如何确定参数是否为数字列表？ （蟒蛇）

Question

I've been working on Bézier curve and I got everything working fine, but I want to make sure user will enter proper input.

I need statement checking if entered value is a list containing exactly two numbers, let it be integers or floats. More info is always welcome.

If anyone needs the code, here you go. (There's probably just a formula for it somewhere, and this here is inefficient. ^^)

#finding a point on vector based on start point, end and %
def findPoint(t, A, B):
    '''
    findPoint( 'float member of <0, 1>',
               'coordinates of point A written as [x, y]',
               'coordinates of point B written as [x, y]')
    '''
    x=(B[0]-A[0])*t+A[0]
    y=(B[1]-A[1])*t+A[1]
    return [x, y]

#find coordinates of a point on the bezier curve
def bezierCurve(t, *points):
    pointList=[]
    for X in points:
        pointList.append(X)
    while len(pointList) !=1:
        tempList=[]
        for i in xrange(0, len(pointList)-1):
            tempList.append(findPoint(t, pointList[i], pointList[i+1]))
        pointList=tempList
return pointList.pop()

Answer 1

You could check that all of the elements are int (or float ) by using all

>>> l = [1,2,3]
>>> a = ['a','b','c']
>>> all(isinstance(i, int) for i in l)
True
>>> all(isinstance(i, int) for i in a)
False

Also you could check that len(list) == 2

So as a function it could be something like

def twoNumValues(myList):
    return len(myList) == 2 and all(isinstance(i, int) or isinstance(i, float) for i in myList)

Or

def twoNumValues(myList):
    return len(myList) == 2 and all(type(i) in [float, int] for i in myList)

Answer 2

This is a one line function to test the parameters you describe:

def check(l):
    return len(l) == 2 and all(type(i) in (int, float) for i in l)

First check that the length is exactly 2, then check that both (all) of them are either int or float.