🔨 The dim Collapse Visualizer
A hydraulic press squishes exactly the axis you select — watch which one actually disappears.
📋 How To Use This Lab
Pick
dim=0
or
dim=1
→
the press repositions to show which axis it's about to squish.
Press
🔨 Collapse!
→
watch it physically flatten that axis, real sums appearing live.
dim=0
presses
top-to-bottom
(vertical) — the 3 floors squish into 1.
dim=1
presses
side-to-side
(horizontal) — the 4 columns squish into 1.
Flip
keepdim
→
see whether the squished axis survives as size-1 or vanishes completely.
(3, 4, 2)
➜
sum(dim=0) → (4, 2)
torch.sum(x, dim=0) — press comes from the TOP
dim = 0
dim = 1
keepdim=False
keepdim=True
🔨 Collapse!
↺ Reset
🔨 SQUISH
Pick a dim and press Collapse — I'll show you exactly which axis gets flattened.
🧑🏫 PROF. TORCH
dim=N means "sum ALONG this axis" — that axis is what disappears, not what survives.