Half size of edge number

[LouiValley]

Excuse me. I tried the dataset, e.g., PubMed. from data

| # of nodes : 19717
| # of edges : 44325.5
| # of features : 500
| # of clases   : 3
| # of train set : 60
| # of val set   : 500
| # of test set  : 1000

It reports the edge number is 44,325.5. However, many papers point out that the edge number of PubMed is 88,648. Why does it only have half size?