Develop Reference

matplotlib custom path markers not displaying correctly

just wondering if anybody has experience with matplotlib custom markers
I want each marker in my plot to be a pie chart. To achieve this, my strategy was to create custom markers using the path class, method wedge.
https://matplotlib.org/stable/api/path_api.html
However is not displaying correctly, in particular with wedges defined with angles in the left quadrants. However, the path defined by the wedge class method seems to be correct and wedges are displayed correctly if using PathPatch and .add_patch()
See example below
import numpy as np
import math
import matplotlib.path as mpath
import matplotlib.cm
import matplotlib.pyplot as plt
import matplotlib.patches as patches
#Create wedges from angles
angles = np.array( [0,140,160,360] ) #Wedges angles
wedges=[]
for i in range(len(angles)-1):
angle0= angles[i]
angle1= angles[i+1]
dangle = angle1-angle0
wedge0=None
if dangle>0:
wedge0= mpath.Path.wedge(angle0, angle1)
wedge0= mpath.Path.wedge(angle0, angle1)
wedges.append(wedge0)
fig = plt.figure(figsize=(10,5))
ax1 = fig.add_subplot(121)
ax1.set_xlim(-1, 1)
ax1.set_ylim(-1, 1)
ax2 = fig.add_subplot(122)
ax2.set_xlim(-2, 2)
ax2.set_ylim(-2, 2)
tab10 = matplotlib.cm.get_cmap('tab10')
for i, w0 in enumerate(wedges):
ax1.scatter(0,0, marker=w0, c = [tab10(i)], s=20000) #Use path markers
patch = patches.PathPatch(w0, color=tab10(i)) #Use patch
ax2.add_patch(patch)
plt.show()
Notice that the wedge on the left plot is sticking out, which is not supposed to.
Is this a bug in the matplotlib markers' code?

I managed to get the pie charts to display correctly.
Scaling by doing affine transforms does not help because the path markaers are all resized, as in
line 495 of markers.py .
def _set_custom_marker(self, path):
rescale = np.max(np.abs(path.vertices)) # max of x's and y's.
self._transform = Affine2D().scale(0.5 / rescale)
self._path = path
My solution is to modify the vertices in the created wedges by inserting new vertices that define a bounding box, slightly larger than the circle with radius 1.
Here is the modified code
import numpy as np
import matplotlib.path as mpath
import matplotlib.cm
import matplotlib.pyplot as plt
import matplotlib.patches as patches
def getBoundedWedge(angle0, angle1):
wedge0= mpath.Path.wedge(angle0, angle1)
#print(f"wedge0:{wedge0}")
vertices = wedge0.vertices
codes = wedge0.codes
#Add ghost vertices to define bounding box
vertices= np.insert( vertices, 0, [[1.1,1.1], [-1.1,1.1] , [-1.1,-1.1], [1.1,-1.1]] , axis=0)
codes = np.insert( codes, 0, [1,1,1,1])
wedgeextra = mpath.Path(vertices, codes)
return wedgeextra
#Create wedges from angles
angles = np.array( [0,140,160,360] ) #Wedges angles
wedges=[]
for i in range(len(angles)-1):
angle0= angles[i]
angle1= angles[i+1]
dangle = angle1-angle0
wedge0=None
if dangle>0:
wedge0= getBoundedWedge(angle0, angle1)
wedges.append(wedge0)
fig = plt.figure(figsize=(10,5))
ax1 = fig.add_subplot(121)
ax1.set_xlim(-1, 1)
ax1.set_ylim(-1, 1)
ax2 = fig.add_subplot(122)
ax2.set_xlim(-2, 2)
ax2.set_ylim(-2, 2)
tab10 = matplotlib.cm.get_cmap('tab10')
for i, w0 in enumerate(wedges):
ax1.scatter(0,0, marker=w0, c = [tab10(i)], s=20000) #Use path markers
patch = patches.PathPatch(w0, color=tab10(i)) #Use patch
ax2.add_patch(patch)
plt.show()
And the output is as follows

Plot dual points with one point fixed

I'm trying to plot a set of points with a special feature,
first plot 2 points with a random coordinates x and y, in a range from 0 to 200,
but my problem is how can set this points as fixed or centers, take this center-points and from this points, plot one new point with random coordinates(as pairs of points A-a, B-b, etc), and define the distance that can't be higher than 30 meter or units of distance beetwen this points. To get the points like this
I add part of my code to make this
import matplotlib as mpl
from matplotlib.figure import Figure
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.patches as mpatches
from itertools import product
from matplotlib.lines import Line2D
fig,ax=plt.subplots()
#AP POINTS
###################################################
points_xA=np.random.randint(0,200)
points_yA=np.random.randint(0,200)
points_xB=np.random.randint(0,200)
points_yB=np.random.randint(0,200)
center1=np.array([points_xA,points_yB])
center2=np.array([points_xB,points_yB])
ax.annotate("A",xy=(center1),fontsize=12,bbox={"boxstyle":"circle","color":"orange"})
ax.annotate("B",xy=(center2),fontsize=12,bbox={"boxstyle":"circle","color":"orange"})
#STA POINTS
######################################################
#points_xa=np.random.randint()
#points_ya=np.random.randint()
#points_xb=np.random.randint()
#points_yb=np.random.randint()
######################################################
#LABELS
plt.title('random points')
plt.xlabel('x(m)')
plt.ylabel('y(m)')
plt.xlim(0,210)
plt.ylim(0,210)
plt.grid(True)
plt.show()

i have develop a script that plot points as i wanted, but it have some issues:
1.- The menu or bar where the zoom functions, save image, etc. It disappeared and I can't zoom, which I think would be the most important thing.
2.- The table where is the coordinates of each point, for example, for AP_A it have his STA_A1 o more, depending how many STA's you want( for 3 STA's it would be STA_A1, STA_A2, STA_A3, etc)
but in the table apears as STA_A1, for any STA, in the next image it's more clear
I hope it will be useful to someone, on the other hand if someone can correct those errors in my code it would be great, I thank to this community where I have found some solutions on several occasions.
code:
import matplotlib as mpl
from matplotlib.figure import Figure
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.patches as mpatches
from itertools import product
from matplotlib.lines import Line2D
##########################
#RADIOS
radius1=30
#radius2=30
#AP POINTS
###################################################
def setNodos(n,rango=300,n_clientes=6):
listaNodos = []
for i in range(n):
points_x=np.random.randint(0,rango)
points_y=np.random.randint(0,rango)
listaNodos.append((np.array([points_x,points_y]),n_clientes))
return listaNodos
listaNodos = setNodos(4,300,3)
abc = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
points_x = []
points_y = []
sta_cant = []
points_sta_x = []
points_sta_y = []
sta_names = []
for nodo,n in listaNodos:
points_x.append(nodo[0])
points_y.append(nodo[1])
sta_cant.append(n)
t_data=[]
########################################
fig = plt.figure(figsize = (15,10))
ax = plt.subplot2grid((3,2), (0, 0),colspan=2,rowspan=2)
l=0
sta_n=0
print(listaNodos)
for centerA,sta_n in listaNodos:
cxA,cyA = centerA
ax.annotate(abc[l],xy=(centerA),fontsize=12,bbox={"boxstyle":"circle","color":"orange"})
#RADIO CIRCULO ROJO
ct1A=np.linspace(0,2*np.pi)
circx11,circy12 = radius1*np.cos(ct1A)+cxA, radius1*np.sin(ct1A)+cyA
plt.plot(circx11, circy12, ls="-",color='red')
#RELLENO CIRCULO ROJO
ax= plt.gca()
t1= plt.Polygon([[i,j] for i, j in zip(circx11,circy12)], color='slategrey', alpha=0.2)
ax.add_patch(t1)
######################################################
#STA POINTS
######################################################
r_sta = np.random.randint(0,radius1,size=sta_n)
tita_sta = np.random.randint(0,359,size=sta_n)
x_sta = np.round(r_sta*np.cos(tita_sta)+cxA,0)
y_sta = np.round(r_sta*np.sin(tita_sta)+cyA,0)
print(x_sta,y_sta)
for x,y in zip(x_sta,y_sta):
#plt.scatter(x,y,c='b',zorder=1000)
x = np.min((300,np.max((0,int(x)))))
y = np.min((300,np.max((0,int(y)))))
ax.annotate(abc[l].lower(),xy=((x,y)),fontsize=10,color='black',
bbox={"boxstyle":"circle","color":"steelblue","alpha":0.5},
)
sta_names.append('STA_%s%i'%(abc[l],l+1))
points_sta_x.append(x)
points_sta_y.append(y)
l+=1
######################################################
#Tabla con coordenadas
plt.xlabel('x(m)')
plt.ylabel('y(m)')
plt.xlim(-10,310)
plt.ylim(-10,310)
ax.grid(True)
plt.title('random points')
t_data.append(points_x+points_sta_x)
t_data.append(points_y+points_sta_y)
print(t_data)
print(sta_n)
collLabels =[('AP_%s'%i) for i in abc[:len(points_x)]]
for name in sta_names:
collLabels.append(name)
print(collLabels)
ax1 = plt.subplot2grid((3,2), (2, 0),colspan=2,rowspan=1)
table=ax1.table(cellText = t_data,
colLabels=collLabels,
rowLabels=('coord_x','coord_y'),
bbox=[0,0.3,0.1+0.05*len(collLabels),0.6+0.01*len(collLabels)]
,cellLoc='center',fontsize=30)
plt.xticks([])
plt.yticks([])
plt.axis('OFF')
plt.tight_layout(rect=[0.01, 0.01, 1.0, 1.0])
#######################################################
#LABELS
ax.set_aspect('equal')
plt.savefig('./salida/escen_random.png')
plt.show()

Dynamic Visualisation of Global Plots

I have produced 17 global plots that show the decadal averages in maximum surface ozone from 1850-2015. Rather than plotting them individually, I wish to create an animation that cycles through them (almost like a gif), i.e. have the same coastlines, axes and colour bar throughout but change what is being plotted as the contour.
Any help on how to adapt my code to do this would be greatly appreciated - thank you in advance!!
import numpy as np
import netCDF4 as n4
import matplotlib.pyplot as plt
from matplotlib import colorbar, colors
import matplotlib.cm as cm
import cartopy as cart
import cartopy.crs as ccrs
from cartopy.mpl.gridliner import LONGITUDE_FORMATTER, LATITUDE_FORMATTER
import cartopy.feature as cfeature
nc = n4.Dataset('datafile.nc','r')
# daily maximum O3 VMR (units: mol mol-1)
sfo3max = nc.variables['sfo3max']
lon = nc.variables['lon'] # longitude
lat = nc.variables['lat'] # latitude
# (I manipulate the data to produce 17 arrays containing the decadal average O3 VMR which are
# listed below in sfo3max_avg)
sfo3max_avg = [sfo3max_1850_1860_avg, sfo3max_1860_1870_avg, sfo3max_1870_1880_avg,
sfo3max_1880_1890_avg, sfo3max_1890_1900_avg, sfo3max_1900_1910_avg,
sfo3max_1910_1920_avg, sfo3max_1920_1930_avg, sfo3max_1930_1940_avg,
sfo3max_1940_1950_avg, sfo3max_1950_1960_avg, sfo3max_1960_1970_avg,
sfo3max_1970_1980_avg, sfo3max_1980_1990_avg, sfo3max_1990_2000_avg,
sfo3max_2000_2010_avg, sfo3max_2010_2015_avg]
# find overall min & max values for colour bar in plots
min_sfo3max_avg = np.array([])
for i in sfo3max_avg:
sfo3max_avg_min = np.amin(i)
min_sfo3max_avg = np.append(min_sfo3max_avg, sfo3max_avg_min)
overall_min_sfo3max_avg = np.amin(min_sfo3max_avg)
max_sfo3max_avg = np.array([])
for i in sfo3max_avg:
sfo3max_avg_max = np.amax(i)
max_sfo3max_avg = np.append(max_sfo3max_avg, sfo3max_avg_max)
overall_max_sfo3max_avg = np.amax(max_sfo3max_avg)
# finally plot the 17 global plots of sfo3max_avg
for k in sfo3max_avg:
fig = plt.figure()
ax = plt.axes(projection=ccrs.PlateCarree())
ax.coastlines() # Adding coastlines
cs = ax.contourf(lon[:], lat[:], k[:], cmap='magma')
ax.set_title('Decadal Average of Maximum O3 Volume Mixing Ratio')
m = plt.cm.ScalarMappable(cmap=cm.magma)
m.set_array(i[:])
m.set_clim(overall_min_sfo3max_avg, overall_max_sfo3max_avg)
# Additional necessary information
cbar = plt.colorbar(m, boundaries=np.arange(overall_min_sfo3max_avg, overall_max_sfo3max_avg
+ 0.5e-08, 0.5e-08))
cbar.set_label('mol mol-1')
# Adding axis labels - latitude & longitude
gridl = ax.gridlines(color="black", linestyle="dotted", draw_labels=True)
gridl.xformatter=LONGITUDE_FORMATTER
gridl.yformatter=LATITUDE_FORMATTER
gridl.xlabels_top = False
gridl.ylabels_right = False
fig.set_size_inches(w=20,h=10)
plt.show() # show global plot

Several elements in your plotting can be kept out of the loop because they only need to be set up once. After you set up the plot elements you can update the plot and animate by looping over the list. This can be achieved by making use of matplotlib's interactive mode as shown in the code below:
import numpy as np
import netCDF4 as n4
import matplotlib
matplotlib.use("nbagg")
import matplotlib.pyplot as plt
from matplotlib import colorbar, colors
import matplotlib.cm as cm
import cartopy as cart
import cartopy.crs as ccrs
from cartopy.mpl.gridliner import LONGITUDE_FORMATTER, LATITUDE_FORMATTER
import cartopy.feature as cfeature
nc = n4.Dataset('datafile.nc','r')
# daily maximum O3 VMR (units: mol mol-1)
sfo3max = nc.variables['sfo3max']
lon = nc.variables['lon'] # longitude
lat = nc.variables['lat'] # latitude
# (I manipulate the data to produce 17 arrays containing the decadal average O3 VMR which are
# listed below in sfo3max_avg)
sfo3max_avg = [sfo3max_1850_1860_avg, sfo3max_1860_1870_avg, sfo3max_1870_1880_avg,
sfo3max_1880_1890_avg, sfo3max_1890_1900_avg, sfo3max_1900_1910_avg,
sfo3max_1910_1920_avg, sfo3max_1920_1930_avg, sfo3max_1930_1940_avg,
sfo3max_1940_1950_avg, sfo3max_1950_1960_avg, sfo3max_1960_1970_avg,
sfo3max_1970_1980_avg, sfo3max_1980_1990_avg, sfo3max_1990_2000_avg,
sfo3max_2000_2010_avg, sfo3max_2010_2015_avg]
# find overall min & max values for colour bar in plots
min_sfo3max_avg = np.array([])
for i in sfo3max_avg:
sfo3max_avg_min = np.amin(i)
min_sfo3max_avg = np.append(min_sfo3max_avg, sfo3max_avg_min)
overall_min_sfo3max_avg = np.amin(min_sfo3max_avg)
max_sfo3max_avg = np.array([])
for i in sfo3max_avg:
sfo3max_avg_max = np.amax(i)
max_sfo3max_avg = np.append(max_sfo3max_avg, sfo3max_avg_max)
overall_max_sfo3max_avg = np.amax(max_sfo3max_avg)
#setup the plot elements
fig = plt.figure()
fig.set_size_inches(w=20,h=10)
ax = plt.axes(projection=ccrs.PlateCarree())
ax.coastlines() # Adding coastlines
ax.set_title('Decadal Average of Maximum O3 Volume Mixing Ratio')
m = plt.cm.ScalarMappable(cmap=cm.magma)
m.set_array(i[:])
m.set_clim(overall_min_sfo3max_avg, overall_max_sfo3max_avg)
# Additional necessary information
cbar = plt.colorbar(m, boundaries=np.arange(overall_min_sfo3max_avg, overall_max_sfo3max_avg
+ 0.5e-08, 0.5e-08))
cbar.set_label('mol mol-1')
# plot here only the 1st item in your sfo3max_avg list.
cs = ax.contourf(lon[:], lat[:], sfo3max_avg[0][:], cmap='magma')
# Adding axis labels - latitude & longitude
gridl = ax.gridlines(color="black", linestyle="dotted", draw_labels=True)
gridl.xformatter=LONGITUDE_FORMATTER
gridl.yformatter=LATITUDE_FORMATTER
gridl.xlabels_top = False
gridl.ylabels_right = False
plt.ion() # set interactive mode
plt.show()
# finally plot the 17 global plots of sfo3max_avg
for k in sfo3max_avg:
cs = ax.contourf(lon[:], lat[:], k[:], cmap='magma')
plt.gcf().canvas.draw()
plt.pause(1) #control the interval between successive displays, currently set to 1 sec.

Plotting a masked Antarctica with a shapefile or geopandas

I'm trying to plot data around the Antarctica while masking the continent. While I'm using basemap and it has an option to easily mask continents using map.fillcontinents(), the continent considered by basemap includes the ice shelves, which I do not want to mask.
I tried using geopandas from a code I found on the Internet. This works, except the coastline produces an undesired line in what I assume is the beginning/end of the polygon for the Antarctica:
import numpy as np
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
from matplotlib.collections import PatchCollection
import geopandas as gpd
import shapely
from descartes import PolygonPatch
lats = np.arange(-90,-59,1)
lons = np.arange(0,361,1)
X, Y = np.meshgrid(lons, lats)
data = np.random.rand(len(lats),len(lons))
world = gpd.read_file(gpd.datasets.get_path('naturalearth_lowres'))
fig=plt.figure(dpi=150)
ax = fig.add_subplot(111)
m = Basemap(projection='spstere',boundinglat=-60,lon_0=180,resolution='i',round=True)
xi, yi = m(X,Y)
cf = m.contourf(xi,yi,data)
patches = []
selection = world[world.name == 'Antarctica']
for poly in selection.geometry:
if poly.geom_type == 'Polygon':
mpoly = shapely.ops.transform(m, poly)
patches.append(PolygonPatch(mpoly))
elif poly.geom_type == 'MultiPolygon':
for subpoly in poly:
mpoly = shapely.ops.transform(m, poly)
patches.append(PolygonPatch(mpoly))
else:
print(poly, 'blah')
ax.add_collection(PatchCollection(patches, match_original=True,color='w',edgecolor='k'))
The same line appears when I try to use other shapefiles, such as the land one that is available to download for free from Natural Earth Data. So I edited this shapefile in QGIS to remove the borders of the Antarctica. The problem now is that I don't know how to mask everything that's inside the shapefile (and couldn't find how to do it either). I also tried combining the previous code with geopandas by setting the linewidth=0, and adding on top the shapefile I created. The problem is that they are not exactly the same:
Any suggestion on how to mask using a shapefile, or with geopandas but without the line?
Edit: Using Thomas Khün's previous answer with my edited shapefile produces a well masked Antarctica/continents, but the coastline goes outside the round edges of the map:
I uploaded here the edited shapefile I used, but it's the Natural Earth Data 50m land shapefile without the line.

Here an example of how to achieve what you want. I basically followed the Basemap example how to deal with shapefiles and added a bit of shapely magic to restrict the outlines to the map boundaries. Note that I first tried to extract the map outline from ax.patches, but that somehow didn't work, so I defined a circle which has a radius of boundinglat and transformed it using the Basemap coordinate transformation functionality.
import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap
from matplotlib.collections import PatchCollection
from matplotlib.patches import Polygon
import shapely
from shapely.geometry import Polygon as sPolygon
boundinglat = -40
lats = np.arange(-90,boundinglat+1,1)
lons = np.arange(0,361,1)
X, Y = np.meshgrid(lons, lats)
data = np.random.rand(len(lats),len(lons))
fig, ax = plt.subplots(nrows=1, ncols=1, dpi=150)
m = Basemap(
ax = ax,
projection='spstere',boundinglat=boundinglat,lon_0=180,
resolution='i',round=True
)
xi, yi = m(X,Y)
cf = m.contourf(xi,yi,data)
#adjust the path to the shapefile here:
result = m.readshapefile(
'shapefiles/AntarcticaWGS84_contorno', 'antarctica',
zorder = 10, color = 'k', drawbounds = False)
#defining the outline of the map as shapely Polygon:
rim = [np.linspace(0,360,100),np.ones(100)*boundinglat,]
outline = sPolygon(np.asarray(m(rim[0],rim[1])).T)
#following Basemap tutorial for shapefiles
patches = []
for info, shape in zip(m.antarctica_info, m.antarctica):
#instead of a matplotlib Polygon, create first a shapely Polygon
poly = sPolygon(shape)
#check if the Polygon, or parts of it are inside the map:
if poly.intersects(outline):
#if yes, cut and insert
intersect = poly.intersection(outline)
verts = np.array(intersect.exterior.coords.xy)
patches.append(Polygon(verts.T, True))
ax.add_collection(PatchCollection(
patches, facecolor= 'w', edgecolor='k', linewidths=1., zorder=2
))
plt.show()
The result looks like this:
Hope this helps.

For anyone still trying to figure out a simple way to mask a grid from a shapefile, here is a gallery example from the python package Antarctic-Plots which makes this simple.
from antarctic_plots import maps, fetch, utils
import pyogrio
# fetch a grid and shapefile
grid = fetch.bedmachine(layer='surface')
shape = fetch.groundingline()
# subset the grounding line from the coastline
gdf = pyogrio.read_dataframe(shape)
groundingline = gdf[gdf.Id_text == "Grounded ice or land"]
# plot the grid
fig = maps.plot_grd(grid)
# plot the shapefile
fig.plot(groundingline, pen='1p,red')
fig.show()
# mask the inside region
masked_inside = utils.mask_from_shp(
shapefile=groundingline, xr_grid=grid, masked=True)
masked_inside.plot()
# mask the outside region
masked_outside = utils.mask_from_shp(
shapefile=groundingline, xr_grid=grid, masked=True, invert=False)
masked_outside.plot()

Matplotlib Basemap Coastal Coordinates

Is there a way to query basemap to extract all coastal coordinates?
Say user provides lat/lng and the function returns true/false if the coordinates are within 1km from the coast?

The best way to get the coordinates from drawcoastlines() is using its class attribute get_segments(). There is an example how you can get the distance from coast for a single point with longitude ans latitude in decimal degrees. You can adapt this function to use a unique map to calculate all points in a list. I hope it's help you.
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
import numpy as np
def distance_from_coast(lon,lat,resolution='l',degree_in_km=111.12):
plt.ioff()
m = Basemap(projection='robin',lon_0=0,resolution=resolution)
coast = m.drawcoastlines()
coordinates = np.vstack(coast.get_segments())
lons,lats = m(coordinates[:,0],coordinates[:,1],inverse=True)
dists = np.sqrt((lons-lon)**2+(lats-lat)**2)
if np.min(dists)*degree_in_km<1:
return True
else:
return False
Another way to get it:
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
import numpy as np
import os
def save_coastal_data(path,resolution='f'):
m = Basemap(projection='robin',lon_0=0,resolution=resolution)
coast = m.drawcoastlines()
coordinates = np.vstack(coast.get_segments())
lons,lats = m(coordinates[:,0],coordinates[:,1],inverse=True)
D = {'lons':lons,'lats':lats}
np.save(os.path.join(path,'coastal_basemap_data.npy'),D)
def distance_from_coast(lon,lat,fpath,degree_in_km=111.12):
D = np.load(fpath).tolist()
lons,lats = D['lons'],D['lats']
dists = np.sqrt((lons-lon)**2+(lats-lat)**2)
print np.min(dists)*degree_in_km
#Define path
path = 'path/to/directory'
#Run just one time to save the data. Will cost less time
save_coastal_data(path,resolution='h')
distance_from_coast(-117.2547,32.8049,
os.path.join(path,'coastal_basemap_data.npy'))
I've got 0.7 Km.

This is another possibilities that doesn't rely on the basemap projection and gives raw lon/lat coordinates. An advantage/disadvantage is, that the continent lines are not split at the map boundaries.
import matplotlib.pyplot as plt
from mpl_toolkits import basemap
import numpy as np
import os
def get_coastlines(npts_min=0):
# open data and meta data files
dirname_basemap = os.path.dirname(basemap.__file__)
path_points = os.path.join(dirname_basemap, 'data', 'gshhs_c.dat')
path_meta = os.path.join(dirname_basemap, 'data', 'gshhsmeta_c.dat')
# read points for each segment that is specified in meta_file
points_file = open(path_points, 'rb')
meta_file = open(path_meta,'r')
segments = []
for line in meta_file:
# kind=1 are continents, kind=2 are lakes
kind, area, npts, lim_south, lim_north, startbyte, numbytes,\
date_line_crossing = line.split()
points_file.seek(int(startbyte))
data = np.fromfile(points_file, '<f4', count = int(numbytes)/4)
data = data.reshape(int(npts), 2)
if npts_min < int(npts):
segments.append(data)
return segments
def main():
segments = get_coastlines()
fig, ax = plt.subplots(1, 1)
for seg in segments:
plt.plot(seg[:, 0], seg[:, 1])
plt.show()
if __name__ == "__main__":
main()