# [R] Convert back to lower triangular matrix

Jeff Newmiller jdnewmil at dcn.davis.ca.us
Tue Nov 15 23:50:24 CET 2011

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Juliet Ndukum <jpntsang at yahoo.com> wrote:

>Given a vector;> ab = seq(0.5,1, by=0.1)> ab[1] 0.5 0.6 0.7 0.8 0.9 1.0
>The euclidean distance between the vector elements is given by the
>lower triangular matrix�> dd1 = dist(ab,"euclidean")> dd1� � 1 � 2 � 3
>� 4 � 52 0.1 � � � � � � � �3 0.2 0.1 � � � � � �4 0.3 0.2 0.1 � � � �5
>0.4 0.3 0.2 0.1 � �6 0.5 0.4 0.3 0.2 0.1
>Convert the lower triangular matrix to a full matrix> ddm =
>as.matrix(dd1)> ddm� � 1 � 2 � 3 � 4 � 5 � 61 0.0 0.1 0.2 0.3 0.4 0.52
>0.1 0.0 0.1 0.2 0.3 0.43 0.2 0.1 0.0 0.1 0.2 0.34 0.3 0.2 0.1 0.0 0.1
>0.25 0.4 0.3 0.2 0.1 0.0 0.16 0.5 0.4 0.3 0.2 0.1 0.0
>I would be grateful if someone could provide me with a code to convert
>ddm to the lower triangular matrix as before i.e. dd1
> above.
>Your help will be greatly appreciated.JN
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