Check for MACS2 before splitting file

[AmelZulji]

When calling peaks using:

peaks <- CallPeaks(
  object = seu,
  group.by = "cell_type",
  macs2.path = "wrong_path"
)

splitting fragments will start before checking whether specified macs2.path points to existing instance of MACS2. It would be nice to first check for MACS2.

[timoast]

What version are you using? This should indeed be happening before splitting files:

signac/R/peaks.R

Lines 80 to 89 in 8b98f63

	if (!is.null(x = group.by)) {
	# first check macs2 path before we spend time splitting the files
	macs2.path <- SetIfNull(
	x = macs2.path,
	y = unname(obj = Sys.which(names = "macs2"))
	)
	if (nchar(x = macs2.path) == 0) {
	stop("MACS2 not found. Please install MACS:",
	"https://macs3-project.github.io/MACS/")
	}

[timoast]

Ah, nevermind, I see what you're saying. We only check if there is a path, not that there's a functional MACS at that path. Ok, we can try to add that check.

[AmelZulji]

Thank you!