title: Looping with Multiple Parameters without the for loop
body: <p>Below is a micro-version of my data set. I would like to loop through the three variables without using the 'for' function.</p>
  
  <p>Reproducible Version of the Subject Data Set</p>
  
  <pre><code>cat1 &lt;- rep(c("A","S"),each=40)# First variable
  cat2 &lt;- rep(c("C","M","Y","K"), each=10, times=2) # Second variable
  num1 &lt;- rep(c(0,10,20,30,40,45,65,80,90,100),8) # Third variable
  rspns &lt;-structure(list(dataSet = c(0.2484375, 0.3959375, 0.4875, 0.57875, 0.6696875, 0.694375,
      0.816875, 0.879375, 0.9121875, 0.93125, 0.25125, 0.3796875, 0.4609375, 0.5396875, 0.6159375,
      0.6515625, 0.7696875, 0.8384375, 0.864375, 0.8865625, 0.271875, 0.39875, 0.4821875,
      0.5628125, 0.6284375, 0.650625, 0.7553125, 0.8003125, 0.8103125, 0.8125, 0.251875, 0.3775,
      0.4703125, 0.5725, 0.6996875, 0.7378125, 0.945, 1.055625, 1.1021875, 1.1140625, 0.25125,
      0.4203125, 0.5215625, 0.615625, 0.71, 0.74, 0.865625, 0.9246875, 0.9603125, 0.9734375,
      0.256875, 0.3953125, 0.4775, 0.5528125, 0.62875, 0.65875, 0.78375, 0.8384375, 0.8653125,
      0.8740625, 0.2790625, 0.4215625, 0.515, 0.6009375, 0.6665625, 0.693125, 0.7959375, 0.83875,
      0.8490625, 0.8575, 0.2571875, 0.3759375, 0.4665625, 0.56375, 0.68875, 0.725, 0.9259375,
      1.0328125, 1.085625, 1.1096875)), .Names = "rspns",
    class = "data.frame", row.names = c(NA, -80L))
  gain &lt;- data.frame(cat1,cat2,num1, rspns=rspns)
  
  tint &lt;-  function(x,y,z) gain[cat1 == x &amp; cat2 == y &amp; num1 == z, 4]
  dgain &lt;- function(x,y,z){(100* (1-10^-(tint(x,y,z) - tint(x,y,0))) / (1-10^-(tint(x,y,100)- tint(x,y,0)))) - z}
  </code></pre>
  
  <p>How can I get the <code>dgain</code> function, which takes three parameters, to loop through <code>cat1</code>, <code>cat2</code> and <code>num1</code> variables without using <code>for</code> loops?</p>
  
  <p>Your help and technical expertise is greatly appreciated.</p>