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zorder of drawmapboundary() gets on top of imshow() #474

@Xunius

Description

@Xunius

Hi all,

I got this weird issue that changing the order of drawmapboundary() wrt drawparallels() and drawmeridians() gives different results. Specifically, calling drawmapboundary(fill_color='0.8') first leads to an overlay of grey over the imshow() (see left panel in figure). While putting drawmapboundary() after drawparallels() and drawmeridians() gives correct results (right panel in figure).

basemap

The script to create that plot:

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap

def plotBmap(data, x, y, ax, order):

    bmap=Basemap(projection='cyl',\
            llcrnrlat=y[0],llcrnrlon=x[0],\
            urcrnrlat=y[-1],urcrnrlon=x[-1],\
            ax=ax)

    bmap.imshow(data, interpolation='nearest')

    # plot axes labels
    lat_labels=np.linspace(-90, 90, 5)
    lon_labels=np.linspace(0, 360, 6)
    ax.set_yticks(lat_labels)
    ax.set_xticks(lon_labels)
    ax.tick_params(axis='both',which='major',labelsize=10)
    ax.xaxis.set_ticklabels([])
    ax.yaxis.set_ticklabels([])

    # draw continents
    bmap.drawcoastlines(linewidth=1.5,linestyle='solid',color='k',\
        antialiased=True)
    bmap.drawcountries(linewidth=0.5,linestyle='solid',color='k',\
            antialiased=True)

    if order=='before':
        bmap.drawmapboundary(color='k',linewidth=1.0,fill_color='0.8')
        bmap.drawparallels(lat_labels,labels=[1,1,0,0],linewidth=0,\
                labelstyle='+/-',fontsize=10)
        bmap.drawmeridians(lon_labels,labels=[0,0,0,1],linewidth=0,\
                labelstyle='+/-',fontsize=10)
    elif order=='after':
        bmap.drawparallels(lat_labels,labels=[1,1,0,0],linewidth=0,\
                labelstyle='+/-',fontsize=10)
        bmap.drawmeridians(lon_labels,labels=[0,0,0,1],linewidth=0,\
                labelstyle='+/-',fontsize=10)
        bmap.drawmapboundary(color='k',linewidth=1.0,fill_color='0.8')

    return bmap

if __name__=='__main__':

    x=np.arange(0, 361, 1)     # lon
    y=np.arange(-90, 91, 1)    # lat
    X,Y=np.meshgrid(x,y)
    z=np.sin(X/90.)+np.cos(Y/90.)

    # create an area of missings
    z[10:50, 20:80]=np.nan

    fig, (ax1, ax2)=plt.subplots(1, 2, figsize=(12,6))

    bmap1=plotBmap(z, x, y, ax1, 'before')
    ax1.set_title('before')

    bmap2=plotBmap(z, x, y, ax2, 'after')
    ax2.set_title('after')

    fig.show()

I guess it's the zorder that is wrong. specifying zorder=0 in drawmapboundary() doesn't work, by zordre=-1 does.

The versions of relevant packages:

  • basemap = 1.2.0
  • matplotlib = 2.2.3

One of the combinations that doesn't have this issue:

  • basemap = 1.0.7
  • matplotlib = 2.2.3

Activity

changed the title [-]order of `drawmapboundary` gives different results[/-] [+]zorder of `drawmapboundary()` gets on top of `imshow()`[/+] on Aug 21, 2019
changed the title [-]zorder of `drawmapboundary()` gets on top of `imshow()`[/-] [+]zorder of drawmapboundary() gets on top of imshow()[/+] on Aug 21, 2019
WeatherGod

WeatherGod commented on Aug 21, 2019

@WeatherGod
Member
Xunius

Xunius commented on Dec 9, 2019

@Xunius
Author

Hi, I wonder is there any fix being patched, but I noticed something new.

I created a new conda environment and installed basemap = 1.2.0 and matplotlib = 2.2.3. Now setting zorder=-1 in drawmapboundary() makes the top and the left hand side black frames gone (see top-right in figure below), as if the fill_color is overlaying the figure frame. Again it seems to be related to the ordering of drawmapboundary() wrt drawparallels() and drawmeridians(). I've created a new plot to show this:

basemap2

Code below:

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap

def plotBmap(data, x, y, ax, method):

    bmap=Basemap(projection='cyl',\
            llcrnrlat=y[0],llcrnrlon=x[0],\
            urcrnrlat=y[-1],urcrnrlon=x[-1],\
            ax=ax)

    bmap.imshow(data, interpolation='nearest')

    # plot axes labels
    lat_labels=np.linspace(-90, 90, 5)
    lon_labels=np.linspace(0, 360, 6)
    ax.set_yticks(lat_labels)
    ax.set_xticks(lon_labels)
    ax.tick_params(axis='both',which='major',labelsize=10)
    ax.xaxis.set_ticklabels([])
    ax.yaxis.set_ticklabels([])

    # draw continents
    bmap.drawcoastlines(linewidth=1.5,linestyle='solid',color='k',\
        antialiased=True)
    bmap.drawcountries(linewidth=0.5,linestyle='solid',color='k',\
            antialiased=True)

    if method=='before no zorder':
        bmap.drawmapboundary(color='k',linewidth=1.0,fill_color='0.8')
        bmap.drawparallels(lat_labels,labels=[1,1,0,0],linewidth=0,\
                labelstyle='+/-',fontsize=10)
        bmap.drawmeridians(lon_labels,labels=[0,0,0,1],linewidth=0,\
                labelstyle='+/-',fontsize=10)
    elif method=='before with zorder':
        bmap.drawmapboundary(color='k',linewidth=1.0,fill_color='0.8', zorder=-1)
        bmap.drawparallels(lat_labels,labels=[1,1,0,0],linewidth=0,\
                labelstyle='+/-',fontsize=10)
        bmap.drawmeridians(lon_labels,labels=[0,0,0,1],linewidth=0,\
                labelstyle='+/-',fontsize=10)
    elif method=='after no zorder':
        bmap.drawparallels(lat_labels,labels=[1,1,0,0],linewidth=0,\
                labelstyle='+/-',fontsize=10)
        bmap.drawmeridians(lon_labels,labels=[0,0,0,1],linewidth=0,\
                labelstyle='+/-',fontsize=10)
        bmap.drawmapboundary(color='k',linewidth=1.0,fill_color='0.8')
    elif method=='after with zorder':
        bmap.drawparallels(lat_labels,labels=[1,1,0,0],linewidth=0,\
                labelstyle='+/-',fontsize=10)
        bmap.drawmeridians(lon_labels,labels=[0,0,0,1],linewidth=0,\
                labelstyle='+/-',fontsize=10)
        bmap.drawmapboundary(color='k',linewidth=1.0,fill_color='0.8', zorder=-1)

    ax.set_title(method)

    return bmap


if __name__=='__main__':

    x=np.arange(0, 361, 1)     # lon
    y=np.arange(-90, 91, 1)    # lat
    X,Y=np.meshgrid(x,y)
    z=np.sin(X/90.)+np.cos(Y/90.)

    # create an area of missings
    z[10:50, 20:80]=np.nan

    fig, axes=plt.subplots(2, 2, figsize=(12,6))

    bmap1=plotBmap(z, x, y, axes[0,0], 'before no zorder')
    bmap1=plotBmap(z, x, y, axes[0,1], 'before with zorder')
    bmap1=plotBmap(z, x, y, axes[1,0], 'after no zorder')
    bmap1=plotBmap(z, x, y, axes[1,1], 'after with zorder')

    fig.show()

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          zorder of drawmapboundary() gets on top of imshow() · Issue #474 · matplotlib/basemap