wm

Wang–Müller line generalization algorithm in PostGIS
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layer2img.py (4136B) - Raw

      1 #!/usr/bin/python3
      2 """
      3 Convert PostGIS geometries to an image. To scale.
      4 
      5 Accepts a few geometry fine-tuning parameters.
      6 """
      7 
      8 import argparse
      9 import geopandas
     10 import psycopg2
     11 from matplotlib import rc
     12 import matplotlib.pyplot as plt
     13 
     14 CMAP = 'tab20c'  # 'Set3'  # is nice too
     15 PSQL_CREDS = "host=127.0.0.1 dbname=osm user=osm password=osm"
     16 COLORS = {
     17     'black': '#000000',
     18     'green': '#1b9e77',
     19     'orange': '#d95f02',
     20     'purple': '#7570b3',
     21 }
     22 # see `NOTICE` in the LaTeX document; this is the width of the main text block.
     23 TEXTWIDTH_CM = 12.12364
     24 
     25 QUADRANTS = {'tr':1, 'tl':2, 'bl':3, 'br':4}
     26 
     27 def color(string):
     28     return COLORS[string if string else 'black']
     29 
     30 
     31 def inch(cm):
     32     return cm / 2.54
     33 
     34 
     35 def parse_args():
     36     kwcolor = {'type': color, 'default': 'black'}
     37     parser = argparse.ArgumentParser(description=__doc__)
     38     parser.add_argument('--g1-select')
     39     parser.add_argument('--g1-linestyle')
     40     parser.add_argument('--g1-label')
     41     parser.add_argument('--g1-color', **kwcolor)
     42     parser.add_argument('--g2-select')
     43     parser.add_argument('--g2-linestyle')
     44     parser.add_argument('--g2-label')
     45     parser.add_argument('--g2-color', **kwcolor)
     46     parser.add_argument('--g3-select')
     47     parser.add_argument('--g3-linestyle')
     48     parser.add_argument('--g3-label')
     49     parser.add_argument('--g3-color', **kwcolor)
     50     parser.add_argument('--legend',
     51             help="Legend location, following matplotlib rules", default='best')
     52     parser.add_argument('--widthdiv', default=1, type=float,
     53             help="Divide the width by this number "
     54             "(useful when two images are laid horizontally "
     55             "in the resulting file")
     56     parser.add_argument('--quadrant', choices=QUADRANTS.keys(),
     57             help="Image is comprised of 4 quadrants. This variable, "
     58             "when non-empty, will clip and return the requested quadrant")
     59     parser.add_argument('--outfile', metavar='<file>',
     60             help="If unset, displayed on the screen")
     61     return parser.parse_args()
     62 
     63 
     64 def read_layer(select, width, maybe_quadrant):
     65     if not select:
     66         return
     67     way = "way"
     68     if maybe_quadrant:
     69         way = "wm_quadrant(way, {})".format(QUADRANTS[maybe_quadrant])
     70 
     71     conn = psycopg2.connect(PSQL_CREDS)
     72     sql = "SELECT {way} as way1 FROM {select}".format(way=way, select=select)
     73 
     74     return geopandas.read_postgis(sql, con=conn, geom_col='way1')
     75 
     76 
     77 def plot_args(geom, color, maybe_linestyle, maybe_label):
     78     if geom is None:
     79         return
     80 
     81     # polygons either have fillings or lines
     82     if geom.geom_type[0] == 'Polygon':
     83         if maybe_linestyle:
     84             return {
     85                 'edgecolor': 'black',
     86                 'linestyle': maybe_linestyle,
     87                 'color': (0, 0, 0, 0),
     88             }
     89         else:
     90             return {'cmap': CMAP, 'alpha': .25}
     91 
     92     r = {'color': color}
     93     if maybe_linestyle == 'invisible':
     94         r['color'] = (0, 0, 0, 0)
     95     elif maybe_linestyle:
     96         r['linestyle'] = maybe_linestyle
     97 
     98     if maybe_label:
     99         r['label'] = '\\normalfont %s' % maybe_label
    100 
    101     return r
    102 
    103 
    104 def main():
    105     args = parse_args()
    106     width = TEXTWIDTH_CM / args.widthdiv
    107     g1 = read_layer(args.g1_select, width, args.quadrant)
    108     g2 = read_layer(args.g2_select, width, args.quadrant)
    109     g3 = read_layer(args.g3_select, width, args.quadrant)
    110     c1 = plot_args(g1, args.g1_color, args.g1_linestyle, args.g1_label)
    111     c2 = plot_args(g2, args.g2_color, args.g2_linestyle, args.g2_label)
    112     c3 = plot_args(g3, args.g3_color, args.g3_linestyle, args.g3_label)
    113 
    114     rc('text', usetex=True)
    115     rc('text.latex', preamble='\\usepackage{numprint}\n')
    116     fig, ax = plt.subplots(constrained_layout=True)
    117     fig.set_figwidth(inch(width))
    118 
    119     g1 is not None and g1.plot(ax=ax, linewidth=.75, **c1)
    120     g2 is not None and g2.plot(ax=ax, linewidth=.75, **c2)
    121     g3 is not None and g3.plot(ax=ax, linewidth=.75, **c3)
    122 
    123     ax.legend(loc=args.legend, frameon=False)
    124     ax.axis('off')
    125     ax.margins(0, 0)
    126     if args.outfile:
    127         fig.savefig(args.outfile, bbox_inches='tight', dpi=600)
    128     else:
    129         plt.show()
    130 
    131 
    132 if __name__ == '__main__':
    133     main()