How to plot an histogram from a dictionary data?
you can try this way:

dictonary = {'1': {'1': 2.5039}, '2': {'2': 8.993242, '1': 8.972473}, '7': {'5': 6.4600, '7': 9.16026}, '3': {'5': 6.46004, '3': 8.8472, '6': 8.8266, '1': 8.806035}, '5': {'5': 8.70111}, '6': {'6': 8.8889}, '4': {'4': 9.55662}}
new_dictonary = {str((k,k1)):v1 for k, v in dictonary.items() for k1,v1 in v.items()}
plt.figure(figsize=(15,5))
plt.bar(new_dictonary.keys(), new_dictonary.values(), width=.5, color='g')