I am trying to create f-distributed random numbers with given degree of freedoms d1 and d2, and plot both a histogram with f-distributed random numbers, and plot an idealised f-distribution curve, but when I give small values to df's, the histogram does not show up. I am new at statistics and matplotlib, and I could not figure out how to deal with this problem. This is my code:
def distF(request, distribution_id):
dist = get_object_or_404(Distribution, pk=distribution_id)
dfd = dist.var4
dfn = dist.var2
x = np.random.f(dfn, dfd, size = dist.var3)
num_bins = 50
fig, ax = plt.subplots()
print(x)
# the histogram of the data
n, bins, patches = ax.hist(x, num_bins, normed=True)
y = np.linspace(0, 5, 1001)[1:]
dist = st.f(dfn, dfd, 0)
#y = np.linspace(st.f.ppf(0.01, dfn, dfd), st.f.ppf(0.99, dfn, dfd), 100)
ax.plot(y, dist.pdf(y), '--')
ax.set_xlabel('Smarts')
ax.set_ylabel('Probability density')
ax.set_xlim([0, 4])
ax.set_ylim([0, 3])
fig.tight_layout()
canvas = FigureCanvas(fig)
response = HttpResponse(content_type='image/png')
canvas.print_png(response)
plt.close(fig)
return response
This is how the plots look like:
F-distribution plot with small df values
F-distribution plot with large df values