title: R Error : some group is too small for 'qda'
body: <p>I used the qda{MASS} to find the classfier for my data and it always reported "<code>some group is too small for 'qda'</code>". Is it due to the size of test data I used for model ? I increased the test sample size from 30 to 100, it reported the same error. Helpppppppp.....</p>
  
  <pre><code>set.seed(1345)
  AllMono &lt;- AllData[AllData$type == "monocot",]
  MonoSample &lt;- sample (1:nrow(AllMono), size = 100, replace = F)
  set.seed(1355)
  AllEudi &lt;- AllData[AllData$type == "eudicot",]
  EudiSample &lt;- sample (1:nrow(AllEudi), size = 100, replace = F)
  testData &lt;- rbind (AllMono[MonoSample,],AllEudi[EudiSample,])
  plot (testData$mono_score, testData$eudi_score, col = as.numeric(testData$type), xlab = "mono_score", ylab = "eudi_score", pch = 19)
  qda (type~mono_score+eudi_score, data = testData)
  </code></pre>
  
  <p>Here is my data example</p>
  
  <pre><code>&gt;head (testData)
                                sequence mono_score eudi_score    type
  PhHe_4822_404_76       DTRPTAPGHSPGAGH    51.4930   39.55000 monocot
  SoBi_10_265860_58      QTESTTPGHSPSIGH    33.1408    2.23333 monocot
  EuGr_5_187924_158        AFRPTSPGHSPGAGH    27.0000   54.55000 eudicot
  LuAn_AOCW01152859.1_2_79 NFRPTEPGHSPGVGH    20.6901   50.21670 eudicot
  PoTr_Chr07_112594_90     DFRPTAPGHSPGVGH    43.8732   56.66670 eudicot
  OrSa.JA_3_261556_75    GVRPTNPGHSPGIGH    55.0986   45.08330 monocot
  PaVi_contig16368_21_57 QTDSTTPGHSPSIGH    25.8169    2.50000 monocot
  
  &gt;testData$type &lt;- as.factor (testData$type)
  
  &gt; dim (testData)
  [1] 200   4
  
  &gt; levels (testData$type)
  [1] "eudicot" "monocot" "other" 
  
  &gt; table (testData$type)
  eudicot monocot   other 
      100     100       0
  
  &gt; packageDescription("MASS")
  Package: MASS
  Priority: recommended
  Version: 7.3-29
  Date: 2013-08-17
  Revision: $Rev: 3344 $
  Depends: R (&gt;= 3.0.0), grDevices, graphics, stats, utils
  </code></pre>
  
  <p>My R version is R 3.0.2. </p>