On Thu, 18 Mar 2010, Ben Bimber wrote:

I have a data frame containing the Id, Mother, Father and Sex from about
10,000 animals in our colony.  I am interested in graphing simple family
trees for a given subject or small number of subjects.  The basic idea is:
start with data frame from entire colony and list of index animals.  I need
to identify all immediate relatives of these index animals and plot the
pedigree for them.  We're not trying to do any sort of real analysis, just
present a visualization of the family structure.  I have used the kinship
and pedigree packages to plot the pedigree.  My question relates to
efficiently identifying the animals to include in the pedigree:

Starting with the data frame of ~10,000 records, I want to use a set of
index animals to extract the immediate relatives and plot only a small
number in the pedigree.  'Immediate relatives' is somewhat of an ambiguous
term - I am currently defining it as 3 generations forward and 3 backward.
Currently, I have a somewhat ugly approach where I recursively calculate
each generation forward or backward and build a new dataframe.  Is there a
better approach or package that does this?  I realize my code should be
written better to get rid of the loops, so if anyone has suggestions there I
would appreciate this as well.  Thanks in advance.


Using an indicator matrix for parent/child relations, you can identify future/past generations using matrix multiplication(s).

Since you have 10000 animals, the matrix indicating parents/children will be 10000 x 10000, but will have <20000 non-zero elements.

To me, this sounds like a good candidate for a sparse matrix representation. Packages 'Matrix' and 'SparseM' provide these.

HTH,

Chuck



Code to calculate generations forward and backward:

#queryIds holds the unique Ids for parents of the index animals
queryIds = unique(c(ped$Sire, ped$Dam));
for(i in 1:gens){
   if (length(queryIds) == 0){break};

   #allPed is the dataframe with Id,Dam,Sire and Sex for animals in our
colony
   newRows <- subset(allPed, Id %in% queryIds);
   queryIds = c(newRows$Sire, newRows$Dam);
   ped <- unique(rbind(newRows,ped));
}


#build forwards
#when calculating children, queryIds holds the Ids of the previous
generation
queryIds = unique(ped$Id);
for(i in 1:gens){
   if (length(queryIds)==0){break};

   #allPed is the dataframe with Id,Dam,Sire and Sex for animals in our
colony
   newRows <- subset(allPed, Sire %in% queryIds | Dam %in% queryIds);
   queryIds = newRows$Id;
   ped <- unique(rbind(newRows,ped));
}

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Charles C. Berry                            (858) 534-2098
                                            Dept of Family/Preventive Medicine
E mailto:cbe...@tajo.ucsd.edu               UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901

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