Difference between revisions of "FIND from WORLD"
| Line 34: | Line 34: | ||
<div class=ans> | <div class=ans> | ||
pp.pprint(list(db.world.find({},{"name":1,"continent":1,"population":1,"_id":0}))) | pp.pprint(list(db.world.find({},{"name":1,"continent":1,"population":1,"_id":0}))) | ||
| + | </div> | ||
| + | </div> | ||
| + | |||
| + | |||
| + | <div class=q data-lang="py3"> | ||
| + | <p class=strong>Show the name for the countries that have a population of at least 200 million. 200 million is 200000000, there are eight zeros.</p> | ||
| + | <pre class=def> | ||
| + | pp.pprint(list( | ||
| + | db.world.find( | ||
| + | {"population":{"$gt":250000000}}, | ||
| + | {"name":1, "_id":0} | ||
| + | ) | ||
| + | )) | ||
| + | </pre> | ||
| + | <div class=ans> | ||
| + | pp.pprint(list(db.world.find({"population":{"$gt":200000000}},{"name":1, "_id":0}))) | ||
| + | </div> | ||
| + | </div> | ||
| + | |||
| + | <div class=q data-lang="py3"> | ||
| + | <p class=strong>Give the name and the per capita GDP for those countries with a population of at least 200 million.</p> | ||
| + | [[AGGREGATE examples]] are available. | ||
| + | <div class="hint" title="How to calculate per capita GDP">per capita GDP is the GDP divided by the population GDP/population</div> | ||
| + | <pre class=def> | ||
| + | </pre> | ||
| + | <div class=ans> | ||
| + | pp.pprint(list(db.world.aggregate([{"$match":{"population":{"$gt":200000000}}},{"$project":{"name":1, "gdp/population":{"$divide":["$gdp","$population"]}, "_id":0}}]))) | ||
| + | </div> | ||
| + | </div> | ||
| + | |||
| + | <div class=q data-lang="py3"> | ||
| + | <p class=strong>Show the name and population in millions for the countries of the continent 'South America'. Divide the population by 1000000 to get population in millions.</p> | ||
| + | <pre class=def> | ||
| + | </pre> | ||
| + | <div class=ans> | ||
| + | pp.pprint(list(db.world.aggregate([{"$match":{"continent":{"$eq":"South America"}}},{"$project":{"name":1, "population in millions":{"$divide":["$population",1000000]}, "_id":0}}]))) | ||
| + | </div> | ||
| + | </div> | ||
| + | |||
| + | <div class=q data-lang="py3"> | ||
| + | <p class=strong>Show the name and population for France, Germany, Italy</p> | ||
| + | <pre class=def> | ||
| + | </pre> | ||
| + | <div class=ans> | ||
| + | pp.pprint(list(db.world.aggregate([{"$match":{"name":{"$in":["France", "Germany", "Italy"]}}},{"$project":{"name":1, "population":1, "_id":0}}]))) | ||
| + | </div> | ||
| + | </div> | ||
| + | |||
| + | <div class=q data-lang="py3"> | ||
| + | <p class=strong>Show the countries which have a name that includes the word 'United'</p> | ||
| + | <pre class=def> | ||
| + | </pre> | ||
| + | <div class=ans> | ||
| + | pp.pprint(list(db.world.find({"name":{"$regex":"\s?United\s?"}},{"name":1, "_id":0}))) | ||
| + | </div> | ||
| + | </div> | ||
| + | |||
| + | <div class=q data-lang="py3"> | ||
| + | Two ways to be big: A country is big if it has an area of more than 3 million sq km or it has a population of more than 250 million. | ||
| + | |||
| + | |||
| + | <p class=strong>Show the countries that are big by area or big by population. Show name, population and area</p> | ||
| + | <pre class=def> | ||
| + | </pre> | ||
| + | <div class=ans> | ||
| + | pp.pprint(list(db.world.find({"$or":[{"area":{"$gt":3000000}},{"population":{"$gt":250000000}}]},{"name":1,"population":1,"area":1,"_id":0}))) | ||
</div> | </div> | ||
</div> | </div> | ||
Revision as of 17:16, 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.
Observe the result of running a simple mongoDB command.
FIND name, continent, population FROM world
pp.pprint(list(
db.world.find({},{
"name":1,
"continent":1,
"population":1,
"_id":0
})
))
pp.pprint(list(db.world.find({},{"name":1,"continent":1,"population":1,"_id":0})))
Show the name for the countries that have a population of at least 200 million. 200 million is 200000000, there are eight zeros.
pp.pprint(list(
db.world.find(
{"population":{"$gt":250000000}},
{"name":1, "_id":0}
)
))
pp.pprint(list(db.world.find({"population":{"$gt":200000000}},{"name":1, "_id":0})))
Give the name and the per capita GDP for those countries with a population of at least 200 million.
AGGREGATE examples are available.
pp.pprint(list(db.world.aggregate([{"$match":{"population":{"$gt":200000000}}},{"$project":{"name":1, "gdp/population":{"$divide":["$gdp","$population"]}, "_id":0}}])))
Show the name and population in millions for the countries of the continent 'South America'. Divide the population by 1000000 to get population in millions.
pp.pprint(list(db.world.aggregate([{"$match":{"continent":{"$eq":"South America"}}},{"$project":{"name":1, "population in millions":{"$divide":["$population",1000000]}, "_id":0}}])))
Show the name and population for France, Germany, Italy
pp.pprint(list(db.world.aggregate([{"$match":{"name":{"$in":["France", "Germany", "Italy"]}}},{"$project":{"name":1, "population":1, "_id":0}}])))
Show the countries which have a name that includes the word 'United'
pp.pprint(list(db.world.find({"name":{"$regex":"\s?United\s?"}},{"name":1, "_id":0})))
Two ways to be big: A country is big if it has an area of more than 3 million sq km or it has a population of more than 250 million.
Show the countries that are big by area or big by population. Show name, population and area
pp.pprint(list(db.world.find({"$or":[{"area":{"$gt":3000000}},{"population":{"$gt":250000000}}]},{"name":1,"population":1,"area":1,"_id":0})))