I have two columns(rcs,range) in a dataframe.

I want to plot a curve with equation rcs = range^4

I tried the following 1.as a polynomial curve fitting

def curve_gen(x,a,b,c,d,e):  #for polynomial
    return (a*(x**4)) (b*(x**3)) (c*(x**2)) (d*x) e

y = df['rcs'].values
x = df['range'].values
pop,_ = curve_fit(curve_gen,x,y)
a,b,c,d,e = pop
pl.scatter(y,x)
pl.plot(curve_gen(x,a,b,c,d,e),x,color = 'red')
pl.show()

in the above plot,the curve is not a smooth curve and is not starting from -40

2.power law curve fit

def power_law(x,a):  
    return a*np.power(x,4)

y = df['rcs'].values
x = df['range'].values
pop,_ = curve_fit(power_law,x,y)
a = pop
pl.scatter(y,x)
pl.plot(power_law(x,a),x,color = 'red')
pl.show()

this one giving me a wrong plot.the red line is not passing through the blue points

how to solve the above issue using curve_fit?and plot

CodePudding user response：

You can use