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      lang="x-western">Hi rcpp-devel,

      <br>

      <br>

      How&nbsp;can&nbsp;I&nbsp;test&nbsp;if&nbsp;a&nbsp;member&nbsp;of&nbsp;a&nbsp;list&nbsp;is&nbsp;a&nbsp;NULL&nbsp;value&nbsp;?

      <br>

      <br>

      I&nbsp;have&nbsp;this&nbsp;kind&nbsp;of&nbsp;R&nbsp;code<br>

      <br>

      <address>#&nbsp;create&nbsp;a&nbsp;list&nbsp;with&nbsp;all&nbsp;the&nbsp;parameters&nbsp;for&nbsp;initializing&nbsp;the&nbsp;algorithms

      </address>

      <address>`initAlgo`&lt;-function(&nbsp;algo="EM"

      </address>

      <address>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;,&nbsp;init=&nbsp;NULL

      </address>

      <address>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;,&nbsp;nbTry=&nbsp;NULL

      </address>

      <address>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;)

      </address>

      <address>{

      </address>

      <address>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;listOptions&nbsp;&lt;-&nbsp;list(&nbsp;algo=&nbsp;algo,&nbsp;init=&nbsp;init,&nbsp;nbTry=&nbsp;nbTry&nbsp;)

      </address>

      <address>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;listOptions

      </address>

      <address>}

      </address>

      <br>

      <address># call c/C++</address>

      <address>&nbsp;res_cluster&nbsp;&lt;-&nbsp;.Call("MyFunction",&nbsp;data,&nbsp;options&nbsp;=&nbsp;initAlgo())

      </address>

      <address><br>

      </address>

      <br>

      and&nbsp;this&nbsp;kind&nbsp;of&nbsp;C/C++&nbsp;code

      <br>

      <br>

      <address>cppExport&nbsp;SEXP&nbsp;MyFunction(&nbsp;SEXP&nbsp;data,&nbsp;SEXP&nbsp;algoOptions)

      </address>

      <address>{

      </address>

      <address>BEGIN_RCPP

      </address>

      <address><br>

        &nbsp;&nbsp;&nbsp;//&nbsp;wrap&nbsp;data&nbsp;in&nbsp;Rcpp&nbsp;matrix

      </address>

      <address>&nbsp;&nbsp;&nbsp;Rcpp::NumericMatrix&nbsp;RData(data);&nbsp;//&nbsp;creates&nbsp;Rcpp&nbsp;matrix&nbsp;from&nbsp;SEXP

      </address>

      <address>&nbsp;&nbsp;&nbsp;//&nbsp;wrap&nbsp;list&nbsp;algoOptions

      </address>

      <address>&nbsp;&nbsp;&nbsp;Rcpp::List&nbsp;RalgoOptions(algoOptions);

      </address>

      <address><br>

        ..........

      </address>

      <address>}

      </address>

      <address><br>

      </address>

      <br>

I&nbsp;would&nbsp;like&nbsp;to&nbsp;test&nbsp;if&nbsp;the&nbsp;init&nbsp;and&nbsp;nbTry&nbsp;parameter&nbsp;in&nbsp;the&nbsp;RalgoOptions&nbsp;are&nbsp;NULL&nbsp;and&nbsp;I&nbsp;don't&nbsp;find

      <br>

      any&nbsp;documentation&nbsp;about&nbsp;the&nbsp;way&nbsp;to&nbsp;do&nbsp;it.

      <br>

      <br>

      Thanks

      <br>

      Serge&nbsp;Iovleff

      <span class="moz-txt-tag"></span><br>

      <div class="moz-txt-sig">

        <br>

      </div>

    </div>

    <pre class="moz-signature" cols="100">-- 

USTL - IUT "A" - 3A56    | Tel: (33) 3 59 63 22 20

D&eacute;partement Informatique | Fax: (33) 3 59 63 22 22

BP 90179                 | www.iut-info.univ-lille1.fr/~iovleff

59653 Villeneuve d'Ascq  | Serge.Iovleff@univ-lille1.fr

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