Difference between revisions of "MAPREDUCE Elite"
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</div> | </div> | ||
| − | <div class=q data-lang="py3"> | + | <div class=q data-lang="py3">Each system has an <code>allegiance</code>. There are three main factions: <b>The Federation</b>, <b>The Empire</b>, and <b>The Alliance</b>.<br/> |
| − | < | + | <b>The Alliance</b> consists of independent systems, though an independent system is not necessarily part of <b>The Alliance</b>. In such a case their allegiance will be stored as "<b>Independent</b>"<br/> |
| − | < | + | There are a few systems that come under <b>Anarchy</b>. Non-populated systems without stations do not have an allegiance, and should be ignored. |
| − | + | <p class="strong>Show the amount of systems following each type of allegiance.</p> | |
| − | </ | ||
<pre class=def> | <pre class=def> | ||
</pre> | </pre> | ||
<div class="ans"> | <div class="ans"> | ||
| − | temp = db.systems.map_reduce( query={" | + | temp = db.systems.map_reduce( query={"allegiance": {"$ne":None}}, map=Code("function(){emit(this.allegiance, 1)}"), reduce=Code("""function(key,values){var total = 0;values.forEach(function(value){total += value;});return total;} """), out={"inline":1} );pp.pprint(temp['results']) |
</div> | </div> | ||
</div> | </div> | ||
| − | <div class=q data-lang="py3" | + | <div class=q data-lang="py3"> |
| − | + | <p class="strong">What are the populations of the three main factions?</p> | |
| − | |||
| − | <p class="strong> | ||
<pre class=def> | <pre class=def> | ||
</pre> | </pre> | ||
<div class="ans"> | <div class="ans"> | ||
| − | temp = db.systems.map_reduce( query={"allegiance": {"$ | + | temp = db.systems.map_reduce(query={"allegiance":{"$in":["Alliance","Empire","Federation"]}}, map=Code("function(){emit(this.allegiance,this.population)}"), reduce=Code("""function(key,values){var total = 0;values.forEach(function(value){total += value;});return total;} """), out={"inline":1} );pp.pprint(temp['results']) |
</div> | </div> | ||
</div> | </div> | ||
Revision as of 16:13, 25 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.elite.authenticate('scott','tiger')
db = client['elite']
#PRETTY
import pprint
pp = pprint.PrettyPrinter(indent=4)
#JS
from bson.code import Code
Introducing the elite database **WORK IN PROGRESS
These questions will introduce the "elite" database, which contains data about the video game Elite Dangerous
There are two collections, commodities and systems. Inside systems there is are nested documents called stations
A system has many stations, and a station has many trade listings
Keys used in this database.
commodities:
_id, average_price, category, name
systems:
_id, allegiance, faction, government, name, population, primary_economy, security, state, stations, updated_at, x, y, z
systems.stations:
allegiance, distance_to_star, economies, export_commodities,has_blackmarket, has_commodities, has_rearm, has_repair,
has_shipyard, has_outfitting, faction, government, listings, max_landing_pad, name, state, type, updated_at
systems.stations.listings:
buy_price, collected_at, demand, commodity, sell_price, supply, update_count
Read more about the structure here: Elite Document Structure
Questions
commodities collection contains the name and average_price of each commodity.There are 99 unique commodities and 15 categories.
Find the average price of each category, round to the nearest whole number
pp.pprint(
db.commodities.find_one()
)
from bson.code import Code;temp = db.commodities.map_reduce( map=Code("function(){emit(this.category,this.average_price)}"), reduce=Code("""function(key,values){var total = 0;for (var i = 0; i < values.length; i++){total += values[i];}return Math.round(total/values.length);} """),out={"inline":1} );pp.pprint(temp['results'])
allegiance. There are three main factions: The Federation, The Empire, and The Alliance.The Alliance consists of independent systems, though an independent system is not necessarily part of The Alliance. In such a case their allegiance will be stored as "Independent"
There are a few systems that come under Anarchy. Non-populated systems without stations do not have an allegiance, and should be ignored.
Show the amount of systems following each type of allegiance.
temp = db.systems.map_reduce( query={"allegiance": {"$ne":None}}, map=Code("function(){emit(this.allegiance, 1)}"), reduce=Code("""function(key,values){var total = 0;values.forEach(function(value){total += value;});return total;} """), out={"inline":1} );pp.pprint(temp['results'])
What are the populations of the three main factions?
temp = db.systems.map_reduce(query={"allegiance":{"$in":["Alliance","Empire","Federation"]}}, map=Code("function(){emit(this.allegiance,this.population)}"), reduce=Code("""function(key,values){var total = 0;values.forEach(function(value){total += value;});return total;} """), out={"inline":1} );pp.pprint(temp['results'])
Harder Questions
power_control_faction or Power is an individual or organisation who is in control of a system.These powers have allegiances, but the systems they control do not nescessarily have the same allegiance as they do.
Example: At the time of writing Zemina Torval is allied with the Empire and controls 47 systems.
39 are allied to The Empire
3 are allied to The Federation
5 systems are Independent
Long live the Emperor!
'Arissa Lavigny-Duval','Aisling Duval','Denton Patreus' and 'Zemina Torval' all support the empire, show the amount of systems they control that aren't allied to the Empire.
temp = db.systems.map_reduce( query={"power_control_faction":{"$in":['Arissa Lavigny-Duval','Aisling Duval','Denton Patreus','Zemina Torval']},"allegiance":{"$ne":"Empire"}}, map=Code("""function(){ emit({"power_control_faction":this.power_control_faction,"allegiance":this.allegiance},1) }"""), reduce=Code("""function(k,vs){var t = 0;vs.forEach(function(v){t += v});return t} """), out={"inline":1} ); pp.pprint(temp['results']);