title: Count number of rows meeting multiple conditions in dataframe
body: <p>I have a question. I'm working on a database with patients and multiple conditions I scored as yes/no or numbers. I first counted the number of patients (rows) in which patients meet at least one criteria of 5, see this code (working):</p>
  
  <pre><code>nrow( df_1[df_1$tenderness_CS != 'no' | df_1$intoxication != 'no' |    
             df_1$focal_neuro_deficits != 'no' | df_1$EMV &lt;= 13 | df_1$distr_injury != 'no',] )
  </code></pre>
  
  <p>But now I want to count how many patients meet 2, 3 and 4 criteria of the above standing. Doesn't matter which of the 5 criteria are met, just if 2 or 3 are met. I really don't know how to do that. </p>
  
  <p>Any help? Thanks!</p>