[Tutor] using SQLite with matplotlib - queries vs. lists

[Kent Johnson]

Pine Marten wrote:
> I'm a novice hoping to use data stored in an SQLite database to make simple 
> graphs using matplotlib embedded in a wxPython GUI.  I noticed that 
> matplotlib uses lists of integers to make graphs, such as the simple example 
> (from the tutorial) of:
> 
> from pylab import *
> plot([1,2,3,4])
> show()
> 
> But SQLite queries return as a list of tuples in rows, not a list of 
> numbers.  For some reason I haven't found a way any ready-made converter for 
> this purpose.  As an exercise, I've wrote this function that converts them:
> 
> #takes the result of a fetchall() in sql and returns it as a list of numbers
> #assumes you've done the query first, i.e. cur.execute('SELECT * FROM 
> table')
> import sqlite3
> import string
> def query_to_list():
>     queryresult = cur.fetchall()
>     print "Queryresult is ", queryresult
>     queryrows = []
>     for tuple in queryresult:
>         num = tuple[0]
>         queryrows.append(num)
>     querylist = []
>     for row in queryrows:
>         num = int(row)
>         querylist.append(num)
>     print "Query list is: ", querylist

This whole function can be replaced with
     querylist = [ int(row[0]) for rowin cur.fetchall() ]

PS Don't use tuple as a variable name, you will shadow the built-in tuple.

Kent

> 
> My question is, is there a better way to do this, or is there a ready-made 
> way to go from an sql database to matplotlib?  I tried searching for it in 
> various ways but haven't found anything.  I feel as though there should be a 
> more direct way to go from a db to a plot.
> 
> Thanks in advance,
> Chae
> 
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