CODEWITHSUNDEEP
mysqlweb.py
Nipun Batra
Nipun Batra

Reputation: 11367

Effectively use query results using web.py

I am using web.py for managing my web application and using MySQL as the database. I make a raw query and get the results and i convert it to a list and iterate over it. I need to push the retrieved columns in Arrays (or Numpy arrays) and then plot using Matplotlib. Everything works but i am not sure if the approach i use is most efficient? The code is:

retrieved_data=list(db.query(query))
LEN=len(retrieved_data)
x=[0]*LEN
y=[0]*LEN
X=[None]*LEN
for i in range(0,LEN):
    x[i]=retrieved_data[i]["timestamp"]
    y[i]=retrieved_data[i][parameter]
    X[i]=datetime.datetime.fromtimestamp(x[i],pytz.timezone(TIMEZONE))

Upvotes: 1

Views: 392

Answers (1)

Andrey Kuzmin
Andrey Kuzmin

Reputation: 4479

You don't have to convert the result of db.query if you only need to iterate it once. So your particular example can be a little bit simplified.

x, y, X = [], [], []
for item in db.query(query):
    x.append(item.timestamp)
    y.append(item[parameter])
    X.append(datetime.datetime.fromtimestamp(item.timestamp,
                                             pytz.timezone(TIMEZONE))

Or if you need to iterate many times on the same result, you may use .list() method to convert it into list.

retrieved_data = db.query(query).list()

Upvotes: 2

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