catch RuntimeError of curve_fit and its description-CodePudding

Sometimes scipy.curve_fit raises a RuntimeError exception.

Example code (explicitly written to raise the exception):

import numpy
from scipy.optimize import curve_fit

def model(x, A, B):
    return A * x   B

data = numpy.array([[0, 1], [1, 2]])
par, cov = curve_fit(model, data[:, 0], data[:, 1], p0 = [0, 0], maxfev=1)

Running the code raises the exception

RuntimeError: Optimal parameters not found: Number of calls to function has reached maxfev = 1.

I can catch the exception with

import numpy
from scipy.optimize import curve_fit

def model(x, A, B):
    return A * x   B

data = numpy.array([[0, 1], [1, 2]])
try:
    par, cov = curve_fit(model, data[:, 0], data[:, 1], p0 = [0, 0], maxfev=1)
except RuntimeError:
    print('Runtime Error!')

How can I retrieve the entire descriptive string of the exception, that is, the error message "Optimal parameters not found: Number of calls to function has reached maxfev = 1"?

CodePudding user response：

import numpy
from scipy.optimize import curve_fit

def model(x, A, B):
    return A * x   B

data = numpy.array([[0, 1], [1, 2]])
try:
    par, cov = curve_fit(model, data[:, 0], data[:, 1], p0 = [0, 0], maxfev=1)
except RuntimeError as e:
    print('Runtime Error :', str(e))

This catches the exception as a variable e and uses a string conversion to get the error info.