Matplotlib savefig() 将绘图保存为空白图像

Question

I'm trying to save graphs in folders I'm creating and they all show within Jupyter notebook but save as blank images within my folders. This is my code:

    munilist = ["Adjuntas", "Anasco", "Ciales", "Jayuya", "Lares", "LasMarias", "Maricao", "Mayaguez", "Orocovis", "Penuelas", "Ponce", "SabanaGrande", "SanGerman", "SanSebastian", "Utuado", "Yauco"]
    for municipality in munilist:
        
        x = np.array([1987, 1992, 1998, 2002, 2007, 2012]).reshape(6,1)
        y = np.array(df[df["Municipio"]==municipality].iloc[0, 1:7]).reshape(6,1)
        print(y)
        mask = ~pd.isnull(y) #creating a mask to get rid of NaN columns values in certain csvs
        print(mask)
        xlin = np.arange(1987, 2013,1) #range of years to plot
        reg = LinearRegression(fit_intercept=True).fit(x[mask].reshape(-1,1), y[mask])
        a0 = reg.intercept_
        a1 = reg.coef_[0]

        fit = a0 + a1*xlin #fitted value

        b0 = float(a0) #f strings do not accept array. Need to convert to float
        b1 = float(a1)
        eq = f"$farms = ${b0:.3f} $+$ {b1:.3f}$*year$"

        plt.scatter(x,y, label = name)
        plt.title(municipality)
        plt.plot(xlin, fit, 'r', label = "fitted line")
        plt.xlabel("Year")
        plt.ylabel(name)
        plt.text(2000,1000, eq)
        plt.legend()
        plt.figure(figsize=(3, 3)) #had to change figure size because they were coming out way too large
        if not os.path.isdir("RegressionsOutput/" + municipality):
            os.makedirs("RegressionsOutput/" + municipality)
        plt.savefig("RegressionsOutput/" + municipality + "/" + name + '.png', format="png", dpi=300, bbox_inches = 'tight') #save before showing
        plt.show()

This is what saves in my folders

Answer 1

You're calling plt.figure(figsize=...) after having done all of the work. This will reset the figure. Just move this line to the top so that it looks like

eq = f"..."
plt.figure(figsize=(3,3))
...
plt.savefig(...)

I'm 95% sure this is your problem.

plt.figure() is designed to be used to create a new figure, so you will be overwriting any work you've done.

Answer 2

You should explicitly define the figure (eg "fig") initially (ie prior to plt.scatter()):

fig = plt.figure(figsize=(3, 3), num=1, clear=True)

and then show:

plt.show()

and then save:

fig.savefig("RegressionsOutput/" + municipality + "/" + name + '.png', ...)