Single cell- feature plots and dot plots

[isaiao01]

I am analyzing a pbmc/tumor experiment

In the general populations(looking at the oxygen groups) the CD14 dot is purple(high average expression) in normoxia, but specifically in macrophage population it is gray(low average expression).

So my question is why is this? Because when we look to the feature plot, it looks like CD14 is mostly expressed only in macrophages.

Just a note to give everyone background: Hypoxia cells are 754 in total and Normoxia are 6601. Specifically in macrophages, they are 109 hypoxic cells vs 1319 normoxic cells.

This is my code for the Oxygen population (so all celltypes):

Idents(OC) <- "Oxygen"

seurat_subset <- subset(x = OC, idents = c("Physoxia"), invert = TRUE)

DotPlot(seurat_subset, features = c("CD14"))

This is my code for the Macrophage Oxygen population:

subset_macrophage <- subset(OC, idents = "Macrophages") %>%

subset(Oxygen %in% c("Hypoxia", "Normoxia"))

DotPlot(subset_macrophage, features = c("CD14"), split.by = "Oxygen")

Am i making a mistake by saying split by oxygen here instead of group by?