Difference between revisions of "FIND basics"
| Line 1: | Line 1: | ||
| + | #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 <code>world</code> collection of countries== | ==Working with the <code>world</code> collection of countries== | ||
Revision as of 10:35, 28 July 2015
- 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
This tutorial introduces NoSQL using MonogDB and PyMongo under Python3.4. We will be using the find() command and comparison functions on the collection world which contains details of around 250 countries of the world:
FIND examples are available.
Use find() to return the 21st document in world
Show the 21st document in world
pp.pprint(
db.world.find()[0]
)
pp.pprint(db.world.find()[20])
List all the countries in the continent of Asia
pp.pprint(list(
db.world.find({},{"capital":1, "_id":0})
))
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)))
Use Sort to find the last document in world
Show the last document of world
pp.pprint(list(db.world.find().sort("$natural", -1))[0])
Show capital and population for the top 5 capital cities starting with the letter "M" that have a population of less than 3 million
pp.pprint(list(db.world.find({"$and":[{"capital":{"$regex":"^M"}},{"population":{"$lt":3000000}}]}, {"_id":0, "capital":1, "population":1}).sort("population",-1).limit(5)))