title: use logging.info to write float values inside a log file
body: <p>I am using logging package to write some error values and a matrix inside a log file.</p>
  
  <pre><code>logging.info("Error = %.4f"%err)
  logging.info(error_mat) #error_mat is a NxN matrix
  </code></pre>
  
  <p>However, the matrix gets written in a different manner:</p>
  
  <pre><code>2014-09-08 14:10:20,107 - root - INFO - [[  8.30857546   0.69993454   0.20645551  
  77.01797674  13.76705776]
   [  8.35205432   0.53417203   0.19969048  76.78598173  14.12810144]
   [  8.37066492   0.64428449   0.18623849  76.4181809   14.3806312 ]
   [  8.50493296   0.5110043    0.19731849  76.45838604  14.32835821]
   [  8.18900791   0.4955451    0.22524777  76.96966663  14.12053259]]
  </code></pre>
  
  <p>or</p>
  
  <pre><code>2014-09-08 14:12:22,211 - root - INFO - [[  3.25142253e+01   1.11788106e+00   1.51065008e-02   6.16496299e+01
      4.70315726e+00]
   [  3.31685887e+01   9.53522041e-01   1.49767860e-02   6.13449154e+01
      4.51799710e+00]
   [  3.31101827e+01   1.09729703e+00   5.03347259e-03   6.11818594e+01
      4.60562742e+00]
   [  3.32506957e+01   1.13837592e+00   1.51783456e-02   6.08651657e+01
      4.73058437e+00]
   [  3.26809490e+01   1.06617279e+00   1.00110121e-02   6.17429172e+01
      4.49994994e+00]]
  </code></pre>
  
  <p>How can we specify the precision for the float values inside the error_mat, e.g. %.3f for a 3 decimal point precision? Also this will ensure the matrix values to be written in a single without line breaks.</p>