title: Gurobi Optimization Result Writing into Csv file
body: <p>I am using Gurobi 7 to solve my MIP. I have several different variables. However, I am specifically interested in two of those, "x" and "y" namely. For the reference, I am giving my code that shows how I added x and y variables into the solver:</p>
  
  <pre><code># Creating Variables
  x = {}
  y = {}
  
  # Adding Variables
  for i in range(I):
      x[i+1,P[i]-d[0]] = m.addVar(vtype=GRB.BINARY, name="x%s" % str([i+1,P[i]-d[0]]))
      x[i+1,P[i]] = m.addVar(vtype=GRB.BINARY, name="x%s" % str([i+1,P[i]]))
  for i in range(I):
      for k in range(len(rangevalue)):
          y[i+1, rangevalue[k] - E[i]] = m.addVar(vtype=GRB.BINARY,
                                 name="y%s" % str([i+1, rangevalue[k] - E[i]]))
  </code></pre>
  
  <p>Even though the above code may not really make any sense, I just wanted to show it in case you may use it for my problem.</p>
  
  <p>After I solve the problem, I get the following results:</p>
  
  <p><code>m.printAttr('X')</code></p>
  
  <pre><code>    Variable            X 
  -------------------------
       x[1, 3]            1 
  sigmaminus[1]          874 
       x[2, 2]            1 
  sigmaminus[2]         1010 
       x[3, 2]            1 
  sigmaminus[3]         1945 
       x[4, 4]            1 
  sigmaplus[4]           75 
       x[5, 4]            1 
  sigmaminus[5]         1153 
       x[6, 5]            1 
  sigmaminus[6]          280 
       x[7, 3]            1 
  sigmaplus[7]         1138 
       x[8, 2]            1 
  sigmaplus[8]          538 
       x[9, 1]            1 
  sigmaplus[9]         2432 
      x[10, 5]            1 
  sigmaminus[10]          480 
      omega[1]           12 
      OMEGA[1]           12 
      omega[2]            9 
      OMEGA[2]           12 
      omega[3]            8 
      OMEGA[3]            9 
      omega[4]            8 
      OMEGA[4]            8 
      OMEGA[5]            8 
       y[1, 2]            1 
       y[2, 9]            1 
       y[3, 5]            1 
       y[4, 6]            1 
       y[5, 4]            1 
       y[6, 6]            1 
       y[7, 3]            1 
      y[8, 11]            1 
       y[9, 8]            1 
      y[10, 1]            1 
    phiplus[6]            1 
   phiminus[7]            1 
  phiminus[10]            1 
  </code></pre>
  
  <p>I specifically want to display x and y variables with their indexes. Other variables are not necessary. My question is how can I write these results into an csv file on one column as following?</p>
  
  <pre><code>x[1,3]
  x[2,2]
  x[3,2]
  .
  .
  .
  x[10,5]
  y[1,2]
  y[2,9]
  y[3,5]
  .
  .
  .
  y[10,1]
  </code></pre>
  
  <p>I do not need their corresponding value which can only be "1" since they are binary variables. I just need to write the variables which have the value "1".</p>