Plot a curve to a set of points in python

Question

I have

x_data = [3, 6, 9, 12, 16, 21, 28, 50]

and

y_data = [0, 333.33333333, 333.33333333, 333.33333333, 250, 200, 142.85714286, 45.45454545]

I have attached a graph of what this looks like:

I need to fit this to a curve with function: f(x) = a * exp(-x / b) + c.

However I can't get scipy curve_fit to work. How can I go about this?

Answer 1

You have to define the function you want to fit and then pass it to curve_fit . Your function must take the independent variable first and all the remaining parameters after that.

def func(x, a, b, c):
    return a * np.exp(-x / b) + c

# Get parameters and covariance 
params, cov = scipy.optimize.curve_fit(f=f, xdata=x_data, ydata=y_data)

# Declare dedicated letters for each parameter
a, b, c = params

# Plot
plt.plot(x_data, y_data)
plt.plot(x_data, [func(x, a=a, b=b, c=c) for x in x_data])
plt.show()