[kwlug-disc] Any Python Experts?

CrankyOldBugger crankyoldbugger at gmail.com
Thu Sep 13 10:19:35 EDT 2018


There is actually Python Users Group in Waterloo.   http://watpy.ca/

I'm sure you'd find an expert in there.  The group leader is Albert
O'Connor.


On 13 September 2018 at 10:15, John Driezen <jdriezen at sympatico.ca> wrote:

>
> I am trying to write a program to plot scrap copper prices using python,
> sqlite3 and plotly.  I have run into a bit of a snag.  The plotly library
> only works with Python 2.7, and I wrote a scraper to work with Python 3.5.
> When I read the data from the sql database using Python 2.7.2 I get an
> unexpected 'u' in front of my date values.  Using the Python 3.5.2
> interpreter produces the correct results.
>
> john at LinuxMint18 ~/scrap_prices_scraper $ cat read_data.py
> import sqlite3
> import os
>
> DB_FILE = '/home/john/scrap_prices_scraper/scrapmetalprices.db'
>
> # check for existing database file
> if os.path.isfile(DB_FILE):
>     connection = sqlite3.connect(DB_FILE)
>
>     cursor = connection.execute ("SELECT * from PRICES WHERE MATERIAL='#1
> Bright Copper'")
>
>     price=[]
>     dates=[]
>     for row in cursor:
>         dates.append(row[4])    # store date in list
>         price.append(row[2])     # store price in list
>         print (dates, price)
>
>     connection.close
> else:
>     print("Database does not exist.")
>
> raise SystemExit
> john at LinuxMint18 ~/scrap_prices_scraper $ python --version
> Python 2.7.12
> john at LinuxMint18 ~/scrap_prices_scraper $ python3 --version
> Python 3.5.2
>
> The incorrect results with the Python 2.7 interpreter:
>
> john at LinuxMint18 ~/scrap_prices_scraper $ python read_data.py
> ([u'2018-08-31'], [3.13])
> ([u'2018-08-31', u'2018-09-04'], [3.13, 3.03])
> ([u'2018-08-31', u'2018-09-04', u'2018-09-10'], [3.13, 3.03, 3.03])
> ([u'2018-08-31', u'2018-09-04', u'2018-09-10', u'2018-09-12'], [3.13,
> 3.03, 3.03, 3.03])
>
> The correct results with the Python3 interpreter:
>
> john at LinuxMint18 ~/scrap_prices_scraper $ python3 read_data.py
> ['2018-08-31'] [3.13]
> ['2018-08-31', '2018-09-04'] [3.13, 3.03]
> ['2018-08-31', '2018-09-04', '2018-09-10'] [3.13, 3.03, 3.03]
> ['2018-08-31', '2018-09-04', '2018-09-10', '2018-09-12'] [3.13, 3.03,
> 3.03, 3.03]
> john at LinuxMint18 ~/scrap_prices_scraper $ exit
> exit
>
> Script done on Thu 13 Sep 2018 09:57:20 AM EDT
>
> Does anyone have any suggestions?
>
> John Driezen
>
>
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