Created
August 4, 2018 14:23
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Escritura y lectura de estructuras de datos anidadas en formato binario. OrtizOL.
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import struct | |
import itertools | |
def escribir_polilineas(archivo, polilineas): | |
lista_plana = list(itertools.chain(*polilineas)) | |
min_x = min(x for x, y in lista_plana) | |
max_x = max(x for x, y in lista_plana) | |
min_y = min(y for x, y in lista_plana) | |
max_y = max(y for x, y in lista_plana) | |
with open(archivo, 'wb') as f: | |
f.write(struct.pack('<iddddi', | |
0x1234, | |
min_x, min_y, | |
max_x, max_y, | |
len(polilineas))) | |
for polilinea in polilineas: | |
tamahnio = len(polilinea) * struct.calcsize('<dd') | |
f.write(struct.pack('<i', tamahnio + 4)) | |
for punto in polilinea: | |
f.write(struct.pack('<dd', *punto)) | |
def leer_polilineas(archivo): | |
with open(archivo, 'rb') as f: | |
encabezado = f.read(40) | |
codigo, min_x, min_y, max_x, max_y, numero_polilineas = struct.unpack('<iddddi', encabezado) | |
polilineas = [] | |
for n in range(numero_polilineas): | |
bytes_punto, = struct.unpack('<i', f.read(4)) | |
polilinea = [] | |
for m in range(bytes_punto // 16): | |
punto = struct.unpack('<dd', f.read(16)) | |
polilinea.append(punto) | |
polilineas.append(polilinea) | |
return polilineas | |
polilineas = [ | |
[(1.0, 2.5), (3.5, 4.0), (2.5, 1.5)], | |
[(7.0, 1.2), (5.1, 3.0), (0.5, 7.5), (0.8, 9.0)], | |
[(3.4, 6.3), (1.2, 0.5), (4.6, 9.2)] | |
] | |
escribir_polilineas('polilineas.bin', polilineas) | |
print(leer_polilineas('polilineas.bin')) |
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