maskout.py

# -*- coding: utf-8 -*-
########################################################################################################################
# ### This module enables you to maskout the unneccessary data outside the
#                     interest region on a matplotlib-plotted output instance
# ################### in an effecient way,You can use this script for free   ###########################################
# ######################################################################################################################
# ####USAGE:INPUT include 'originfig':the matplotlib instance##
#                         'ax': the Axes instance
#                         'shapefile': the shape file used for generating a basemap A
#                         'region':the name of a region of on the basemap A,outside the region the data is to be maskout
#           OUTPUT    is  'clip' :the the masked-out or clipped matplotlib instance.
import shapefile
from matplotlib.path import Path
from matplotlib.patches import PathPatch


def getPathFromShp(shpfile, region, encoding="utf-8"):
    try:
        sf = shapefile.Reader(shpfile, encoding=encoding)
        vertices = []  # 这块是已经修改的地方
        codes = []  # 这块是已经修改的地方
        paths = []
        for shape_rec in sf.shapeRecords():
            # if shape_rec.record[3] == region:  # 这里需要找到和region匹配的唯一标识符，record[]中必有一项是对应的。
            if region == [100000] or shape_rec.record[4] in region:  # 这块是已经修改的地方
                pts = shape_rec.shape.points
                prt = list(shape_rec.shape.parts) + [len(pts)]
                for i in range(len(prt) - 1):
                    for j in range(prt[i], prt[i + 1]):
                        vertices.append((pts[j][0], pts[j][1]))
                    codes += [Path.MOVETO]
                    codes += [Path.LINETO] * (prt[i + 1] - prt[i] - 2)
                    codes += [Path.CLOSEPOLY]
                path = Path(vertices, codes)
                paths.append(path)
        if paths:
            path = Path.make_compound_path(*paths)
        else:
            path = None
        return path
    except Exception as err:
        print(err)
        return None


def shp2clip(originfig, ax, shpfile, region, encoding=None):
    if encoding is None:
        encoding = "utf-8"
    path = getPathFromShp(shpfile=shpfile, region=region, encoding=encoding)
    patch = None
    if path:
        patch = PathPatch(
            path, transform=ax.transData, facecolor="none", edgecolor="black"
        )
        for contour in originfig.collections:
            contour.set_clip_path(patch)
    return path, patch