Question

i have the following code:

import psycopg2
import pylab


class Datenanzeige:

def __init__(self):
    self.conn = psycopg2.connect("dbname='test' user='test' host='test' password='test'")
    self.cur = self.conn.cursor()

    self.site = ['FFF', 'PPP', 'DDD', 'KKK']
    self.plant = [1, 2, 3, 4, 5, 6]


def anzeige(self):

    for i in range(4):
        for j in range(6):

            self.datProd1 = []
            self.datProd2 = []

            self.cur.execute(""" 
                    SELECT proddate, Sum(mods) AS Summevonmods 
                    FROM "20091229global" 
                    GROUP BY proddate, site, plant, pid 
                    HAVING proddate > Date('today') - 14
                    AND
                    site='"""+self.site[i]+"""'
                    AND
                    pid=802
                    AND
                    plant='"""+str(self.plant[j])+"""' 
                    ORDER BY proddate, site, plant, pid; 
                    """)

            self.row = self.cur.fetchone()

            while self.row:
                self.datProd1.append(self.row[0])
                self.datProd2.append(self.row[1])

                pylab.title('Progress of %s' %self.site[i])
                pylab.ylabel('number')
                pylab.xlabel('date')
                pylab.plot(self.datProd1, self.datProd2)
                pylab.savefig("bild%i" %i )

                self.row=self.cur.fetchone()

q = Datenanzeige()
q.anzeige()

the code is working. i get for every self.site variable another picture but every following picture includes the lines of the former one. how can i prevent this?
i need separate pictures without lines of the former one.

Answer 1

To do what you want, you need do one of two things:

1. use the clf() and cla() (clear figure and clear axes respectively) methods after you’ve saved your figures.

2. Create multiple figures, and then set the title and axes label on each figure. At the moment, you’re using a default background figure that pylab gives you. You need to explicitly create and modify different ones. I can’t write the exact code of the top of my head to do that, but a look at the matplotlib api should give you what you are looking for. It will look something like this:

   import matplotlib.pyplot as plt
   
   fig = plt.figure()
   axes = fig.add_subplot(1,1,1)
   axes.set_xlabel("foo")
   axes.set_ylabel("bar")
   axes.set_title("title")
   # ...
   fig.savefig("filename")