Why the results shows the same count from "source to target" and "target to source" ?

[siya-kk]

Hello,

Thank you for the wonderful software which help the investigation of cellular interaction. I have some small questions about the result.

1. For the "count_network.txt" file, it contain the count of interactions but why two groups always get same count, for example (below), to my understanding, the ligand or receptor expression from different cell should be different.

SOURCE TARGET count CD8 NK 42 NK CD8 42 CD4 BC 35 BC CD4 35

2. how can i know the exact count of ligand or receptor from each cell type ?

[danshu]

I have the sample question. After checking the script (https://github.com/Teichlab/cellphonedb/blob/master/cellphonedb/src/plotters/R/plot_heatmaps.R), this count is actualy the sum of all interactions between two cell types (e.g. CD8|NK + NK|CD8).