Finds connected data sets, i.e. connected rows and columns
of a numeric matrix M.
Usage
connectedSets(M)
Arguments
M
Numeric matrix with 0-entries considered as missing values.
Value
rowclassesVector of set numbers of rows of M.
colclassesVector of set numbers of columns of M.
Details
In a two-way classification of linear models sometimes independent
sets of normal equations are obtained due to missing data in the
experiments design, i.e. the complete design matrix is not of full rank
and thus no solution can be found. However, solutions of the independent
sets of normal equations can still exist.
This phenomenon is called 'connectedness' of the data.
Especially in phenological analysis experimental designs are almost
always unbalanced because of missing data. Thus, when combined time
series are to be estimated, it is worth checking for and finding
connected data sets for which combined time series can then be estimated.
Example (also see example data(Simple) and example in 'maxConnectedSets'):
In the following matrix dots represent missing values, X represent observations
and the lines join the connected sets:
: X___X . .
: $\mid$
: X___X . .
:
: . . X___X
Thus, in this matrix observations in rows 1 and 2 or colums 1 and 2 form one connected
set. Likewise row 3 (or columns 3 and 4) form also one connected set.