zorder for individual points in a scatter plot on a Basemap

Community matplotlib-users
1

Hi,

I’m currently using a scatter plot on a Basemap and I’d like to set the
zorder of the individual points based on their temperature. The
higher the temperature, the higher the zorder. Also, i’m using a
colorbar to set the colors for the plot. Here is a snippet of my code:

    x = np.array(val)

    fig.sca(ax1)

    lon_0 =(urcrnrlon+llcrnrlon)/2

    lat_0 =(urcrnrlat+llcrnrlat)/2

    m =

Basemap(llcrnrlon=llcrnrlon,llcrnrlat=llcrnrlat,urcrnrlon=urcrnrlon,

urcrnrlat=urcrnrlat,resolution=‘i’,projection=‘cyl’,lon_0=lon_0,lat_0=lat_0)

    m.drawcoastlines()

    m.drawmapboundary()

    m.drawparallels(np.arange(llcrnrlat-1,urcrnrlat+1,5.))

    m.drawmeridians(np.arange(llcrnrlon-1,urcrnrlon+1,5.))

    m.fillcontinents(color='white',lake_color='aqua')

    m.drawcountries(linewidth=1)

    lons,lats = m(lon,lat)

   

    #I can do it this way, but this screws up the colorbar

    #for i in range(len(x)):
··· 
    #

m.scatter(lons[i],lats[i],c=x[i],marker=‘o’,picker=5,zorder=x[i])

    m.scatter(lons,lats,c=x,marker='o',picker=5)   

    plt.title('Time Range: %s to %s'%(startDay.strftime("%b-%d

%H:%M"),endDay.strftime("%b-%d %H:%M")))

    plt.colorbar(shrink=0.5)

Is there anyway to set the zorder of the points without using the loop
in commented code? Any help would be greatly appreciated.

Thanks,

Aman

2

Hi,

What about ordering the arrays before plotting ? Are the first elements drawn back to front ?

Thomas

···

Thomas Lecocq
Geologist
Ph.D.Student (Seismology)
Royal Observatory of Belgium

Date: Mon, 28 Jun 2010 12:55:22 -0400
From: athakral@…3179…
To: matplotlib-users@lists.sourceforge.net
Subject: [Matplotlib-users] zorder for individual points in a scatter plot on a Basemap

Hi,

I’m currently using a scatter plot on a Basemap and I’d like to set the zorder of the individual points based on their temperature. The higher the temperature, the higher the zorder. Also, i’m using a colorbar to set the colors for the plot. Here is a snippet of my code:

    x = np.array(val)
    fig.sca(ax1)
    lon_0 =(urcrnrlon+llcrnrlon)/2
    lat_0 =(urcrnrlat+llcrnrlat)/2
    m =     Basemap(llcrnrlon=llcrnrlon,llcrnrlat=llcrnrlat,urcrnrlon=urcrnrlon,
            urcrnrlat=urcrnrlat,resolution='i',projection='cyl',lon_0=lon_0,lat_0=lat_0)
    m.drawcoastlines()
    m.drawmapboundary()
    m.drawparallels(np.arange(llcrnrlat-1,urcrnrlat+1,5.))
    m.drawmeridians(np.arange(llcrnrlon-1,urcrnrlon+1,5.))
    m.fillcontinents(color='white',lake_color='aqua')
    m.drawcountries(linewidth=1)
    lons,lats = m(lon,lat)
   
    #I can do it this way, but this screws up the colorbar
    #for i in range(len(x)):
    #    m.scatter(lons[i],lats[i],c=x[i],marker='o',picker=5,zorder=x[i])   

    m.scatter(lons,lats,c=x,marker='o',picker=5)   
    plt.title('Time Range: %s to %s'%(startDay.strftime("%b-%d %H:%M"),endDay.strftime("%b-%d %H:%M")))
    plt.colorbar(shrink=0.5)

Is there anyway to set the zorder of the points without using the loop in commented code? Any help would be greatly appreciated.

Thanks,

Aman

3

Aman: You can save the mappable from the scatter you want the colorbar
to represent, then pass that to colorbar. i.e.

im = m.scatter(lons,lats,c=x,marker=‘o’,picker=5) # plot all the pts,
save mappable

now do one at a time

for i in range(len(x)):

m.scatter(lons[i],lats[i],c=x[i],marker='o',picker=5,zorder=x[i])

plt.colorbar(im,shrink=0.5) # use mappable from 1st call to scatter for
colorbar

-Jeff

···

athakral@…3179…
matplotlib-users@lists.sourceforge.net

    x = np.array(val)

    fig.sca(ax1)

    lon_0 =(urcrnrlon+llcrnrlon)/2

    lat_0 =(urcrnrlat+llcrnrlat)/2
    m =

Basemap(llcrnrlon=llcrnrlon,llcrnrlat=llcrnrlat,urcrnrlon=urcrnrlon,

urcrnrlat=urcrnrlat,resolution=‘i’,projection=‘cyl’,lon_0=lon_0,lat_0=lat_0)

    m.drawcoastlines()

    m.drawmapboundary()

    m.drawparallels(np.arange(llcrnrlat-1,urcrnrlat+1,5.))

    m.drawmeridians(np.arange(llcrnrlon-1,urcrnrlon+1,5.))

    m.fillcontinents(color='white',lake_color='aqua')

    m.drawcountries(linewidth=1)

    lons,lats = m(lon,lat)

   

    #I can do it this way, but this screws up the colorbar

    #for i in range(len(x)):

    #

m.scatter(lons[i],lats[i],c=x[i],marker=‘o’,picker=5,zorder=x[i])

    m.scatter(lons,lats,c=x,marker='o',picker=5)   

    plt.title('Time Range: %s to %s'%(startDay.strftime("%b-%d

%H:%M"),endDay.strftime("%b-%d %H:%M")))

    plt.colorbar(shrink=0.5)

-- Jeffrey S. Whitaker Phone : (303)497-6313
Meteorologist FAX : (303)497-6449
NOAA/OAR/PSD R/PSD1 Email : 325 Broadway Office : Skaggs Research Cntr 1D-113
Boulder, CO, USA 80303-3328 Web :

Jeffrey.S.Whitaker@…259…http://tinyurl.com/5telg

4

Hi,

Thanks for the suggestions. I also came the same conclusion
about ordering the arrays before hand. This did the trick for the zorder, but I also have to make the marker unique for each data point. I
need to keep everything into one artist since I’m using a pick event to
display the data represented by that point. I’m not sure how I can use
just 1 Artist, but get a variety of distinct shapes (circles, squares, and triangles should be sufficient).

Thanks so much!
Aman

PS. Sorry about the duplicate emails Jeff. I forgot to hit “Reply to All” the first time.

···

On Tue, Jun 29, 2010 at 3:39 PM, Jeff Whitaker <jswhit@…146…> wrote:

On 6/29/10 1:19 PM, Thomas Lecocq wrote:

Hi,

What about ordering the arrays before plotting ? Are the first elements
drawn back to front ?

Thomas

Thomas Lecocq

Geologist

Ph.D.Student (Seismology)

Royal Observatory of Belgium

Date: Mon, 28 Jun 2010 12:55:22 -0400

From: athakral@…83…3179…

To: matplotlib-users@lists.sourceforge.net

Subject: [Matplotlib-users] zorder for individual points in a scatter
plot on a Basemap

Hi,

I’m currently using a scatter plot on a Basemap and I’d like to set the
zorder of the individual points based on their temperature. The
higher the temperature, the higher the zorder. Also, i’m using a
colorbar to set the colors for the plot. Here is a snippet of my code:

      x = np.array(val)

    fig.sca(ax1)

    lon_0 =(urcrnrlon+llcrnrlon)/2

    lat_0 =(urcrnrlat+llcrnrlat)/2

      m =

Basemap(llcrnrlon=llcrnrlon,llcrnrlat=llcrnrlat,urcrnrlon=urcrnrlon,

urcrnrlat=urcrnrlat,resolution=‘i’,projection=‘cyl’,lon_0=lon_0,lat_0=lat_0)

    m.drawcoastlines()

    m.drawmapboundary()

    m.drawparallels(np.arange(llcrnrlat-1,urcrnrlat+1,5.))

    m.drawmeridians(np.arange(llcrnrlon-1,urcrnrlon+1,5.))

    m.fillcontinents(color='white',lake_color='aqua')

    m.drawcountries(linewidth=1)

    lons,lats = m(lon,lat)

   

    #I can do it this way, but this screws up the colorbar

    #for i in range(len(x)):

    #

m.scatter(lons[i],lats[i],c=x[i],marker=‘o’,picker=5,zorder=x[i])

    m.scatter(lons,lats,c=x,marker='o',picker=5)   

    plt.title('Time Range: %s to %s'%(startDay.strftime("%b-%d

%H:%M"),endDay.strftime(“%b-%d %H:%M”)))

    plt.colorbar(shrink=0.5)

Is there anyway to set the zorder of the points without using the loop
in commented code? Any help would be greatly appreciated.

Thanks,

Aman: You can save the mappable from the scatter you want the colorbar
to represent, then pass that to colorbar. i.e.

im = m.scatter(lons,lats,c=x,marker=‘o’,picker=5) # plot all the pts,
save mappable

now do one at a time

for i in range(len(x)):

m.scatter(lons[i],lats[i],c=x[i],marker='o',picker=5,zorder=x[i])

plt.colorbar(im,shrink=0.5) # use mappable from 1st call to scatter for
colorbar

-Jeff

-- Jeffrey S. Whitaker Phone : (303)497-6313
Meteorologist FAX : (303)497-6449
NOAA/OAR/PSD R/PSD1 Email : Jeffrey.S.Whitaker@...259...
325 Broadway Office : Skaggs Research Cntr 1D-113
Boulder, CO, USA 80303-3328 Web : [http://tinyurl.com/5telg](http://tinyurl.com/5telg)

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B.Eng & Biosci, M.Eng Design