Fiona简介及Shapefile数据读取

Fiona简介及Shapefile数据读取

Fiona简介及Shapefile数据读取

作者：阿振

Fiona简介

用GDAL的Python绑定API书写程序有没有一种仍然在写C/C++的感觉，Fiona基于GDAL提供了更加Pythonic的读取空间矢量数据的API，参见：​​图层（Layer）- 要素（Feature）- 属性和几何体（Attributes and Geometry）

Fiona采用Python中内置的数据结构表示矢量数据，一个要素以GeoJSON表示，使用Python内置的字典（​​dict​​​）结构组织；一个图层包含在一个集合中（​​Collection​​）。可以对该集合进行迭代遍历，得到其中的要素。

要素是以GeoJSON表示的，结构如下：

{'type': 'Feature', 'id': '0', 'geometry': {'type': 'Polygon', 'coordinates': [[(96.416, 42.7588), (96.416, 42.7148), (95.9766, 42.4951), (96.0645, 42.3193), (96.2402, 42.2314), (95.9766, 41.9238), (95.2734, 41.6162), (95.1855, 41.792), (94.5703, 41.4844), (94.043, 41.0889), (93.8672, 40.6934), (93.0762, 40.6494), (92.6367, 39.6387), (92.373, 39.3311), (92.373, 39.1113), (92.373, 39.0234), (90.1758, 38.4961), (90.3516, 38.2324), (90.6152, 38.3203), (90.5273, 37.8369), (91.0547, 37.4414), (91.3184, 37.0898), (90.7031, 36.7822), (90.791, 36.6064), (91.0547, 36.5186), (91.0547, 36.0791), (90.8789, 36.0352), (90.0, 36.2549), (89.9121, 36.0791), (89.7363, 36.0791), (89.209, 36.2988), (88.7695, 36.3428), (88.5938, 36.4746), (87.3633, 36.4307), (86.2207, 36.167), (86.1328, 35.8594), (85.6055, 35.6836), (85.0781, 35.7275), (84.1992, 35.376), (83.1445, 35.4199), (82.8809, 35.6836), (82.4414, 35.7275), (82.002, 35.332), (81.6504, 35.2441), (80.4199, 35.4199), (80.2441, 35.2881), (80.332, 35.1563), (80.2441, 35.2002), (79.8926, 34.8047), (79.8047, 34.4971), (79.1016, 34.4531), (79.0137, 34.3213), (78.2227, 34.7168), (78.0469, 35.2441), (78.0469, 35.5078), (77.4316, 35.4639), (76.8164, 35.6396), (76.5527, 35.8594), (76.2012, 35.8154), (75.9375, 36.0352), (76.0254, 36.4746), (75.8496, 36.6943), (75.498, 36.7383), (75.4102, 36.958), (75.0586, 37.002), (74.8828, 36.9141), (74.7949, 37.0459), (74.5313, 37.0898), (74.5313, 37.2217), (74.8828, 37.2217), (75.1465, 37.4414), (74.8828, 37.5732), (74.9707, 37.749), (74.8828, 38.4521), (74.3555, 38.6719), (74.1797, 38.6719), (74.0918, 38.54), (73.8281, 38.584), (73.7402, 38.8477), (73.8281, 38.9795), (73.4766, 39.375), (73.916, 39.5068), (73.916, 39.6826), (73.8281, 39.7705), (74.0039, 40.0342), (74.8828, 40.3418), (74.7949, 40.5176), (75.2344, 40.4297), (75.5859, 40.6494), (75.7617, 40.2979), (76.377, 40.3857), (76.9043, 41.001), (77.6074, 41.001), (78.1348, 41.2207), (78.1348, 41.3965), (80.1563, 42.0557), (80.2441, 42.2754), (80.1563, 42.627), (80.2441, 42.8467), (80.5078, 42.8906), (80.4199, 43.0664), (80.7715, 43.1982), (80.4199, 44.165), (80.4199, 44.6045), (79.9805, 44.8242), (79.9805, 44.9561), (81.7383, 45.3955), (82.0898, 45.2197), (82.5293, 45.2197), (82.2656, 45.6592), (83.0566, 47.2412), (83.6719, 47.0215), (84.7266, 47.0215), (84.9023, 46.8896), (85.5176, 47.0654), (85.6934, 47.2852), (85.5176, 48.1201), (85.7813, 48.4277), (86.5723, 48.5596), (86.8359, 48.8232), (86.748, 48.9551), (86.8359, 49.1309), (87.8027, 49.1748), (87.8906, 48.999), (87.7148, 48.9111), (88.0664, 48.7354), (87.9785, 48.6035), (88.5059, 48.3838), (88.6816, 48.1641), (89.1211, 47.9883), (89.5605, 48.0322), (89.7363, 47.8564), (90.0879, 47.8564), (90.3516, 47.6807), (90.5273, 47.2412), (90.8789, 46.9775), (91.0547, 46.582), (90.8789, 46.3184), (91.0547, 46.0107), (90.7031, 45.7471), (90.7031, 45.5273), (90.8789, 45.2197), (91.582, 45.0879), (93.5156, 44.9561), (94.7461, 44.3408), (95.3613, 44.2969), (95.3613, 44.0332), (95.5371, 43.9014), (95.8887, 43.2422), (96.3281, 42.9346), (96.416, 42.7588)]]}, 'properties': OrderedDict([('Name', '新疆维吾尔自治区'), ('CenterX', 84.9023), ('CenterY', 42.148)])}

Shapefile数据读取

下面我们来体验一下Fiona的简洁之处，主要是使用Python内置的结构表示所有数据，所以使用Fiona操作空间数据就像操作Python内置的数据结构一样简单。

import fionawith fiona.open('China.shp', encoding='utf-8') as c: # 输出数据的基本信息 print(f'数据范围：{c.bounds}') print(f'投影定义：{c.crs}') print(f'数据格式：{c.driver}') print(f'数据编码：{c.encoding}') # 输出文件的属性字段信息 fields = c.schema['properties'] print('文件的属性字段信息：') for k, v in fields.items(): print(f'{k} -> {v}') # 遍历集合中的要素 # f是一个tuple，第一个元素是要素编号，第二个是dict格式的要素 for f in c.items(): # 输入要素的详细信息 # 要素是以GeoJSON表示的 print(f[1]['properties']['Name'])

特别需要注意数据的编码问题，要不然默认的编码会引起中文乱码，常见中文编码可能采用GBK或者UTF-8等。

输出结果如下：

数据范围：(73.4766, 18.1055, 135.0879, 53.5693)投影定义：{'init': 'epsg:4326'}数据格式：ESRI Shapefile数据编码：utf-8文件的属性字段信息：Name -> str:24CenterX -> float:24.15CenterY -> float:24.15

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