title: R ddply row summary statistics
body: <p>For each row in my data frame below (defined by <code>FID_Bounda</code>, <code>NAME</code>, <code>DESCRIPTIO</code> &amp; <code>SOVEREIGNT</code>) I'm trying to calculate the mean, standard deviation and the co-efficient of variation across all the values in each column starting with <code>crN</code>. </p>
  
  <pre><code>structure(list(FID_Bounda = 0:7, NAME = c("Bedfordshire", "Berkshire", 
  "Bristol", "Buckinghamshire", "Cambridgeshire", "Cheshire", "Derbyshire", 
  "Devon"), DESCRIPTIO = c("Ceremonial County", "Ceremonial County", 
  "Ceremonial County", "Ceremonial County", "Ceremonial County", 
  "Ceremonial County", "Ceremonial County", "Ceremonial County"
  ), SOVEREIGNT = c("England", "England", "England", "England", 
  "England", "England", "England", "England"), crN1 = c(61.944107636, 
  38.769347117, 0.810167027, 63.721241962, 191.046323469, 81.467146994, 
  61.65529268, 288.751788714), crN10 = c(60.33595964, 38.326639788, 
  0.834289164, 63.009539538, 185.25772542, 82.936101454, 61.985178493, 
  304.951827268), crN100 = c(53.385110882, 33.530058107, 0.739041324, 
  55.601839364, 165.604271128, 76.386014559, 55.591194915, 284.739586188
  ), crN1000 = c(58.397452282, 37.277298648, 0.820739862, 61.716749153, 
  175.436497697, 82.461823706, 61.762203751, 321.414544333)), .Names = c("FID_Bounda", 
  "NAME", "DESCRIPTIO", "SOVEREIGNT", "crN1", "crN10", "crN100", 
  "crN1000"), row.names = c(NA, 8L), class = "data.frame")
  </code></pre>
  
  <p>I tried to use the code outlined on <a href="http://www.cookbook-r.com/Manipulating_data/Summarizing_data/" rel="nofollow">cookbook-r</a> to derive these values:</p>
  
  <pre><code>cdata &lt;- ddply(uadt, c("FID_Bounda","NAME","DESCRIPTIO","SOVEREIGNT"), summarise,
                 N    = length(grep("crN", names(uadt), value = T)),
                 mean = mean(grep("crN", names(uadt), value = F)),
                 sd   = sd(grep("crN", names(uadt), value = F)),
                 se   = sd / sqrt(N)
  )
  cdata
  </code></pre>
  
  <p>Which correctly counts the total N of <code>crN</code> columns but it gives the same mean, sd and se for every row. Any help as to where the issue lies would be much appreciated as the real data set has 1000 columns all with the same naming pattern of <code>crNnumber</code>.</p>