Why isn't my histogram showing on Jupyter notebook?

Question

So I'm relatively new to coding and have recently taken the monstrous task of building a few climate models for my MSc thesis. Using this code I have adapted it and it now shows no error messages except now it doesn't show any figure as an output. Any solutions?

I input

%matplotlib notebook at the top of the code, and also put plt.show(); at the bottom of the script (as per some recommendations through some similar queries)... but still doesn't work. Prior to this it was showing <Figure Ssize 432x288 with 0 Axes> which i presumed may be the problem but i can't figure out why there are 0 axes?

Any recommendations/solutions?

Thanks!

As requested - my code:

import iris.quickplot as qplt
import iris.analysis.cartography
import matplotlib.dates as mdates

def main():
    Current45 = '....X.nc'

    Current45 = iris.load_cube(Current45)

    lats = iris.coords.DimCoord(Current45.coords()[1].points[:,0], \
                                standard_name='latitude', units='degrees')
    lons = Current45.coords()[2].points[0]
    for i in range(len(lons)):
        if lons[i]>100.:
            lons[i] = lons[i]-360.
    lons = iris.coords.DimCoord(lons, \
                                standard_name='longitude', units='degrees')
    Current45.remove_coord('latitude')
    Current45.remove_coord('longitude')
    Current45.add_dim_coord(lats, 1)
    Current45.add_dim_coord(lons, 2)

    Current45.convert_units('Celsius') 

    Colombia = iris.Constraint(longitude=lambda v: -74.73 <= v <= -76.20, \
                               latitude=lambda v: 5.30 <= v <= 4.43) 

    Current45 = Current45.extract(Colombia) 

    iriscc.add_day_of_year(Current45, 'time') 

    Current45.coord('latitude').guess_bounds()
    Current45.coord('longitude').guess_bounds()

    Current45_grid_areas = iris.analysis.cartography.area_weights(Current45)

    Current45 = Current45.collapsed(['latitude', 'longitude'],
                                               iris.analysis.MEAN,
                                               
    weights=Current45_grid_areas)    

    Histogram = Current45.data

    #frq, bins, patches = plt.hist(Histogram, bins=np.arange(20,37,2))
    frq, bins, patches = plt.hist(Histogram, bins=np.arange(16,45,2), color='blue')
    print (frq)


    thresh = 32
    plt.axvline(x=thresh, color='green', linestyle='dashed', linewidth=2)      

    plt.xlabel("Daily Max Temperature / Celsius")
    plt.ylabel("Number of days")

fig = plt.gcf()
plt.show();

My code with blank figure at the bottom

Answer 1

In the code, you are never calling the main function, so the figure you are showing is empty.

You should call main() at some point in your code before the plt.gcf() or plt.show.

Edit

In more detail:

You are writing your main() function in this snippet of code, and then, without indent, you are calling pyplot to get the current figure, where pyplot just gives you en empty figure back (the gcf()-call is not necessary anyways in your code) and plt.show() shows no an empty figure.

You can or cannot move the plt.show() into you main() function, but at one point you must definitely call that function otherwise none of it is executed.

Edit 2:

# function definition
def main():
    ...

# function call
main()

# show figure
plt.show()