title: subsetting a vector with column having value equal to zero
body: <p>I am trying to find out the best model for my data. But, i am getting following error while doing so. </p>
  
  <pre><code>list(
    lm(V7 ~ log(V3), hm, subset=(V3&gt;0)), 
    lm(V7~I(1/V3), hm, subset = (V3 &gt;0)),
    lm(V7 ~ log(V3), hm, subset(V3 &gt; 0)),
    nls(V7 ~ I(1/V3*a) + b*V3, hm, subset(V3 &gt; 0), start = list(a = 1, b = 1)), 
    nls(V7 ~ (a + b*log(V3)), hm, subset(V3 &gt; 0), 
      start = setNames(coef(lm(V7 ~ log(V3), hm, subset(V3 &gt; 0))), c("a", "b"))),
    nls(V7 ~ I(exp(1)^(a + b * V3)), hm, subset(V3 &gt; 0), 
      start = list(a=0,b=0)),
    nls(V7 ~ I(1/V3*a)+b, hm, subset(V3 &gt; 0), 
      start = list(a=1,b=1))
  )
  
   Error in subset.default(V3 &gt; 0) : 
   argument "subset" is missing, with no default
  </code></pre>