提问人：WhiteToggled 提问时间：11/6/2022 更新时间：11/14/2022 访问量：84
如何识别序列方程 Python
how do I identify sequence equation Python
问：
我是否能够识别顺序，但不能识别公式
我有完整的代码
def analyse_sequence_type(y:list[int]):
if len(y) >= 5:
res = {"linear":[],"quadratic":[],"exponential":[],"cubic":[]}
for i in reversed(range(len(y))):
if i-2>=0 and (y[i] + y[i-2] == 2*y[i-1]): res["linear"].append(True)
elif i-3>=0 and (y[i] - 2*y[i-1] + y[i-2] == y[i-1] - 2*y[i-2] + y[i-3]): res["quadratic"].append(True)
for k, v in res.items():
if v:
if k == "linear" and len(v)+2 == len(y): return k
elif k == "quadratic" and len(v)+3 == len(y): return k
return
print(f"A relation cannot be made with just {len(y)} values.\nPlease enter a minimum of 5 values!")
return
我可以识别，但是我如何制作一个函数linearquadratic
答：
1赞
The Myth
11/6/2022
#1
因此，首先我们需要为 and 创建两个函数（公式附在下面）。linearquadratic
def linear(y):
"""
Returns equation in format (str)
y = mx + c
"""
d = y[1]-y[0] # get difference
c = f"{y[0]-d:+}" # get slope
if d == 0: c = y[0] - d # if no difference then intercept is 0
return f"f(x) = {d}x {c} ; f(1) = {y[0]}".replace("0x ","").replace("1x","x").replace(" + 0","");
我们应用类似的逻辑：quadratic
def quadratic(y):
"""
Returns equation in format (str)
y = ax² + bx + c
"""
a = logic_round((y[2] - 2*y[1] + y[0])/2) # get a
b = logic_round(y[1] - y[0] - 3*a) # get b
c = logic_round(y[0]-a-b) # get c
return f"f(x) = {a}x² {b:+}x {c:+} ; f(1) = {y[0]}".replace('1x²','x²').replace('1x','x').replace(' +0x','').replace(' +0','')
如果您尝试使用多个输入的代码，例如您将得到（示例）。要省略该尝试：5.05.0x + 4
def logic_round(num):
splitted = str(num).split('.') # split decimal
if len(splitted)>1 and len(set(splitted[-1])) == 1 and splitted[-1].startswith('0'): return int(splitted[0]) # check if it is int.0 or similar
elif len(splitted)>1: return float(num) # else returns float
return int(num)
上述函数将以任何方式工作，前提是 是域所在的列表。y[1, ∞)
希望这对:)有所帮助也试试立方体。
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