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Matrice elements extraction

Posted 10 years ago

Hi. I need a help

    I have defined the matrix "m" and the position ( variable index1) of the line in the first column.

    How do I extract the element defined by the position calculated and column 2. I want the element  m [3,2]. If a use
     m[[index1,2]] doesn't work.

    Thanks


        m = {{20, 0.004, na, na}, {18, 0.05, na, na}, {16, 0.06, na, na}, {14,
            0.074, 1.05, 0.5}, {12, 0.0104, 0.92, 0.5}, {10, 0.134, 0.82, na}}

        In[318]:= index1 = Position[{20, 18, 16, 14, 12, 10}, gagev]

        Out[318]= {{3}}

In[373]:= m[[index1, 2]]

During evaluation of In[373]:= Part::pkspec1: The expression {{3}} cannot be used as a part specification. >>

Out[373]= {{20, 0.004, na, na}, {18, 0.05, na, na}, {16, 0.06, na, 
   na}, {14, 0.074, 1.05, 0.5}, {12, 0.0104, 0.92, 0.5}, {10, 0.134, 
   0.82, na}}[[{{3}}, 2]]
2 Replies
Priyan.
 Thank you very much. 
Posted 10 years ago

This happens cause index1 equals {{3}} not 3. Hence replace index1 with index1[[1]][[1]] in the m[[index1,2]] term.

POSTED BY: Priyan Fernando
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