title: Use output results as data for more calculations - R
body: <p>I am totally novel in using R and I am stuck in my analyses. I have used a function to do some calculations with my data. Once I got the results (pasted below) I need to use them again to calculate the mean of the variable "PX" but I do not know how to proceed. I have tried several options but without success. 
  Thanks in advance and sorry for this (probably) vague question.</p>
  
  <pre><code>ndiv &lt;- fitplcs(data,
                  "Sample",
                  varnames=c(PLC="PLC", WP="PSI"),
                  weights=NULL,
                  random =NULL,
                  model= "sigmoidal",
                  x = 50,
                  coverage = 0.95,
                  bootci = TRUE,
                  nboot = 50,
                  quiet = TRUE,
                  startvalues = NULL)
  ndiv
  
  # Group:  PH_1 
      Estimate Boot - 2.5% Boot - 97.5%
  SX 31.649016   20.219422    41.891662
  PX  4.049126    3.813595     4.623607
  
  # Group:  PH_1-Pink 
      Estimate Boot - 2.5% Boot - 97.5%
  SX 27.062688   18.110285    32.795379
  PX  5.430344    5.123864     6.292341
  
  # Group:  PH_1b 
      Estimate Boot - 2.5% Boot - 97.5%
  SX 35.411346   28.955444    43.805794
  PX  4.098899    3.940512     4.394827
  
  # Group:  PH_2 
      Estimate Boot - 2.5% Boot - 97.5%
  SX 40.033074   16.774300    70.725351
  PX  4.052401    3.553234     5.717543
  </code></pre>