how can I extract contour lines from data imported through cartopy's feature interface? If the solution involves geoviews.feature or another wrapper, that is OK, of course.
For instance, how would I extract the data plotted as cfeature.COASTLINE in the following example?
import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import cartopy.feature as cfeature
ax = plt.axes(projection=ccrs.PlateCarree())
ax.add_feature(cfeature.COASTLINE)
plt.show()
I'm grateful for any hints you might have!
FWIW, in basemap, I would do it like this:
import mpl_toolkits.basemap as bm
import matplotlib.pyplot as plt
m = bm.Basemap(width=2000e3,height=2000e3,
resolution='l',projection='stere',
lat_ts=70,lat_0=70,lon_0=-60.)
fig,ax=plt.subplots()
coastlines = m.drawcoastlines().get_segments()
You can get the coordinates for the plotted lines directly from the feature, which contains a set of shapely.MultiLineStrings. As a proof of concept, check out this code:
import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import cartopy.feature as cfeature
fig, (ax1,ax2) = plt.subplots(nrows=2, subplot_kw = dict(projection=ccrs.PlateCarree()))
ax1.add_feature(cfeature.COASTLINE)
for geom in cfeature.COASTLINE.geometries():
for g in geom.geoms:
print(list(g.coords))
ax2.plot(*zip(*list(g.coords)))
plt.show()
which gives this picture:
In other words, you can iterate over the MultiLineStrings of the feature by accessing its geometries(). Each of these MultiLineStrings then contains one or more LineStrings, which have a coords attribute that can be converted into a list. Hope this helps.
For future reference: Some time later, I also came across this (more general?) method to access any feature:
import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import cartopy.io.shapereader as shpreader
shpfilename = shpreader.natural_earth(resolution='110m',
category='physical',
name='coastline')
coastlines = shpreader.Reader(shpfilename).records()
fig, ax = plt.subplots(subplot_kw = dict(projection=ccrs.PlateCarree()))
for c in coastlines:
for g in c.geometry:
ax.plot(*zip(*list(g.coords)))
yielding the same plot as above.
Related
I've been working to make a visual for a poster regarding the physical domain that I am studying. I'm working with a nested domain, so I have 1 smaller domain inside a larger outer domain. I'm trying to create a cartopy plot that shows both the outer domain and inner domain. Ideally, the result would look something like this:
I'm really struggling with trying to get my smaller domain inscribed onto my map. I've attempted to make a Shapely LinearRing to show the inner domain, but it is not working. Here's the code I have created so far:
# Imports
import numpy as np
import sys, os
import matplotlib.pyplot as plt
%matplotlib inline
import netCDF4
from netCDF4 import Dataset
from matplotlib.cm import get_cmap
import cartopy.crs as ccrs
import cartopy.feature as cfeature
from cartopy.feature import NaturalEarthFeature, COLORS
import metpy as mp
import metpy.calc as mpcalc
from metpy.calc import divergence, smooth_gaussian
from metpy.units import units
import xarray as xr
from wrf import getvar, interplevel, to_np, latlon_coords, get_cartopy, cartopy_xlim, cartopy_ylim, ALL_TIMES
from shapely.geometry.polygon import LinearRing
from cartopy.mpl.ticker import LongitudeFormatter, LatitudeFormatter
from shapely import geometry
# Get 1km lats/lons
lats1km = getvar(ds1, 'lat')
lons1km = getvar(ds1, 'lon')
lat1km_max = to_np(np.max(lats1km))
lat1km_min = to_np(np.min(lats1km))
lon1km_max = to_np(np.max(lons1km))
lon1km_min = to_np(np.min(lons1km))
# Get 3km lats/lons
lats3km = getvar(ds3, 'lat')
lons3km = getvar(ds3, 'lon')
lat3km_max = to_np(np.max(lats3km))
lat3km_min = to_np(np.min(lats3km))
lon3km_max = to_np(np.max(lons3km))
lon3km_min = to_np(np.min(lons3km))
domain = [lon3km_min, lat3km_min, lon3km_max, lat3km_max]
lons = [lat1km_min, lat1km_min, lat1km_max, lat1km_max]
lats = [lon1km_min, lon1km_max, lon1km_max, lon1km_min]
ring = LinearRing(list(zip(lons, lats)))
geom = geometry.box(minx=lon1km_min, miny=lat1km_min, maxx=lon1km_max, maxy=lat1km_max)
# Grab CRS
crs = get_cartopy(wrfin=ds1)
# Create figure and axes
fig = plt.figure(figsize=(20,10))
ax0 = fig.add_subplot(1, 1, 1, projection=crs)
ax0.set_extent([lon3km_min, lon3km_max, lat3km_min, lat3km_max])
ax0.add_geometries([ring], crs=crs, facecolor='blue', edgecolor='black')
ax0.add_geometries([geom], crs=crs, alpha=0.3)
plot_background(ax0)
This yields my outer domain, but not my inner domain:
What am I doing wrong, and what can I do to get my inner domain shown on the map? Thank you for the help! I really appreciate it!
NOTE: I have already attempted the solution in this link. I am still unable to visualize my polygon.
Have a look at EOmaps ! (I'm the dev) it provides simple functions to add static (or interactive) indicators such as projected rectangles or ellipses to cartopy plots in 1 line!
from eomaps import Maps
m = Maps()
m.add_coastlines()
props = dict(xy=(10, 45), xy_crs=4326, radius_crs=4326, shape="rectangles")
m.add_marker(**props, radius=3, fc=(0,1,0,.5), ec="r", lw=2)
m.add_marker(**props, radius=5, fc="none", ec="k")
m.add_marker(**props, radius=(15, 10), fc="none", ec="m", ls="--", lw=2)
m.figure.ax.set_extent((-15., 65., -5., 75.))
When I run the code below I notice that the heatmap does not have a square shape knowing that I have used square=True but it did not work! Any idea how can I print the heatmap in a square format? Thank you!
The code:
from datetime import datetime
import numpy as np
import pandas as pd
import matplotlib as plt
import os
import seaborn as sns
temp_hourly_A5_A7_AX_ASHRAE=pd.read_csv('C:\\Users\\cvaa4\\Desktop\\projects\\s\\temp_hourly_A5_A7_AX_ASHRAE.csv',index_col=0, parse_dates=True, dayfirst=True, skiprows=2)
sns.heatmap(temp_hourly_A5_A7_AX_ASHRAE,cmap="YlGnBu", vmin=18, vmax=27, square=True, cbar=False, linewidth=0.0001);
The result:
square=True should work to have square cells, below is a working example:
import pandas as pd
import numpy as np
import seaborn as sns
df = pd.DataFrame(np.tile([0,1], 15*15).reshape(-1,15))
sns.heatmap(df, square=True)
If you want a square shape of the plot however, you can use set_aspect and the shape of the data:
ax = sns.heatmap(df)
ax.set_aspect(df.shape[1]/df.shape[0]) # here 0.5 Y/X ratio
You can use matplotlib and set a figsize before plotting heatmap.
import numpy as np
import seaborn as sns
import matplotlib.pyplot as plt
rnd = np.random.default_rng(12345)
data = rnd.uniform(-100, 100, [100, 50])
plt.figure(figsize=(6, 5))
sns.heatmap(data, cmap='viridis');
Note that I used figsize=(6, 5) rather than a square figsize=(5, 5). This is because on a given figsize, seaborn also puts the colorbar, which might cause the heatmap to be squished a bit. You might want to change those figsizes too depending on what you need.
I have a netcdf file ('test.nc'). The variables of the netcdf file are the following:
variables(dimensions): float64 lon(lon), float64 lat(lat), int32 crs(), int16 Band1(lat,lon)
I am interested in the ´Band1´ variable.
Using cartopy, I could plot the data using the following code:
import numpy as np
import pandas as pd
import gzip
from netCDF4 import Dataset,num2date
import time
import matplotlib.pyplot as plt
import os
import matplotlib as mplt
#mplt.use('Agg')
import cartopy.crs as ccrs
import cartopy.feature as cfea
import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1 import make_axes_locatable
projection=ccrs.PlateCarree()
bbox=[-180,180,-60,85];creg='glob'
mplt.rc('xtick', labelsize=9)
mplt.rc('ytick', labelsize=9)
nc = Dataset('test.nc','r')
lat = nc.variables['lat'][:]
lon = nc.variables['lon'][:]
kopi= (nc.variables['Band1'][:,:])
nc.close()
fig=plt.figure(figsize=(11,5))
ax=fig.add_subplot(1,1,1,projection=projection)
ax.set_extent(bbox,projection)
ax.add_feature(cfea.COASTLINE,lw=.5)
ax.add_feature(cfea.RIVERS,lw=.5)
ax.add_feature(cfea.BORDERS, linewidth=0.6, edgecolor='dimgray')
ax.background_patch.set_facecolor('.9')
levels=[1,4,8,11,14,17,21,25,29]
cmap=plt.cm.BrBG
norm=mplt.colors.BoundaryNorm(levels,cmap.N)
ddlalo=.25
pc=ax.contourf(lon,lat,kopi,levels=levels,transform=projection,cmap=cmap,norm=norm,extend='both')
divider = make_axes_locatable(ax)
ax_cb = divider.new_horizontal(size="3%", pad=0.1, axes_class=plt.Axes)
fig.colorbar(pc,extend='both', cax=ax_cb)
fig.add_axes(ax_cb)
fig.colorbar(pc,extend='both', cax=ax_cb)
ttitle='Jony'
ax.set_title(ttitle,loc='left',fontsize=9)
plt.show()
However, I would like just to plot a selection of values inside the variable ´Band1´. I thought I could use the following code:
kopi= (nc.variables['Band1'][:,:])<=3
However it does not work and instead of plotting the area corresponding to the value selection it selected the all map.
How could I select and plot a desired range of values inside the variables ´Band1´?
Just mask the values with np.nan
kopi[kopi <=3] = np.nan
This should yield to white pixels in your plot.
Please provide test data in the future.
Original(2018.11.01)
I have 3 numpy：x、y、z,created by my laser scanner(40 degree / 1 step).
I want to used them to build a 3D model.
I think it must should be use matplotlib.tri
But I have no idea to decide triangulated data
Here is my data ：https://www.dropbox.com/s/d9p62kv9jcq9bwh/xyz.zip?dl=0
And Original model：https://i.imgur.com/XSyONff.jpg
Code：
import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.tri as mtri
x_all=np.load("x.npy")
y_all=np.load("y.npy")
z_all=np.load("z.npy")
tri = #I have no idea...
fig = plt.figure()
ax = fig.gca(projection='3d')
ax.plot_trisurf(x_all,y_all,z_all,triangles=tri.triangles)
Thank so much.
Update(2018.11.02)
I try this way to decide triangulated data
Delaunay Triangulation of points from 2D surface in 3D with python?
code:
import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.tri as mtri
from stl import mesh
x_all=np.load("x.npy")
y_all=np.load("y.npy")
z_all=np.load("z.npy")
model=np.vstack((x_all,y_all,z_all))
model=np.transpose(model)
model -= model.mean(axis=0)
rad = np.linalg.norm(model, axis=1)
zen = np.arccos(model[:,-1] / rad)
azi = np.arctan2(model[:,1], model[:,0])
tris = mtri.Triangulation(zen, azi)
plt.show()
And my model looks like:
https://i.stack.imgur.com/KVPHP.png
https://i.stack.imgur.com/LLQsQ.png
https://i.stack.imgur.com/HdzFm.png
Even though it has better surface on it,but there is a big hole over my model.Any idea to fixs it?
Assuming you want to reduce the complexity, i.e find triangles in your files to reduce the complexity. You may look into fitting a convex hull to your points, see here fore more info
Based on the file you provided this produces a surf plot of the object.
from numpy import load, stack
from matplotlib.pyplot import subplots
from mpl_toolkits.mplot3d import Axes3D
from scipy import spatial
x = load("x.npy")
y = load("y.npy")
z = load("z.npy")
points = stack((x,y,z), axis = -1)
v = spatial.ConvexHull(points)
fig, ax = subplots(subplot_kw = dict(projection = '3d'))
ax.plot_trisurf(*v.points.T, triangles = v.simplices.T)
fig.show()
I am building a seaborn graphics with this code :
import matplotlib.pyplot as plt
import pandas as pd
import seaborn as sns
%matplotlib inline
df=pd.DataFrame(data=['a','b','c','d','a','a','b','c','a','a'],columns['datos'])
tabla=df['datos'].value_counts().reset_index()
fig, ax1 = plt.subplots(figsize=(6,4))
sns.set()
sns.barplot(x='index', y='datos', data=tabla, ax=ax1)
It does work properly....but How could I get the code of the colors used for every bar?
I have tried with :
f.get_color()
ax.get_color()
but no success at all...
thanks in advance
waly
I admit it's an ugly way, but you will need to access the children of your plot. Note that this probably won't work if you plot more than just the countplot, since you will get all used Rectangle colors in your plot.
import matplotlib.pyplot as plt
from matplotlib.patches import Rectangle
import pandas as pd
import seaborn as sns
%matplotlib inline
sns.set()
df=pd.DataFrame(data=['a','b','c','d','a','a','b','c','a','a'],columns=['datos'])
tabla=df['datos'].value_counts().reset_index()
fig, ax1 = plt.subplots(figsize=(6,4))
sns.barplot(x='index', y='datos', data=tabla, ax=ax1)
bars = [r for r in ax1.get_children() if type(r)==Rectangle]
colors = [c.get_facecolor() for c in bars[:-1]] # I think the last Rectangle is the background.