title: Python Pandas plot. Script does not see a numeric value in text file
body: <p>I have a script that queries data from a database. It then exports it to a CSV file. The goal is to create a plot with the numeric data in the column. But the script does not see any numerical values in the column specified.</p>
  
  <pre><code>import pandas.io.data
  import matplotlib.pyplot as plt
  import pandas as pd
  from pandas import DataFrame
  import datetime
  import pandas.io.data
  import psycopg2
  import csv
  import pandas.io.data
  
  conn = psycopg2.connect("host='172.31.98.161' dbname='servers' user='seeker'")
  cur = conn.cursor() #Create the cursor
  cur.execute("select hostname, used_ram_raw from server_perf  where                 hostname='localhost.localdomain'")
  rows = cur.fetchall()
  conn.close()
  
  df = pd.DataFrame(rows, columns=['One','Two'])
  df.to_csv("file.csv")
  df = df.convert_objects(convert_numeric=True)    
  df[['Two']].plot()
  plt.show()
  </code></pre>
  
  <p>The above script produces the following file called "file.csv"</p>
  
  <pre><code>,One,Two
  0,localhost.localdomain,1521819648.00
  1,localhost.localdomain,1632538624.00
  2,localhost.localdomain,1633038336.00
  3,localhost.localdomain,1632264192.00
  </code></pre>
  
  <p>The error produced is whn trying to plot is:</p>
  
  <pre><code>TypeError: Empty 'DataFrame': no numeric data to plot
  </code></pre>
  
  <p>Just for testing I did a</p>
  
  <pre><code>  print df[['Two']]
  </code></pre>
  
  <p>and it printed the following</p>
  
  <pre><code>             Two
  0  1521819648.00
  1  1632538624.00
  2  1633038336.00
  3  1632264192.00
  </code></pre>
  
  <p>What am I doing wrong? :(</p>