four points per shape in matplotlib.
Of course you could triangulate your mesh again to obtain 2 triangles per quadrilateral. Or, you can plot a PolyCollection of the shapes, given their coordinates in space. The following shows the latter, defining a quatplot function which takes the coordinates and the indices of the vertices as input and draws a PolyCollection of those to the axes.
import matplotlib.pyplot as plt
import numpy as np
import matplotlib.collections
xy = np.asarray([
[-0.101, 0.872], [-0.080, 0.883], [-0.069, 0.888], [-0.054, 0.890],
[-0.090, 0.904], [-0.069, 0.907], [-0.069, 0.921], [-0.080, 0.919],
[-0.080, 0.966], [-0.085, 0.973], [-0.087, 0.965], [-0.097, 0.965],
[-0.104, 0.987], [-0.102, 0.993], [-0.115, 1.001], [-0.099, 0.996],
[-0.052, 1.022], [-0.052, 1.017], [-0.069, 1.010], [-0.064, 1.005],
[-0.045, 0.980], [-0.052, 0.975], [-0.040, 0.973], [-0.026, 0.968],
[ 0.017, 0.900], [ 0.012, 0.895], [ 0.027, 0.893], [ 0.019, 0.886],
[ 0.001, 0.883], [-0.012, 0.884], [-0.029, 0.883], [-0.038, 0.879],
[-0.030, 0.907], [-0.007, 0.905], [-0.057, 0.916], [-0.025, 0.933],
[-0.077, 0.990], [-0.059, 0.993]])
x = np.degrees(xy[:, 0])
y = np.degrees(xy[:, 1])
quatrang = np.asarray([
[19,13,10,22], [35,7,3,28]])
def quatplot(x,y, quatrangles, ax=None, **kwargs):
if not ax: ax=plt.gca()
xy = np.c_[x,y]
verts=xy[quatrangles]
pc = matplotlib.collections.PolyCollection(verts, **kwargs)
ax.add_collection(pc)
ax.autoscale()
plt.figure()
plt.gca().set_aspect('equal')
quatplot(x,y, quatrang, ax=None, color="crimson", facecolor="None")
plt.plot(x,y, marker="o", ls="", color="crimson")
plt.title('quatplot of user-specified quatrangulation')
plt.xlabel('Longitude (degrees)')
plt.ylabel('Latitude (degrees)')
for i, (xi,yi) in enumerate(np.degrees(xy)):
plt.text(xi,yi,i, size=8)
plt.show()
Related
I am trying to export my surface plot into a .png file. For some reason, the saving plot does not correspond to the 3D orientation of the plot showed in spyder. Here is my code:
import csv
import matplotlib.pyplot as plt
from matplotlib import cm
from matplotlib.ticker import LinearLocator
import matplotlib as mpl
import numpy as np
with open(r'path', 'r') as f:
voltpertime = list(csv.reader(f, delimiter=","))
voltpertime = np.array(voltpertime[0:], dtype=np.float)
Z= np.flipud(voltpertime)
fig, ax = plt.subplots(subplot_kw={"projection": "3d"})
# Make data.
X = np.arange(1, 36, 1)
Y = np.arange(-4, 8, 0.1)
X, Y = np.meshgrid(X, Y)
# Plot the surface.
norm = mpl.colors.Normalize(vmin=-0.5, vmax=7)
surf = ax.plot_surface(X, Y, Z, cmap=cm.jet, linewidth=1, antialiased=False, norm=norm)
# Customize the z axis.
ax.set_zlim(-3, 7)
ax.zaxis.set_major_locator(LinearLocator(4))
ax.zaxis.set_major_formatter('{x:.02f}')
plt.colorbar(surf, shrink=0.5, aspect=5, label='current (nA)', pad = 0.1)
plt.yticks((-4, -2, 0, 2, 4, 6, 8), ("8", "6", "4", "2", "0", "-2", "-4"))
# rotate the axes and update
for angle in range(160, 360):
ax.view_init(35, angle)
plt.draw()
plt.pause(.001)
fig.savefig(r'path',
transparent = True, bbox_inches= 'tight', dpi=600, edgecolor= None)
plt.show()
Here is the plot in spyder:
and here is the plot when I save it:
I want to export the plot exactly how it appears in spyder.
Any idea?
Thanks
I'm currently trying to build an N-body simulation but I'm having a little trouble with plotting the results the way I'd like.
In the code below (with some example data for a few points in an orbit) I'm importing the position and time data and organizing it into a pandas dataframe. To create the 3D animation I use matplotlib's animation class, which works perfectly.
However, the usual way to set up an animation is limited in that you can't customize the points in each frame individually (please let me know if I'm wrong here :p). Since my animation is showing orbiting bodies I would like to vary their sizes and colors. To do that I essentially create a graph for each body and set it's color etc. When it gets to the update_graph function, I iterate over the n bodies, retrieve their individual (x,y,z) coordinates, and update their graphs.
import numpy as np
import matplotlib.pyplot as plt
from matplotlib import cm
from mpl_toolkits.mplot3d.axes3d import get_test_data
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.animation as animation
import pandas as pd
nbodies = 2
x = np.array([[1.50000000e-10, 0.00000000e+00, 0.00000000e+00],
[9.99950000e-01, 1.00000000e-02, 0.00000000e+00],
[4.28093585e-06, 3.22964816e-06, 0.00000000e+00],
[-4.16142210e-01, 9.09335149e-01, 0.00000000e+00],
[5.10376489e-06, 1.42204430e-05, 0.00000000e+00],
[-6.53770813e-01, -7.56722445e-01, 0.00000000e+00]])
t = np.array([0.01, 0.01, 2.0, 2.0, 4.0, 4.0])
tt = np.array([0.01, 2.0, 4.0])
x = x.reshape((len(tt), nbodies, 3))
x_coords = x[:, :, 0].flatten()
y_coords = x[:, :, 1].flatten()
z_coords = x[:, :, 2].flatten()
df = pd.DataFrame({"time": t[:] ,"x" : x_coords, "y" : y_coords, "z" : z_coords})
print(df)
def update_graph(num):
data=df[df['time']==tt[num]] # x,y,z of all bodies at current time
for n in range(nbodies): # update graphs
data_n = data[data['x']==x_coords[int(num * nbodies) + n]] # x,y,z of body n
graph = graphs[n]
graph.set_data(data_n.x, data_n.y)
graph.set_3d_properties(data_n.z)
graphs[n] = graph
return graphs
plt.style.use('dark_background')
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
ax.set_xlabel('x (AU)')
ax.set_ylabel('y (AU)')
ax.set_zlabel('z (AU)')
plt.xlim(-1.5,1.5)
plt.ylim(-1.5,1.5)
# initialize
data=df[df['time']==0]
ms_list = [5, 1]
c_list = ['yellow', 'blue']
graphs = []
for n in range(nbodies):
graphs.append(ax.plot([], [], [], linestyle="", marker=".",
markersize=ms_list[n], color=c_list[n])[0])
ani = animation.FuncAnimation(fig, update_graph, len(tt),
interval=400, blit=True, repeat=True)
plt.show()
However, doing this gives me the following error:
Traceback (most recent call last):
File "/home/kris/anaconda3/lib/python3.7/site-packages/matplotlib/backend_bases.py", line 1194, in _on_timer
ret = func(*args, **kwargs)
File "/home/kris/anaconda3/lib/python3.7/site-packages/matplotlib/animation.py", line 1447, in _step
still_going = Animation._step(self, *args)
File "/home/kris/anaconda3/lib/python3.7/site-packages/matplotlib/animation.py", line 1173, in _step
self._draw_next_frame(framedata, self._blit)
File "/home/kris/anaconda3/lib/python3.7/site-packages/matplotlib/animation.py", line 1193, in _draw_next_frame
self._post_draw(framedata, blit)
File "/home/kris/anaconda3/lib/python3.7/site-packages/matplotlib/animation.py", line 1216, in _post_draw
self._blit_draw(self._drawn_artists, self._blit_cache)
File "/home/kris/anaconda3/lib/python3.7/site-packages/matplotlib/animation.py", line 1231, in _blit_draw
a.axes.draw_artist(a)
File "/home/kris/anaconda3/lib/python3.7/site-packages/matplotlib/axes/_base.py", line 2661, in draw_artist
a.draw(self.figure._cachedRenderer)
File "/home/kris/anaconda3/lib/python3.7/site-packages/matplotlib/artist.py", line 38, in draw_wrapper
return draw(artist, renderer, *args, **kwargs)
File "/home/kris/anaconda3/lib/python3.7/site-packages/mpl_toolkits/mplot3d/art3d.py", line 202, in draw
xs, ys, zs = proj3d.proj_transform(xs3d, ys3d, zs3d, renderer.M)
File "/home/kris/anaconda3/lib/python3.7/site-packages/mpl_toolkits/mplot3d/proj3d.py", line 201, in proj_transform
vec = _vec_pad_ones(xs, ys, zs)
File "/home/kris/anaconda3/lib/python3.7/site-packages/mpl_toolkits/mplot3d/proj3d.py", line 189, in _vec_pad_ones
return np.array([xs, ys, zs, np.ones_like(xs)])
File "/home/kris/anaconda3/lib/python3.7/site-packages/pandas/core/series.py", line 871, in __getitem__
result = self.index.get_value(self, key)
File "/home/kris/anaconda3/lib/python3.7/site-packages/pandas/core/indexes/base.py", line 4405, in get_value
return self._engine.get_value(s, k, tz=getattr(series.dtype, "tz", None))
File "pandas/_libs/index.pyx", line 80, in pandas._libs.index.IndexEngine.get_value
File "pandas/_libs/index.pyx", line 90, in pandas._libs.index.IndexEngine.get_value
File "pandas/_libs/index.pyx", line 138, in pandas._libs.index.IndexEngine.get_loc
File "pandas/_libs/hashtable_class_helper.pxi", line 997, in pandas._libs.hashtable.Int64HashTable.get_item
File "pandas/_libs/hashtable_class_helper.pxi", line 1004, in pandas._libs.hashtable.Int64HashTable.get_item
KeyError: 0
Aborted (core dumped)
I'm not sure what this really means, but I do know the problem is something to do with updating the graphs with only one row of coordinates rather than all three. Because if I instead have
def update_graph(num):
data=df[df['time']==tt[num]] # x,y,z of all bodies at current time
for n in range(nbodies): # update graphs
#data_n = data[data['x']==x_coords[int(num * nbodies) + n]] # x,y,z of body n
graph = graphs[n]
graph.set_data(data.x, data.y) # using data rather than data_n here now
graph.set_3d_properties(data.z)
graphs[n] = graph
return graphs
it actually works, and plots three copies of the bodies with varying colors and sizes on top of each other as you would expect.
Any help would be much appreciated. Thanks!
I don't understand why you are going through a pandas DataFrame, when you seem to already have all the data you need in your numpy array. I couldn't reproduce the initial problem, by I propose this solution that uses pure numpy arrays, which may fix the problem:
import numpy as np
import matplotlib.pyplot as plt
from matplotlib import cm
from mpl_toolkits.mplot3d.axes3d import get_test_data
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.animation as animation
import pandas as pd
nbodies = 2
x = np.array([[1.50000000e-10, 0.00000000e+00, 0.00000000e+00],
[9.99950000e-01, 1.00000000e-02, 0.00000000e+00],
[4.28093585e-06, 3.22964816e-06, 0.00000000e+00],
[-4.16142210e-01, 9.09335149e-01, 0.00000000e+00],
[5.10376489e-06, 1.42204430e-05, 0.00000000e+00],
[-6.53770813e-01, -7.56722445e-01, 0.00000000e+00]])
t = np.array([0.01, 0.01, 2.0, 2.0, 4.0, 4.0])
tt = np.array([0.01, 2.0, 4.0])
x = x.reshape((len(tt), nbodies, 3))
def update_graph(i):
data = x[i, :, :] # x,y,z of all bodies at current time
for body, graph in zip(data, graphs): # update graphs
graph.set_data(body[0], body[1])
graph.set_3d_properties(body[2])
return graphs
plt.style.use('dark_background')
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
ax.set_xlabel('x (AU)')
ax.set_ylabel('y (AU)')
ax.set_zlabel('z (AU)')
plt.xlim(-1.5, 1.5)
plt.ylim(-1.5, 1.5)
# initialize
ms_list = [50, 10]
c_list = ['yellow', 'blue']
graphs = []
for n in range(nbodies):
graphs.append(ax.plot([], [], [], linestyle="", marker=".",
markersize=ms_list[n], color=c_list[n])[0])
ani = animation.FuncAnimation(fig, func=update_graph, frames=len(tt),
interval=400, blit=True, repeat=True)
plt.show()
I have a file 'mydata.tmp' which contains 3 colums like this:
3.81107 0.624698 0.000331622
3.86505 0.624698 0.000131237
3.91903 0.624698 5.15136e-05
3.97301 0.624698 1.93627e-05
1.32802 0.874721 1.59245
1.382 0.874721 1.542
1.43598 0.874721 1.572
1.48996 0.874721 4.27933
etc.
Then I want to make a heatmap color plot where the first two columns are coordinates, and the third column are the values of that coordinates.
Also, I would like to set the third column in log scale.
I have done this
import pandas as pd
import matplotlib.pyplot as plt
import scipy.interpolate
import numpy as np
import matplotlib.colors as colors
# import data
df = pd.read_csv('mydata.tmp', delim_whitespace=True,
comment='#',header=None,
names=['1','2','3'])
x = df['1']
y = df['2']
z = df['3']
spacing = 500
xi, yi = np.linspace(x.min(), x.max(), spacing), np.linspace(y.min(),
y.max(), spacing)
XI, YI = np.meshgrid(xi, yi)
rbf = scipy.interpolate.Rbf(x, y, z, function='linear')
ZI = rbf(XI, YI)
fig, ax = plt.subplots()
sc = ax.imshow(ZI, vmin=z.min(), vmax=z.max(), origin='lower',
extent=[x.min(), x.max(), y.min(),
y.max()], cmap="GnBu", norm=colors.LogNorm(vmin=ZI.min(),
vmax=ZI.max()))
fig.colorbar(sc, ax=ax, fraction=0.05, pad=0.01)
plt.show()
And I get this Image
which has all these empty pixels.
I am looking for something like this instead (I have done this other picture with GNUplot):
How can I do it?
You could use cmap.set_bad to define a color for the NaN values:
import numpy as np
import matplotlib.pyplot as plt
from scipy.interpolate import griddata
import matplotlib.colors as colors
from matplotlib import cm
import copy
# Some data
x = np.array([0, 1, 3, 0, 2, 4])
y = np.array([0, 0, 0, 1, 1, 1])
z = np.array([2, 2, 3, 2, 3, 4])
# Interpolation on a grid:
nrb_points = 101
xi = np.linspace(-.5, 4.5, nrb_points)
yi = np.linspace(-.5, 1.5, nrb_points)
XI, YI = np.meshgrid(xi, yi)
xy = np.vstack((x, y)).T
XY = (XI.ravel(), YI.ravel())
ZI = griddata(points, z, XY,
method='linear',
fill_value=np.nan) # Value used [for] points
# outside of the convex hull
# of the input points.
ZI = ZI.reshape(XI.shape)
# Color map:
cmap = copy.copy(cm.jet)
cmap.set_bad('grey', 1.)
# Graph:
plt.pcolormesh(xi, yi, ZI,
#norm=colors.LogNorm(),
cmap=cmap);
plt.colorbar(label='z');
plt.plot(x, y, 'ko');
plt.xlabel('x'); plt.ylabel('y');
the result is:
I would also use griddata instead of RBF method for the interpolation. Then, point outside the input data area (i.e. the convex hull) can be set to NaN.
I want to animate a point moving along a path from one location to another on the map.
For example, I drawn a path from New York to New Delhi, using Geodetic transform. Eg. taken from docs Adding data to the map
plt.plot([ny_lon, delhi_lon], [ny_lat, delhi_lat],
color='blue', linewidth=2, marker='o',
transform=ccrs.Geodetic(),
)
Now i want to move a point along this path.
My idea was to somehow get some (say 50) points, along the path and plot a marker on each point for each frame. But I am not able to find a way to get the points on the path.
I found a function transform_points under classCRS, but I am unable to use this, as this gives me the same number of points i have, not the points in between.
Thanks in advance!
There are a couple of approaches to this.
The matplotlib approach
I'll start with perhaps the most basic if you are familiar with matplotlib, but this approach suffers from indirectly using cartopy's functionality, and is therefore harder to configure/extend.
There is a private _get_transformed_path method on a Line2D object (the thing that is returned from plt.plot). The resulting TransformedPath object has a get_transformed_path_and_affine method, which basically will give us the projected line (in the coordinate system of the Axes being drawn).
In [1]: import cartopy.crs as ccrs
In [3]: import matplotlib.pyplot as plt
In [4]: ax = plt.axes(projection=ccrs.Robinson())
In [6]: ny_lon, ny_lat = -75, 43
In [7]: delhi_lon, delhi_lat = 77.23, 28.61
In [8]: [line] = plt.plot([ny_lon, delhi_lon], [ny_lat, delhi_lat],
...: color='blue', linewidth=2, marker='o',
...: transform=ccrs.Geodetic(),
...: )
In [9]: t_path = line._get_transformed_path()
In [10]: path_in_data_coords, _ = t_path.get_transformed_path_and_affine()
In [11]: path_in_data_coords.vertices
Out[11]:
array([[-6425061.82215208, 4594257.92617961],
[-5808923.84969279, 5250795.00604155],
[-5206753.88613758, 5777772.51828996],
[-4554622.94040482, 6244967.03723341],
[-3887558.58343227, 6627927.97123701],
[-3200922.19194864, 6932398.19937816],
[-2480001.76507805, 7165675.95095855],
[-1702269.5101901 , 7332885.72276795],
[ -859899.12295981, 7431215.78426759],
[ 23837.23431173, 7453455.61302756],
[ 889905.10635756, 7397128.77301289],
[ 1695586.66856764, 7268519.87627204],
[ 2434052.81300274, 7073912.54130764],
[ 3122221.22299409, 6812894.40443648],
[ 3782033.80448001, 6478364.28561403],
[ 4425266.18173684, 6062312.15662039],
[ 5049148.25986903, 5563097.6328901 ],
[ 5616318.74912886, 5008293.21452795],
[ 6213232.98764984, 4307186.23400115],
[ 6720608.93929235, 3584542.06839575],
[ 7034261.06659143, 3059873.62740856]])
We can pull this together with matplotlib's animation functionality to do as requested:
import cartopy.crs as ccrs
import matplotlib.animation as animation
import matplotlib.pyplot as plt
ax = plt.axes(projection=ccrs.Robinson())
ax.stock_img()
ny_lon, ny_lat = -75, 43
delhi_lon, delhi_lat = 77.23, 28.61
[line] = plt.plot([ny_lon, delhi_lon], [ny_lat, delhi_lat],
color='blue', linewidth=2, marker='o',
transform=ccrs.Geodetic(),
)
t_path = line._get_transformed_path()
path_in_data_coords, _ = t_path.get_transformed_path_and_affine()
# Draw the point that we want to animate.
[point] = plt.plot(ny_lon, ny_lat, marker='o', transform=ax.projection)
def animate_point(i):
verts = path_in_data_coords.vertices
i = i % verts.shape[0]
# Set the coordinates of the line to the coordinate of the path.
point.set_data(verts[i, 0], verts[i, 1])
ani = animation.FuncAnimation(
ax.figure, animate_point,
frames= path_in_data_coords.vertices.shape[0],
interval=125, repeat=True)
ani.save('point_ani.gif', writer='imagemagick')
plt.show()
The cartopy approach
Under the hood, cartopy's matplotlib implementation (as used above), is calling the project_geometry method. We may as well make use of this directly as it is often more convenient to be using Shapely geometries than it is matplotlib Paths.
With this approach, we simply define a shapely geometry, and then construct the source and target coordinate reference systems that we want to convert the geometry from/to:
target_cs.project_geometry(geometry, source_cs)
The only thing we have to watch out for is that the result can be a MultiLineString (or more generally, any Multi- geometry type). However, in our simple case, we don't need to deal with that (incidentally, the same was true of the simple Path returned in the first example).
The code to produce a similar plot to above:
import cartopy.crs as ccrs
import matplotlib.animation as animation
import matplotlib.pyplot as plt
import numpy as np
import shapely.geometry as sgeom
ax = plt.axes(projection=ccrs.Robinson())
ax.stock_img()
ny_lon, ny_lat = -75, 43
delhi_lon, delhi_lat = 77.23, 28.61
line = sgeom.LineString([[ny_lon, ny_lat], [delhi_lon, delhi_lat]])
projected_line = ccrs.PlateCarree().project_geometry(line, ccrs.Geodetic())
# We only animate along one of the projected lines.
if isinstance(projected_line, sgeom.MultiLineString):
projected_line = projected_line.geoms[0]
ax.add_geometries(
[projected_line], ccrs.PlateCarree(),
edgecolor='blue', facecolor='none')
[point] = plt.plot(ny_lon, ny_lat, marker='o', transform=ccrs.PlateCarree())
def animate_point(i):
verts = np.array(projected_line.coords)
i = i % verts.shape[0]
# Set the coordinates of the line to the coordinate of the path.
point.set_data(verts[i, 0], verts[i, 1])
ani = animation.FuncAnimation(
ax.figure, animate_point,
frames=len(projected_line.coords),
interval=125, repeat=True)
ani.save('projected_line_ani.gif', writer='imagemagick')
plt.show()
Final remaaaaarrrrrrks....
The approach naturally generalises to animating any type of matplotlib Arrrrtist.... in this case, I took a bit more control over the great circle resolution, and I animated an image along the great circle:
import cartopy.crs as ccrs
import matplotlib.animation as animation
import matplotlib.pyplot as plt
import numpy as np
import shapely.geometry as sgeom
ax = plt.axes(projection=ccrs.Mercator())
ax.stock_img()
line = sgeom.LineString([[-5.9845, 37.3891], [-82.3666, 23.1136]])
# Higher resolution version of Mercator. Same workaround as found in
# https://github.com/SciTools/cartopy/issues/8#issuecomment-326987465.
class HighRes(ax.projection.__class__):
#property
def threshold(self):
return super(HighRes, self).threshold / 100
projected_line = HighRes().project_geometry(line, ccrs.Geodetic())
# We only animate along one of the projected lines.
if isinstance(projected_line, sgeom.MultiLineString):
projected_line = projected_line.geoms[0]
# Add the projected line to the map.
ax.add_geometries(
[projected_line], ax.projection,
edgecolor='blue', facecolor='none')
def ll_to_extent(x, y, ax_size=(4000000, 4000000)):
"""
Return an image extent in centered on the given
point with the given width and height.
"""
return [x - ax_size[0] / 2, x + ax_size[0] / 2,
y - ax_size[1] / 2, y + ax_size[1] / 2]
# Image from https://pixabay.com/en/sailing-ship-boat-sail-pirate-28930/.
pirate = plt.imread('pirates.png')
img = ax.imshow(pirate, extent=ll_to_extent(0, 0), transform=ax.projection, origin='upper')
ax.set_global()
def animate_ship(i):
verts = np.array(projected_line.coords)
i = i % verts.shape[0]
# Set the extent of the image to the coordinate of the path.
img.set_extent(ll_to_extent(verts[i, 0], verts[i, 1]))
ani = animation.FuncAnimation(
ax.figure, animate_ship,
frames=len(projected_line.coords),
interval=125, repeat=False)
ani.save('arrrr.gif', writer='imagemagick')
plt.show()
All code and images for this answer can be found at https://gist.github.com/pelson/618a5f4ca003e56f06d43815b21848f6.
I'm looking for a way to plot filled rectangles on a Basemap. I could easily draw the rectangle's edges using the drawgreatcircle method, but I cannot find a way to actually fill these rectangles (specifying color and alpha).
You can add a matplotlib.patches.Polygon() directly to your axes. The question is whether you want your rectangles defined the plot coordinates (straight lines on the plot) or in map coordinates (great circles on the plot). Either way, you specify vertices in map coordinates and then transform them to plot coordinates by calling the Basemap instance (m() in the below example), build a Polygon yourself, and add it manually to the axes to be rendered.
For rectangles defined in plot coordinates, here's an example:
from mpl_toolkits.basemap import Basemap
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.patches import Polygon
def draw_screen_poly( lats, lons, m):
x, y = m( lons, lats )
xy = zip(x,y)
poly = Polygon( xy, facecolor='red', alpha=0.4 )
plt.gca().add_patch(poly)
lats = [ -30, 30, 30, -30 ]
lons = [ -50, -50, 50, 50 ]
m = Basemap(projection='sinu',lon_0=0)
m.drawcoastlines()
m.drawmapboundary()
draw_screen_poly( lats, lons, m )
plt.show()
For rectangles defined in map coordinates, use the same approach, but interpolate your line in map space before transforming to plot coordinates. For each line segment, you'll have to do:
lats = np.linspace( lat0, lat1, resolution )
lons = np.linspace( lon0, lon1, resolution )
Then transform these map coordinates to plot coordinates (as above, with m()) and again create a Polygon with the plot coordinates.
Using Andrew's answer, I get the error
TypeError: len() of unsized object.
However, casting the zip to a list fixes this.
Complete code:
from mpl_toolkits.basemap import Basemap
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.patches import Polygon
def draw_screen_poly( lats, lons, m):
x, y = m( lons, lats )
xy = zip(x,y)
poly = Polygon( list(xy), facecolor='red', alpha=0.4 )
plt.gca().add_patch(poly)
lats = [ -30, 30, 30, -30 ]
lons = [ -50, -50, 50, 50 ]
m = Basemap(projection='sinu',lon_0=0)
m.drawcoastlines()
m.drawmapboundary()
draw_screen_poly( lats, lons, m )
plt.show()
Similar answer to above, but more basic code:
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
from matplotlib.patches import Polygon
map = Basemap(projection='cyl')
map.drawmapboundary(fill_color='aqua')
map.fillcontinents(color='coral',lake_color='aqua')
map.drawcoastlines()
x1,y1 = map(-25,-25)
x2,y2 = map(-25,25)
x3,y3 = map(25,25)
x4,y4 = map(25,-25)
poly = Polygon([(x1,y1),(x2,y2),(x3,y3),(x4,y4)],facecolor='red',edgecolor='green',linewidth=3)
plt.gca().add_patch(poly)
plt.show()