Doing our share of data validation
In our Nobel prizes collection, each document has an array of laureate subdocuments "laureates", each containing information such as the prize share for a laureate:
{'_id': ObjectId('5bc56145f35b634065ba1997'),
'category': 'chemistry',
'laureates': [{'firstname': 'Frances H.',
'id': '963',
'motivation': '"for the directed evolution of enzymes"',
'share': '2',
'surname': 'Arnold'},
{'firstname': 'George P.',
'id': '964',
'motivation': '"for the phage display of peptides and antibodies"',
'share': '4',
'surname': 'Smith'},
{...
Each "laureates.share" value appears to be the reciprocal of a laureate's fractional share of that prize, encoded as a string. For example, a laureate "share" of "4" means that this laureate received a \(\frac{1}{4}\) share of the prize. Let's check that for each prize, all the shares of all the laureates add up to 1!
Notice the quotes around the values in the "share" field: these values are actually given as strings! You'll have to convert then to numbers before you find the reciprocals and add up the shares.
Este exercício faz parte do curso
Introduction to MongoDB in Python
Instruções do exercício
- Save a list of prizes (
prizes), projecting out only the"laureates.share"values for each prize. - For each prize, compute the total share as follows:
- Initialize the variable
total_shareto 0. - Iterate over the laureates for each prize, converting the
"share"field of the"laureate"tofloatand adding the reciprocal of it (that is, 1 divided by it) tototal_share.
- Initialize the variable
Exercício interativo prático
Experimente este exercício completando este código de exemplo.
# Save documents, projecting out laureates share
prizes = db.prizes.find({}, [____])
# Iterate over prizes
for prize in ____:
# Initialize total share
total_share = ____
# Iterate over laureates for the prize
for laureate in prize["laureates"]:
# add the share of the laureate to total_share
total_share += ____ / float(____)
# Print the total share
print(total_share)