有一大推geojson数据,现在需要对其进行坐标转换,geojson数据示例
coordinates = [119,35]
coordinates = [[119,35],[119,35]]
coordinates = [[[119,35],[119,35]],[[119,35],[119,35]]]
期望转换后的坐标:
coordinates = [11900,3500]
coordinates = [[11900,3500],[11900,3500]]
coordinates = [[[11900,3500],[11900,3500]],[[11900,3500],[11900,3500]]]
怎么遍历到每一个position(坐标对)?
我现在是这么做的:
def transform(x,y,other_parameter):
return ....
def miterator(ary,mapper):
if isinstance(ary,list):
if isinstance(ary[0],list):
for el in ary:
miterator(el, mapper)
else:
ary[0],ary[1] = mapper(ary[0],ary[1])
def logic(...):
other_parameter= ....
coordinates = get_coordinates(..)
miterator(coordinates,transform) #??????
然后问题就出来了,我怎么把other_parameter传到transform里面?
所以 我希望最好通过generator方式:
def xgenerator(ary):
if xx:
...
yield(x,y)
然后我就可以通过这种方式调用:
def logic(...):
other_parameter= ....
coordinates = get_coordinates(..)
for x,y in xgenerator(coordinates):
transform(x,y,other_parameter)
但是这个generator我死活写不出来,怎么破?
很早之前在OSC上留过一个
def dft(tree):
try:
for c in tree:
for e in dft(c):
yield e
except TypeError:
pass
yield tree
http://www.oschina.net/code/snippet_724613_13019
这样?
#!/usr/bin/env python3
def convert(L):
ret = []
for x in L:
if isinstance(x, (int, float)):
ret.append(x * 100)
else:
ret.append(convert(x))
return ret
if __name__ == '__main__':
a = [119,35]
b = [[119,35],[119,35]]
c = [[[119,35],[119,35]],[[119,35],[119,35]]]
print(convert(a))
print(convert(b))
print(convert(c))
把坐标一个个地 yield 出来的版本:
def convert(L):
if isinstance(L[0], (int, float)):
yield L
else:
for x in L:
yield from convert(x)
Python 3.2 及以下:
def convert(L):
if isinstance(L[0], (int, float)):
yield L
else:
for x in L:
for y in convert(x):
yield y
这个递归很难写?不过估计Python除了递归应该有更好的方法吧,我也不太懂。顺带帮你把所有的坐标从序列改成元组格式了。仅供参考:
#!/usr/bin/env python3
def transform(el, args):
return (el[0]*args[0], el[1]*args[0])
def miterator(arrs, mapper, *args):
if isinstance(arrs[0],int):
return mapper(arrs, args[0])
arr = [];
for el in arrs:
if isinstance(el[0], int): item = mapper(el, args[0])
else: item = miterator(el, mapper, args)
arr.append(item)
return arr
coordinates = [[[119,35],[119,35]],[[119,35],[119,35]]]
print(miterator(coordinates, transform, 100))
# [[(11900, 3500), (11900, 3500)], [(11900, 3500), (11900, 3500)]]