I have a dataframe in Python containing zipcodes (4 digits), pologyons, and would like to create maps with colored zipcodes based on a column value. I tried this with the geopandas and folium packages but it seems to be not working.
The shapefigures I downloaded from this website https://www.cbs.nl/nl-nl/dossier/nederland-regionaal/geografische-data/gegevens-per-postcode .
The shapefile seems to work when I use this code:
file_path = r'C:\xxxx\CBS_pc4_2020_v1.shp'
gdf_zipcodes = gpd.read_file(file_path)
fig, ax = plt.subplots(figsize=(8,8))
gdf_zipcodes.plot(ax=ax, facecolor='none', edgecolor='gray')
plt.show()
Currently, this is (part of) my dataframe
zipcodes =
Zipcode
Var
Location
Allocation
9941
o
Polygon
7023
7023
o
Polygon
7023
6321
o
Multipolygon
4020
I also have a location dataframe containing zipcodes and specific lon & latitudes like this:
loc_df =
Zipcode
lat
lon
9941
xxx
yyy
7231
xxx
yyy
What does work is creating a map with these specific coordinates, this is the code I used:
map = folium.Map(location =[loc_df['lat'].mean(),loc_df['lon'].mean()], zoom_start=12)
step = cm.StepColormap(colors, vmin = 0, vmax = 9999, index = [], caption = 'step')
color_pallete = sns.color_palette()
color_pallete = sns.color_palette("Set2", 99999)
color_pallete = color_pallete.as_hex()
for index, row in results_1.iterrows():
if row['Var'] == 'o':
folium.Marker([row['lat'], row['lon']], popup = row['Variable Name']).add_to(map)
if row['Var'] == 'x':
c = color_pallete[int(row['Allocation'])]
folium.CircleMarker([row['lat'], row['lon']],radius=5, color = c).add_to(map)
else:
continue
folium.CircleMarker(
location=[row['lon'], row['lat']],
radius=12,
weight=2,
fill=True,
fill_color=colors[int(row['cluster'])],
color=colors[int(row['cluster'])]
).add_to(map)
map.save('map1.html')
Then, I thought this code would work to use the pologyons instead of specific lat and lon values to create the map but unfortunately it does not:
for _, r in zipcodes.iterrows():
# Without simplifying the representation of each borough,
# the map might not be displayed
sim_geo = gpd.GeoSeries(r['geometry']).simplify(tolerance=0.001)
geo_j = sim_geo.to_json()
geo_j = folium.GeoJson(data=geo_j,
style_function=lambda x: {'fillColor': 'blue'})
folium.Popup(r['Location']).add_to(geo_j)
geo_j.add_to(map)
In the end I would like to color based on the allocation of the dataframe and create markers such as in the first folium map but for now I would really like to visualize the polygons (and hopefully I can find out how I create the colors after that).
I have a DataFrame as below, I want to convert data to a multi polygon DataFrame, because I want to plot each multi polygon on a map.
I know how to convert if I have two data point, but with 6 data point, I don't know how to convert it. can anyone help me please.
geometry = [Point(xy) for xy in zip(neightrip_counts_.lan0, neightrip_counts_.long0)]
geometry
#neightrip_counts_.lan1, neightrip_counts_.long1,neightrip_counts_.lan2, neightrip_counts_.long2
lan0 long0 lan1 long1 lan2 long2
0 59.915667 10.777567 59.916738 10.779916 59.914943 10.773977
1 59.929853 10.711515 59.929435 10.713682 59.927596 10.710033
2 59.939230 10.759170 59.937205 10.760581 59.943750 10.760306
3 59.912520 10.762240 59.911594 10.761774 59.912347 10.763815
4 59.929634 10.732839 59.927140 10.730981 59.931081 10.736003
Let me rename the dataframe neightrip_counts_ as df for brevity. Here is the relevant code that will create a polygon for each row of dataframe.
df['geometry'] = [Polygon([(z[0],z[1]), (z[2],z[3]), (z[4],z[5])]) for z in zip(df.long0, df.lan0, df.long1, df.lan1, df.long2, df.lan2)]
gpdf = df.set_geometry("geometry", drop=True)
gpdf.plot()
By the way, you must be careful about the sequence of (long, lat).
start_coords = [ gdf.centroid[0].x, gdf.centroid[0].y] # is wrong
Use this in stead.
start_coords = [ gdf.centroid[0].y, gdf.centroid[0].x]
Edit
For the benefits of the readers, here is the complete runnable code:
import pandas as pd
import geopandas as gpd
from io import StringIO
from shapely.geometry import Polygon, Point, LineString
import numpy as np
import folium
data1 = """index lan0 long0 lan1 long1 lan2 long2
0 59.915667 10.777567 59.916738 10.779916 59.914943 10.773977
1 59.929853 10.711515 59.929435 10.713682 59.927596 10.710033
2 59.939230 10.759170 59.937205 10.760581 59.943750 10.760306
3 59.912520 10.762240 59.911594 10.761774 59.912347 10.763815
4 59.929634 10.732839 59.927140 10.730981 59.931081 10.736003"""
# read/parse data into dataframe
df0 = pd.read_csv(StringIO(data1), sep='\s+', index_col='index')
# create `geometry` column
df0['geometry'] = [Polygon([(xy[0],xy[1]), (xy[2],xy[3]), (xy[4],xy[5])]) \
for xy in zip(df0.long0, df0.lan0, df0.long1, df0.lan1, df0.long2, df0.lan2)]
# set geometry
gpdf = df0.set_geometry("geometry", drop=True)
# do check plot. (uncomment next line)
#gpdf.plot()
# make geojson
center_pt = gpdf.centroid[0].y, gpdf.centroid[0].x
gdf_json = gpdf.to_json()
# plot the geojson on the folium webmap
webmap = folium.Map(location = center_pt, zoom_start = 13, min_zoom = 3)
folium.GeoJson(gdf_json, name='data_layer_1').add_to(webmap)
# this opens the webmap
webmap
Output screen capture (of interactive webmap):
Try this, assuming the 'lan' is latitude.
import geopandas as gpd
from shapely.geometry import Polygon
import numpy as np
import pandas as pd
import folium
# ....
def addpolygeom(row):
row_array = np.array(row)
# split dataframe row to a list of tuples (lat, lon)
coords = [tuple(i)[::-1] for i in np.split(row_array, range(2, row_array.shape[0], 2))]
polygon = Polygon(coords)
return polygon
# Convert points to shapely geometry
neightrip_counts_['geometry'] = neightrip_counts_.apply(lambda x: addpolygeom(x), axis=1)
# Create a GeoDataFrame
gdf = gpd.GeoDataFrame(neightrip_counts_, geometry='geometry')
start_coords = [ gdf.centroid[0].y, gdf.centroid[0].x]
gdf_json = gdf.to_json()
map = folium.Map(start_coords, zoom_start=4)
folium.GeoJson(gdf_json, name='mypolygons').add_to(map)
I've been working for a while with Choropleth and Cluster marker maps in Folium (which are great). My question is whether it is possible to combine them in one map, which is so that I can see how much one variable affects another. I can get both map types to work individually so no problems there. This is my attempted code to combine the two so far:
import pandas as pd
import folium
from folium.plugins import MarkerCluster
input_filename="input_filename.csv"
df = pd.read_csv(input_filename,encoding='utf8')
geo = 'blah.json'
comparison = 'comparison.csv'
comparison_data = pd.read_csv(comparison)
m = folium.Map(location=[Lat,Lon], zoom_start=12)
folium.Choropleth(
geo_data=geo,
name='choropleth',
data=comparison_data,
columns=['col1','col2'],
key_on='feature.properties.ID',
fill_color='OrRd',
fill_opacity=0.5,
line_opacity=0.5,
legend_name='Blah (%)'
).add_to(m)
folium.LayerControl().add_to(m)
marker_cluster = MarkerCluster().add_to(m)
for row in df.itertuples():
folium.Marker(location=[row.Lat,row.Lon],popup=row.Postcode).add_to(marker_cluster)
m
It produces the choropleth but won't layer the cluster markers as well. Worth noting that I've had a problem with cluster markers separately where they wouldn't display in Jupyter notebook, but I got around it by saving the file as an html, which was then viewable.
Ok so I've solved it, really pleased!! The solution was to do the marker cluster first, and then follow-up with the Choropleth:
import pandas as pd
import folium
from folium.plugins import MarkerCluster
m = folium.Map(location=[Lat,Lon], zoom_start=12)
input_filename="input_filename.csv"
df = pd.read_csv(input_filename,encoding='utf8')
geo = 'blah.json'
comparison = 'comparison.csv'
comparison_data = pd.read_csv(comparison)
folium.LayerControl().add_to(m)
marker_cluster = MarkerCluster().add_to(m)
for row in df.itertuples():
folium.Marker(location=[row.Lat,row.Lon],popup=row.Postcode).add_to(marker_cluster)
folium.Choropleth(
geo_data=geo,
name='choropleth',
data=comparison_data,
columns=['col1','col2'],
key_on='feature.properties.ID',
fill_color='OrRd',
fill_opacity=0.5,
line_opacity=0.5,
legend_name='Blah (%)'
).add_to(m)
m
from random import randint
import folium
def rgb_to_hex(rgb):
return '#%02x%02x%02x' % rgb
mp = folium.Map(location=[40.6, -73.7], scale = 10)
colors = []
while len(colors) != 50:
r = randint(0, 255)
g = randint(0, 255)
b = randint(0, 255)
if rgb_to_hex((r, g, b)) not in colors:
colors.append(rgb_to_hex((r, g, b)))
for j in range(df.shape[0]):
lat = df.iloc[j]['latitude']
lon = df.iloc[j]['longitude']
color = colors[int(df.iloc[j]['clust'])]
folium.Circle(location=[lat, lon], radius=8, color = color).add_to(mp)
I am trying to render 15,000 points in folium. When I have less than 1000 points I get a map that renders as the attached image (example map). When I include over 1000 my code returns an item void of either a map or points. The following is my code:
z230['marker_color'] = pd.cut(z230['ClosePrice'], bins=5,
labels=['blue','green','yellow','orange','red'])
m = folium.Map(location=[39.2904, -76.6122], zoom_start=12)
for index, row in z230.iterrows():
folium.CircleMarker([row['Latitude'], row['Longitude']],
radius=15, color=row['marker_color']).add_to(m)
m
The only useful workaround I could find was to include cluster markers.
from folium.plugins import FastMarkerCluster
x = #your centering coordinates here LAT
y = #your centering coordinates here LONG
z = #your zoomlevel here
your_map = folium.Map(location=[x, y], tiles="OpenStreetMap", zoom_start=z)
callback = ('function (row) {'
'var circle = L.circle(new L.LatLng(row[0], row[1]), {color: "red", radius: 10000});'
'return circle};')
your_map.add_child(FastMarkerCluster(your_df[['your_LAT_col', 'your_LONG_col']].values.tolist(), callback=callback))
your_map
Would there be a way to plot the borders of the continents with Basemap (or without Basemap, if there is some other way), without those annoying rivers coming along? Especially that piece of Kongo River, not even reaching the ocean, is disturbing.
EDIT: I intend to further plot data over the map, like in the Basemap gallery (and still have the borderlines of the continents drawn as black lines over the data, to give structure for the worldmap) so while the solution by Hooked below is nice, masterful even, it's not applicable for this purpose.
Image produced by:
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
fig = plt.figure(figsize=(8, 4.5))
plt.subplots_adjust(left=0.02, right=0.98, top=0.98, bottom=0.00)
m = Basemap(projection='robin',lon_0=0,resolution='c')
m.fillcontinents(color='gray',lake_color='white')
m.drawcoastlines()
plt.savefig('world.png',dpi=75)
For reasons like this i often avoid Basemap alltogether and read the shapefile in with OGR and convert them to a Matplotlib artist myself. Which is alot more work but also gives alot more flexibility.
Basemap has some very neat features like converting the coordinates of input data to your 'working projection'.
If you want to stick with Basemap, get a shapefile which doesnt contain the rivers. Natural Earth for example has a nice 'Land' shapefile in the physical section (download 'scale rank' data and uncompress). See http://www.naturalearthdata.com/downloads/10m-physical-vectors/
You can read the shapefile in with the m.readshapefile() method from Basemap. This allows you to get the Matplotlib Path vertices and codes in the projection coordinates which you can then convert into a new Path. Its a bit of a detour but it gives you all styling options from Matplotlib, most of which are not directly available via Basemap. Its a bit hackish, but i dont now another way while sticking to Basemap.
So:
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
from matplotlib.collections import PathCollection
from matplotlib.path import Path
fig = plt.figure(figsize=(8, 4.5))
plt.subplots_adjust(left=0.02, right=0.98, top=0.98, bottom=0.00)
# MPL searches for ne_10m_land.shp in the directory 'D:\\ne_10m_land'
m = Basemap(projection='robin',lon_0=0,resolution='c')
shp_info = m.readshapefile('D:\\ne_10m_land', 'scalerank', drawbounds=True)
ax = plt.gca()
ax.cla()
paths = []
for line in shp_info[4]._paths:
paths.append(Path(line.vertices, codes=line.codes))
coll = PathCollection(paths, linewidths=0, facecolors='grey', zorder=2)
m = Basemap(projection='robin',lon_0=0,resolution='c')
# drawing something seems necessary to 'initiate' the map properly
m.drawcoastlines(color='white', zorder=0)
ax = plt.gca()
ax.add_collection(coll)
plt.savefig('world.png',dpi=75)
Gives:
How to remove "annoying" rivers:
If you want to post-process the image (instead of working with Basemap directly) you can remove bodies of water that don't connect to the ocean:
import pylab as plt
A = plt.imread("world.png")
import numpy as np
import scipy.ndimage as nd
import collections
# Get a counter of the greyscale colors
a = A[:,:,0]
colors = collections.Counter(a.ravel())
outside_and_water_color, land_color = colors.most_common(2)
# Find the contigous landmass
land_idx = a == land_color[0]
# Index these land masses
L = np.zeros(a.shape,dtype=int)
L[land_idx] = 1
L,mass_count = nd.measurements.label(L)
# Loop over the land masses and fill the "holes"
# (rivers without outlays)
L2 = np.zeros(a.shape,dtype=int)
L2[land_idx] = 1
L2 = nd.morphology.binary_fill_holes(L2)
# Remap onto original image
new_land = L2==1
A2 = A.copy()
c = [land_color[0],]*3 + [1,]
A2[new_land] = land_color[0]
# Plot results
plt.subplot(221)
plt.imshow(A)
plt.axis('off')
plt.subplot(222)
plt.axis('off')
B = A.copy()
B[land_idx] = [1,0,0,1]
plt.imshow(B)
plt.subplot(223)
L = L.astype(float)
L[L==0] = None
plt.axis('off')
plt.imshow(L)
plt.subplot(224)
plt.axis('off')
plt.imshow(A2)
plt.tight_layout() # Only with newer matplotlib
plt.show()
The first image is the original, the second identifies the land mass. The third is not needed but fun as it ID's each separate contiguous landmass. The fourth picture is what you want, the image with the "rivers" removed.
Following user1868739's example, I am able to select only the paths (for some lakes) that I want:
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
fig = plt.figure(figsize=(8, 4.5))
plt.subplots_adjust(left=0.02, right=0.98, top=0.98, bottom=0.00)
m = Basemap(resolution='c',projection='robin',lon_0=0)
m.fillcontinents(color='white',lake_color='white',zorder=2)
coasts = m.drawcoastlines(zorder=1,color='white',linewidth=0)
coasts_paths = coasts.get_paths()
ipolygons = range(83) + [84] # want Baikal, but not Tanganyika
# 80 = Superior+Michigan+Huron, 81 = Victoria, 82 = Aral, 83 = Tanganyika,
# 84 = Baikal, 85 = Great Bear, 86 = Great Slave, 87 = Nyasa, 88 = Erie
# 89 = Winnipeg, 90 = Ontario
for ipoly in ipolygons:
r = coasts_paths[ipoly]
# Convert into lon/lat vertices
polygon_vertices = [(vertex[0],vertex[1]) for (vertex,code) in
r.iter_segments(simplify=False)]
px = [polygon_vertices[i][0] for i in xrange(len(polygon_vertices))]
py = [polygon_vertices[i][2] for i in xrange(len(polygon_vertices))]
m.plot(px,py,linewidth=0.5,zorder=3,color='black')
plt.savefig('world2.png',dpi=100)
But this only works when using white background for the continents. If I change color to 'gray' in the following line, we see that other rivers and lakes are not filled with the same color as the continents are. (Also playing with area_thresh will not remove those rivers that are connected to ocean.)
m.fillcontinents(color='gray',lake_color='white',zorder=2)
The version with white background is adequate for further color-plotting all kind of land information over the continents, but a more elaborate solution would be needed, if one wants to retain the gray background for continents.
I frequently modify Basemap's drawcoastlines() to avoid those 'broken' rivers. I also modify drawcountries() for the sake of data source consistency.
Here is what I use in order to support the different resolutions available in Natural Earth data:
from mpl_toolkits.basemap import Basemap
class Basemap(Basemap):
""" Modify Basemap to use Natural Earth data instead of GSHHG data """
def drawcoastlines(self):
shapefile = 'data/naturalearth/coastline/ne_%sm_coastline' % \
{'l':110, 'm':50, 'h':10}[self.resolution]
self.readshapefile(shapefile, 'coastline', linewidth=1.)
def drawcountries(self):
shapefile = 'data/naturalearth/countries/ne_%sm_admin_0_countries' % \
{'l':110, 'm':50, 'h':10}[self.resolution]
self.readshapefile(shapefile, 'countries', linewidth=0.5)
m = Basemap(llcrnrlon=-90, llcrnrlat=-40, urcrnrlon=-30, urcrnrlat=+20,
resolution='l') # resolution = (l)ow | (m)edium | (h)igh
m.drawcoastlines()
m.drawcountries()
Here is the output:
Please note that by default Basemap uses resolution='c' (crude), which is not supported in the code shown.
If you're OK with plotting outlines rather than shapefiles, it's pretty easy to plot coastlines that you can get from wherever. I got my coastlines from the NOAA Coastline Extractor in MATLAB format:
http://www.ngdc.noaa.gov/mgg/shorelines/shorelines.html
To edit the coastlines, I converted to SVG, then edited them with Inkscape, then converted back to the lat/lon text file ("MATLAB" format).
All Python code is included below.
# ---------------------------------------------------------------
def plot_lines(mymap, lons, lats, **kwargs) :
"""Plots a custom coastline. This plots simple lines, not
ArcInfo-style SHAPE files.
Args:
lons: Longitude coordinates for line segments (degrees E)
lats: Latitude coordinates for line segments (degrees N)
Type Info:
len(lons) == len(lats)
A NaN in lons and lats signifies a new line segment.
See:
giss.noaa.drawcoastline_file()
"""
# Project onto the map
x, y = mymap(lons, lats)
# BUG workaround: Basemap projects our NaN's to 1e30.
x[x==1e30] = np.nan
y[y==1e30] = np.nan
# Plot projected line segments.
mymap.plot(x, y, **kwargs)
# Read "Matlab" format files from NOAA Coastline Extractor.
# See: http://www.ngdc.noaa.gov/mgg/coast/
lineRE=re.compile('(.*?)\s+(.*)')
def read_coastline(fname, take_every=1) :
nlines = 0
xdata = array.array('d')
ydata = array.array('d')
for line in file(fname) :
# if (nlines % 10000 == 0) :
# print 'nlines = %d' % (nlines,)
if (nlines % take_every == 0 or line[0:3] == 'nan') :
match = lineRE.match(line)
lon = float(match.group(1))
lat = float(match.group(2))
xdata.append(lon)
ydata.append(lat)
nlines = nlines + 1
return (np.array(xdata),np.array(ydata))
def drawcoastline_file(mymap, fname, **kwargs) :
"""Reads and plots a coastline file.
See:
giss.basemap.drawcoastline()
giss.basemap.read_coastline()
"""
lons, lats = read_coastline(fname, take_every=1)
return drawcoastline(mymap, lons, lats, **kwargs)
# =========================================================
# coastline2svg.py
#
import giss.io.noaa
import os
import numpy as np
import sys
svg_header = """<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!-- Created with Inkscape (http://www.inkscape.org/) -->
<svg
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:cc="http://creativecommons.org/ns#"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:svg="http://www.w3.org/2000/svg"
xmlns="http://www.w3.org/2000/svg"
version="1.1"
width="360"
height="180"
id="svg2">
<defs
id="defs4" />
<metadata
id="metadata7">
<rdf:RDF>
<cc:Work
rdf:about="">
<dc:format>image/svg+xml</dc:format>
<dc:type
rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
<dc:title></dc:title>
</cc:Work>
</rdf:RDF>
</metadata>
<g
id="layer1">
"""
path_tpl = """
<path
d="%PATH%"
id="%PATH_ID%"
style="fill:none;stroke:#000000;stroke-width:1px;stroke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1"
"""
svg_footer = "</g></svg>"
# Set up paths
data_root = os.path.join(os.environ['HOME'], 'data')
#modelerc = giss.modele.read_modelerc()
#cmrun = modelerc['CMRUNDIR']
#savedisk = modelerc['SAVEDISK']
ifname = sys.argv[1]
ofname = ifname.replace('.dat', '.svg')
lons, lats = giss.io.noaa.read_coastline(ifname, 1)
out = open(ofname, 'w')
out.write(svg_header)
path_id = 1
points = []
for lon, lat in zip(lons, lats) :
if np.isnan(lon) or np.isnan(lat) :
# Process what we have
if len(points) > 2 :
out.write('\n<path d="')
out.write('m %f,%f L' % (points[0][0], points[0][1]))
for pt in points[1:] :
out.write(' %f,%f' % pt)
out.write('"\n id="path%d"\n' % (path_id))
# out.write('style="fill:none;stroke:#000000;stroke-width:1px;stroke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1"')
out.write(' />\n')
path_id += 1
points = []
else :
lon += 180
lat = 180 - (lat + 90)
points.append((lon, lat))
out.write(svg_footer)
out.close()
# =============================================================
# svg2coastline.py
import os
import sys
import re
# Reads the output of Inkscape's "Plain SVG" format, outputs in NOAA MATLAB coastline format
mainRE = re.compile(r'\s*d=".*"')
lineRE = re.compile(r'\s*d="(m|M)\s*(.*?)"')
fname = sys.argv[1]
lons = []
lats = []
for line in open(fname, 'r') :
# Weed out extraneous lines in the SVG file
match = mainRE.match(line)
if match is None :
continue
match = lineRE.match(line)
# Stop if something is wrong
if match is None :
sys.stderr.write(line)
sys.exit(-1)
type = match.group(1)[0]
spairs = match.group(2).split(' ')
x = 0
y = 0
for spair in spairs :
if spair == 'L' :
type = 'M'
continue
(sdelx, sdely) = spair.split(',')
delx = float(sdelx)
dely = float(sdely)
if type == 'm' :
x += delx
y += dely
else :
x = delx
y = dely
lon = x - 180
lat = 90 - y
print '%f\t%f' % (lon, lat)
print 'nan\tnan'
Okay I think I have a partial solution.
The basic idea is that the paths used by drawcoastlines() are ordered by the size/area. Which means the first N paths are (for most applications) the main land masses and lakes and the later paths the smaller islands and rivers.
The issue is that the first N paths that you want will depend on the projection (e.g., global, polar, regional), if area_thresh has been applied and whether you want lakes or small islands etc. In other words, you will have to tweak this per application.
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
mp = 'cyl'
m = Basemap(resolution='c',projection=mp,lon_0=0,area_thresh=200000)
fill_color = '0.9'
# If you don't want lakes set lake_color to fill_color
m.fillcontinents(color=fill_color,lake_color='white')
# Draw the coastlines, with a thin line and same color as the continent fill.
coasts = m.drawcoastlines(zorder=100,color=fill_color,linewidth=0.5)
# Exact the paths from coasts
coasts_paths = coasts.get_paths()
# In order to see which paths you want to retain or discard you'll need to plot them one
# at a time noting those that you want etc.
for ipoly in xrange(len(coasts_paths)):
print ipoly
r = coasts_paths[ipoly]
# Convert into lon/lat vertices
polygon_vertices = [(vertex[0],vertex[1]) for (vertex,code) in
r.iter_segments(simplify=False)]
px = [polygon_vertices[i][0] for i in xrange(len(polygon_vertices))]
py = [polygon_vertices[i][1] for i in xrange(len(polygon_vertices))]
m.plot(px,py,'k-',linewidth=1)
plt.show()
Once you know the relevant ipoly to stop drawing (poly_stop) then you can do something like this...
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
mproj = ['nplaea','cyl']
mp = mproj[0]
if mp == 'nplaea':
m = Basemap(resolution='c',projection=mp,lon_0=0,boundinglat=30,area_thresh=200000,round=1)
poly_stop = 10
else:
m = Basemap(resolution='c',projection=mp,lon_0=0,area_thresh=200000)
poly_stop = 18
fill_color = '0.9'
# If you don't want lakes set lake_color to fill_color
m.fillcontinents(color=fill_color,lake_color='white')
# Draw the coastlines, with a thin line and same color as the continent fill.
coasts = m.drawcoastlines(zorder=100,color=fill_color,linewidth=0.5)
# Exact the paths from coasts
coasts_paths = coasts.get_paths()
# In order to see which paths you want to retain or discard you'll need to plot them one
# at a time noting those that you want etc.
for ipoly in xrange(len(coasts_paths)):
if ipoly > poly_stop: continue
r = coasts_paths[ipoly]
# Convert into lon/lat vertices
polygon_vertices = [(vertex[0],vertex[1]) for (vertex,code) in
r.iter_segments(simplify=False)]
px = [polygon_vertices[i][0] for i in xrange(len(polygon_vertices))]
py = [polygon_vertices[i][1] for i in xrange(len(polygon_vertices))]
m.plot(px,py,'k-',linewidth=1)
plt.show()
As per my comment to #sampo-smolander
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
fig = plt.figure(figsize=(8, 4.5))
plt.subplots_adjust(left=0.02, right=0.98, top=0.98, bottom=0.00)
m = Basemap(resolution='c',projection='robin',lon_0=0)
m.fillcontinents(color='gray',lake_color='white',zorder=2)
coasts = m.drawcoastlines(zorder=1,color='white',linewidth=0)
coasts_paths = coasts.get_paths()
ipolygons = range(83) + [84]
for ipoly in xrange(len(coasts_paths)):
r = coasts_paths[ipoly]
# Convert into lon/lat vertices
polygon_vertices = [(vertex[0],vertex[1]) for (vertex,code) in
r.iter_segments(simplify=False)]
px = [polygon_vertices[i][0] for i in xrange(len(polygon_vertices))]
py = [polygon_vertices[i][1] for i in xrange(len(polygon_vertices))]
if ipoly in ipolygons:
m.plot(px,py,linewidth=0.5,zorder=3,color='black')
else:
m.plot(px,py,linewidth=0.5,zorder=4,color='grey')
plt.savefig('world2.png',dpi=100)