title: Form a loop for (i, j, k) where i,j and k lies in [0,5] in R 3.4.4 version
body: <p>The output am trying for is to make a loop of (i, j, k) where i and k takes values [0, 5] and j from [0, 3]. The loop would run on values like:</p>
  
  <pre><code>(0, 0, 0)
  (0, 0, 1)
  (0, 0, 2)
  (0, 0, 3)
  (0, 0, 4)
  (0, 0, 5)
  (0, 1, 0)
  (0, 1, 1)
  (0, 1, 2)
  .
  .
  .
  (5, 3, 5)
  </code></pre>
  
  <p>Basically I want to run arima (p, d, q) model making loop and extract RMSE value from there.</p>
  
  <p>The code for arima I tried is,</p>
  
  <pre><code>fit &lt;- arima(df.train$Positive, order=c(0, 0, 0),include.mean = FALSE)
  S &lt;- as.data.frame(summary(fit))
  S$RMSE
  </code></pre>
  
  <p>The "S$RMSE" gives the RMSE value. 
  But help me in running the loop of "order= c(i, j, k)" and get this RMSE value automatically.</p>
  
  <p>The result I want is finally cbind these two and make a table like,</p>
  
  <pre><code>Order      RMSE
  (0, 0, 0)  xxxx
  (0, 0, 1)  xxxx
  (0, 0 ,2)  xxxx
  </code></pre>