FIND basics
#ENCODING
import io
import sys
sys.stdout = io.TextIOWrapper(sys.stdout.buffer, encoding='utf-16')
#MONGO
from pymongo import MongoClient
client = MongoClient()
client.progzoo.authenticate('scott','tiger')
db = client['progzoo']
#PRETTY
import pprint
pp = pprint.PrettyPrinter(indent=4)
Working with the world collection of countries
These examples introduce NoSQL using MonogDB and PyMongo under Python3.4. We will be using the find() command and basic comparison functions on the collection world:
For help on this click here
Use find() to return the 21st document in world
Show the 21st document in world
pp.pprint(
db.world.find()
)
pp.pprint(db.world.find()[20])
Use sort() to find the last document in world
Show the last document of world
pp.pprint(list(db.world.find().sort("$natural", -1).limit(1)))
List all the countries in the continent of Asia
pp.pprint(list(db.world.find({"continent":"Asia"}, {"_id":0, "name":1})))
How many countries are there in Europe that start with the letter "L"
print(db.world.count({"$and":[{"continent":"Europe"},{"name":{"$regex":"^S"}}]}))
Find the capital cities for countries with a population of over 70 million
pp.pprint(list(db.world.find({"population":{"$gt":70000000}},{"capital":1,"_id":0})))
Find the countries that have a population of over 100 million or less than a million
pp.pprint(list(db.world.find({"$or":[{"population":{"$lt":1000000}},{"population":{"$gt":100000000}}]}, {"name":1, "_id":0})))
Find the names of countries beginning with "U" that are outside of Europe and North America
pp.pprint(list(db.world.find({"$and":[{"name":{'$regex':"^U"}},{"continent":{"$nin":["Europe", "North America"]}}]},{"name":1,"_id":0})))
Find the names of all countries that contain a white space
pp.pprint(list(db.world.find({"name":{"$regex":"^.*\s.*$"}},{"name":1,"_id":0})))
Which country out of [China, Russia, United States] has the largest population
pp.pprint(list(db.world.find({"name":{"$in":["China", "Russia", "United States"]}}).sort("population",-1).limit(1)))
Show the top 5 capitals and populations for capital cities starting with the letter "M" that have a population of less than 3 million
pp.pprint(list(db.world.find({"$and":[{"capital":{"$regex":"^M"}},{"population":{"$lt":3000000}}]}, {"_id":0, "capital":1, "population":1}).sort("population",-1).limit(5)))