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As electronic vehicles (EVs) become more popular, there is an increasing need for access to charging stations, also known as ports. To that end, many modern apartment buildings have begun retrofitting their parking garages to include shared charging stations. A charging station is shared if it is accessible by anyone in the building.

But with increasing demand comes competition for these ports — nothing is more frustrating than coming home to find no charging stations available! In this project, you will use a dataset to help apartment building managers better understand their tenants’ EV charging habits.

The data has been loaded into a PostgreSQL database with a table named charging_sessions with the following columns:

charging_sessions

ColumnDefinitionData type
garage_idIdentifier for the garage/buildingVARCHAR
user_idIdentifier for the individual userVARCHAR
user_typeIndicating whether the station is Shared or PrivateVARCHAR
start_pluginThe date and time the session startedDATETIME
start_plugin_hourThe hour (in military time) that the session startedNUMERIC
end_plugoutThe date and time the session endedDATETIME
eng_plugin_hourThe hour (in military time) that the session endedNUMERIC
duration_hoursThe length of the session, in hoursNUMERIC
el_kwhAmount of electricity used (in Kilowatt hours)NUMERIC
month_pluginThe month that the session startedVARCHAR
weekdays_pluginThe day of the week that the session startedVARCHAR

Let’s get started!

Sources
  • Data: CC BY 4.0, via Kaggle,
  • Image: Julian Herzog, CC BY 4.0, via Wikimedia Commons
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DataFrameas
unique_users_per_garage
variable
-- unique_users_per_garage
-- Modify the code below
SELECT 
	garage_id,
	COUNT(DISTINCT user_id) AS num_unique_users
FROM charging_sessions
WHERE user_type = 'Shared'
GROUP BY garage_id
ORDER BY num_unique_users DESC
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DataFrameas
most_popular_shared_start_times
variable
-- most_popular_shared_start_times
SELECT 
	weekdays_plugin,
	start_plugin_hour,
	COUNT(*) AS num_charging_sessions
FROM charging_sessions
WHERE user_type = 'Shared'
GROUP BY weekdays_plugin, start_plugin_hour
ORDER BY num_charging_sessions DESC
LIMIT 10;
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DataFrameas
long_duration_shared_users
variable
-- long_duration_shared_users
SELECT 
	user_id,
	AVG(duration_hours) AS avg_charging_duration
FROM charging_sessions
WHERE user_type = 'Shared'
GROUP BY user_id
HAVING AVG(duration_hours) > 10
ORDER BY avg_charging_duration DESC
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DataFrameas
df
variable
SELECT *
FROM charging_sessions
WHERE (user_type = 'Shared') AND duration_hours = (SELECT MAX(duration_hours) FROM charging_sessions WHERE user_type = 'Shared') OR duration_hours = (SELECT MIN(duration_hours) FROM charging_sessions WHERE user_type = 'Shared')
LIMIT 10
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DataFrameas
df1
variable
WITH shared_F AS 
(SELECT *
FROM charging_sessions
WHERE user_type = 'Shared' AND weekdays_plugin = 'Sunday' )

SELECT garage_id, el_kwh, duration_hours, el_kwh / duration_hours AS calc
FROM shared_F
WHERE (start_plugin_hour BETWEEN 14 AND 18) AND EXTRACT (month from start_plugin) = 12