PROC CLUSTER: How to get the hierarchy of nodes for each observation?

onechrister — Thu, 29 Aug 2019 20:44:03 GMT

Hi,

I use PROC CLUSTER and PROC TREE to do hierarchical clustering and draw dendrograms. My input data typically features around thousand observations. As part of the analysis I output (using the outtree= option) the hierarchy of linkages (denoted as CL1, CL2, CL3,…) between the observations (e.g., Obs1, Obs2, Obs3,…). This information is provided in the output variables _NAME_ and _PARENT_ .

My question is: how can I get the hierarchy of linkages (i.e., notes) listed for each observation, as a string? And can this be done in a generic manner such that it is applicable to data sets with thousands of observations?

Simple example: one has a data set with ten observations. Using PROC CLUSTER one gets an output specifying the following linkages between nodes and observations:

_NAME_ _PARENT_

CL1

CL2 CL1

CL3 CL1

CL4 CL2

CL5 CL3

CL6 CL4

CL7 CL5

CL8 CL4

CL9 CL2

Obs1 CL9

Obs10 CL7

Obs2 CL9

Obs3 CL3

Obs4 CL6

Obs5 CL6

Obs6 CL7

Obs7 CL5

Obs8 CL8

Obs9 CL8

I would like to generate (in a generic manner) an additional output specifying the hierarchy (sequence) of nodes for all the observations. Like this:

Observation Hierarchy

Obs1 CL1_CL2_CL9

Obs2 CL1_CL2_CL9

Obs4 CL1_CL2_CL4_CL6

Obs5 CL1_CL2_CL4_CL6

Obs8 CL1_CL2_CL4_CL8

Obs9 CL1_CL2_CL4_CL8

Obs10 CL1_CL3_CL5_CL7

Obs6 CL1_CL3_CL5_CL7

Obs7 CL1_CL3_CL5

Obs3 CL1_CL3

I would greatly appreciate if someone could point me towards a solution?

Thanks a lot in advance!

Re: PROC CLUSTER: How to get the hierarchy of nodes for each observation?

PGStats — Fri, 30 Aug 2019 03:59:11 GMT

Hash objects are efficient for this kind of processing. Try :

data want;
if 0 then set have;
length hier $100;
if _N_ = 1 then do;  
    declare hash h(dataset: "have");
    h.definekey("_NAME_");
    h.definedata("_NAME_", "_PARENT_");
    h.definedone();
end;
declare hiter hList('h');
_rc = hList.first();
do until(hList.next() ne 0);
    if substr(_name_,1,2) ne "CL" then do;
        n = _name_; hier = _parent_;
        do while(h.find(key:_PARENT_) = 0);
            hier = catx("_", _parent_, hier);
            end;
        output;
        end;
    end;
stop;
drop _name_ _parent_ _rc;
rename n=_name_;
run;

Re: PROC CLUSTER: How to get the hierarchy of nodes for each observation?

onechrister — Fri, 30 Aug 2019 08:54:39 GMT

Thank you very much!

It works like a charm!

topic Re: PROC CLUSTER: How to get the hierarchy of nodes for each observation? in New SAS User

PROC CLUSTER: How to get the hierarchy of nodes for each observation?

Re: PROC CLUSTER: How to get the hierarchy of nodes for each observation?

Re: PROC CLUSTER: How to get the hierarchy of nodes for each observation?