value error when using 1d array for curve fitting-CodePudding

I am getting this error when using Scipy curve fitting to get the fitting parameters (A,B,C,D). There is no problem with defined function and works well and responds well. There is also no problem when the x (x11, x22) and y array (used for curve fitting) are just one element array and not 1d array with some elements. I know that this problem is because of multi elements in the input array for fitting (x11, x22, y). Actually, I think it is because the code does not know to which element of array should apply the condition in the function. but, I do not how to solve it. Any help and suggestion would be appreciated!

Here is the code:

x11=fin[:,0]
x22=fin[:,1]
y=fin[:,2]

bin=[4,4.5,5,5.5]


def interpo(x,A,B, C, D):
    x1, x2=x
    if  bin[0] <= x1 <bin[1]:
        if np.logical_and(x2>= bin[0] , x2<bin[1]):
            f1=A   ((x1 -bin[0])/(bin[1]-bin[0]))*(B-A)
            f2=A   ((x2 -bin[0])/(bin[1]-bin[0]))*(B-A)
            kh=f2/f1
        if x2>= bin[1] and x2<bin[2]:
            f1=A   ((x1 -bin[0])/(bin[1]-bin[0]))*(B-A)
            f2=B   ((x2 -bin[1])/(bin[2]-bin[1]))*(C-B)
            kh=f2/f1
            
        if x2>= bin[2] and x2<bin[3]:
            f1=A   ((x1 -bin[0])/(bin[1]-bin[0]))*(B-A)
            f2=C   ((x2 -bin[2])/(bin[3]-bin[2]))*(D-C)
            kh=f2/f1
    if x1>= bin[1] and x1<bin[2]:
        if x2>= bin[1] and x2<bin[2]:
            f1=B   ((x1 -bin[1])/(bin[2]-bin[1]))*(C-B)
            f2=B   ((x2 -bin[1])/(bin[2]-bin[1]))*(C-B)
            kh=f2/f1
        if x2>= bin[2] and x2<bin[3]:
            f1=B   ((x1 -bin[1])/(bin[2]-bin[1]))*(C-B)
            f2=C   ((x2 -bin[2])/(bin[3]-bin[2]))*(D-C)
            kh=f2/f1
    if x1>= bin[2] and x1<bin[3]:
        if x2>= bin[2] and x2<bin[3]:
            f1=C   ((x1 -bin[2])/(bin[3]-bin[2]))*(D-C)
            f2=C   ((x2 -bin[2])/(bin[3]-bin[2]))*(D-C)
            kh=f2/f1
            
    return (kh)

popt, pcov = curve_fit(interpo, (x11,x22), y, method='lm')

And here is the error:

      Input In [3] in interpo
    if  bin[0] <= x1 <bin[1]:

ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

CodePudding user response：

Let's try to change the line of code the error complains about from

if bin[0] <= x1 <bin[1]:
    pass

if (x1 >= bin[0]) & (x1 <bin[1]):
    pass

The same for other similar comparisons.

CodePudding user response：

In order to evaluate the values in x one by one, you can use the following function:

def interpo(x, A, B, C, D):
    result = []
    for x1, x2 in zip(x[0], x[1]):
        if  bin[0] <= x1 <bin[1]:
            if np.logical_and(x2>= bin[0] , x2<bin[1]):
                f1=A   ((x1 -bin[0])/(bin[1]-bin[0]))*(B-A)
                f2=A   ((x2 -bin[0])/(bin[1]-bin[0]))*(B-A)
                kh=f2/f1
            if x2>= bin[1] and x2<bin[2]:
                f1=A   ((x1 -bin[0])/(bin[1]-bin[0]))*(B-A)
                f2=B   ((x2 -bin[1])/(bin[2]-bin[1]))*(C-B)
                kh=f2/f1
                
            if x2>= bin[2] and x2<bin[3]:
                f1=A   ((x1 -bin[0])/(bin[1]-bin[0]))*(B-A)
                f2=C   ((x2 -bin[2])/(bin[3]-bin[2]))*(D-C)
                kh=f2/f1
        if x1>= bin[1] and x1<bin[2]:
            if x2>= bin[1] and x2<bin[2]:
                f1=B   ((x1 -bin[1])/(bin[2]-bin[1]))*(C-B)
                f2=B   ((x2 -bin[1])/(bin[2]-bin[1]))*(C-B)
                kh=f2/f1
            if x2>= bin[2] and x2<bin[3]:
                f1=B   ((x1 -bin[1])/(bin[2]-bin[1]))*(C-B)
                f2=C   ((x2 -bin[2])/(bin[3]-bin[2]))*(D-C)
                kh=f2/f1
        if x1>= bin[2] and x1<bin[3]:
            if x2>= bin[2] and x2<bin[3]:
                f1=C   ((x1 -bin[2])/(bin[3]-bin[2]))*(D-C)
                f2=C   ((x2 -bin[2])/(bin[3]-bin[2]))*(D-C)
                kh=f2/f1
        result.append(kh)        
    return result