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def between(beg, end, mid):
return end > mid >= beg or end < mid <= beg
def get_slice(a, beg, end, delta = 1):
if delta == 0:
raise ValueError("slice step cannot be 0")
if beg < 0:
beg += len(a)
if end < 0:
end += len(a)
if beg < 0 and end < 0 or beg >= len(a) and end >= len(a):
print("begin都小于0 或 长度都越界")
return []
if(end - beg) * delta <= 0:
print("end - beg 与 delta 的方向不相同")
return []
beg = max(0, min(beg, len(a) - 1))
end = max(-1, min(end, len(a)))
ans = []
i = beg
print("beg:%d, end:%d, delta:%d"%(beg, end, delta))
while between(beg, end, i):
ans.append(i)
i += delta
return ans
def test_getslice():
import random
a = list(range(10))
for i in range(10):
beg = random.randint(-15, 15)
end = random.randint(-15, 15)
delta = 0
while delta == 0:
delta = random.randint(-15, 15)
print("a:", a)
print("beg:%d,end:%d,delta:%d"%(beg, end, delta))
ans = get_slice(a, beg, end, delta)
print("get_slice(a, beg, end, delta):", ans)
print("a[beg:end:delta]:", a[beg:end:delta])
print(len(ans) == len(a[beg:end:delta]))
print("")
test_getslice()
"""
def between(beg, end, mid):
# 判断mid是否位于begin和end之间
return end > mid >= beg or end < mid <= beg
def get_slice(a, beg, end, delta=1):
# 数组切片get方式
if delta == 0: raise ValueError("slice step cannot be 0")
# 将负数下标转化一下
if beg < 0: beg += len(a)
if end < 0: end += len(a)
# 如果转化完成之后依然不在合法范围内，则返回空列表
if beg < 0 and end < 0 or beg >= len(a) and end >= len(a): return []
# 如果方向不同，则返回空列表
if (end - beg) * delta <= 0: return []
# 将越界的部分进行裁剪
beg = max(0, min(beg, len(a) - 1))
end = max(-1, min(end, len(a)))
ans = []
i = beg
while between(beg, end, i):
ans.append(a[i])
i += delta
return ans
def set_slice(a, li, beg, end, delta=1):
if delta == 0: raise ValueError("slice step cannot be 0")
if delta == 1:
# 如果delta==1，那么li的长度可以随意
if beg < 0: beg += len(a)
if end < 0: end += len(a)
beg = max(0, min(beg, len(a) - 1))
end = max(-1, min(end, len(a)))
for i in range(beg, end):
del a[beg]
for i in reversed(li):
a.insert(beg, i)
else:
# delta!=1,相当于替换
if len(get_slice(a, beg, end, delta)) != len(li): raise ValueError("array don't match")
if len(li) == 0: return
if beg < 0: beg += len(a)
if end < 0: end += len(a)
beg = max(0, min(beg, len(a) - 1))
# 用li中的全部元素逐一替换
for ind, value in enumerate(li):
a[ind * delta + beg] = value
def test_getSlice():
a = list(range(10))
import random
for i in range(10):
beg = random.randint(-15, 15)
end = random.randint(-15, 15)
delta = 0
while delta == 0: delta = random.randint(-15, 15)
print(len(get_slice(a, beg, end, delta)) == len(a[beg:end:delta]), beg, end, delta)
def test_setSlice():
import random
for i in range(10):
a = list(range(10))
beg = random.randint(-15, 15)
end = random.randint(-15, 15)
delta = 0
while delta == 0: delta = random.randint(-5, 5)
sz = len(a[beg:end:delta])
if delta == 1: sz = random.randint(0, 4)
li = [random.randint(0, 100) for i in range(sz)]
set_slice(a, li, beg, end, delta)
mine = a
a = list(range(10))
a[beg:end:delta] = li
print(a == mine)
test_setSlice()
"""
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