Fill Missing Cells
GGEbiplot provides 4 options to fill missing cells:
1) For each variable (column), fill the missing cell of an observation (row) using the weighted average of 5 observations (rows) that are most similar to the observation.
2) For each column, fill the missing cells using the mean across all other rows.
3) For each row, fill the missing cells using the mean across all other columns.
4) Fill the missing cells using the average of the respective row mean and of the respective column mean.
Number #2 is the default method of filling missing cells in GGEbiplot, but #1 might be more rational.