igraph第一天，利用make_lattice画出各个维度在二维的映射

make_lattice(length = 1,dim=1) -> a;plot(a) make_lattice(length = 2,dim=2) -> a;plot(a) make_lattice(length = 2,dim=3) -> a;plot(a) make_lattice(length = 2,dim=4) -> a;plot(a) make_lattice(length = 2,dim=5) -> a;plot(a) make_lattice(length = 2,dim=6) -> a;plot(a) make_lattice(length = 2,dim=7) -> a;plot(a) make_lattice(length = 2,dim=8) -> a;plot(a) make_lattice(length = 2,dim=9) -> a;plot(a) make_lattice(length = 2,dim=10) -> a;plot(a) make_lattice(length = 2,dim=11) -> a;plot(a) make_lattice(length = 2,dim=12) -> a;plot(a) make_lattice(length = 2,dim=13) -> a;plot(a) make_lattice(length = 2,dim=14) -> a;plot(a)