OneHot

features x depth if axis == -1
   depth x features if axis == 0
 

batch x features x depth if axis == -1
   batch x depth x features if axis == 1
   depth x batch x features if axis == 0
 

indices = [0, 2, -1, 1]
   depth = 3
   on_value = 5.0
   off_value = 0.0
   axis = -1
 

output =
   [5.0 0.0 0.0]  // one_hot(0)
   [0.0 0.0 5.0]  // one_hot(2)
   [0.0 0.0 0.0]  // one_hot(-1)
   [0.0 5.0 0.0]  // one_hot(1)
 

indices = [0, 2, -1, 1]
   depth = 3
   on_value = 0.0
   off_value = 3.0
   axis = 0
 

output =
   [0.0 3.0 3.0 3.0]
   [3.0 3.0 3.0 0.0]
   [3.0 3.0 3.0 3.0]
   [3.0 0.0 3.0 3.0]
 //  ^                one_hot(0)
 //      ^            one_hot(2)
 //          ^        one_hot(-1)
 //              ^    one_hot(1)
 

indices = [[0, 2], [1, -1]]
   depth = 3
   on_value = 1.0
   off_value = 0.0
   axis = -1
 

output =
   [
     [1.0, 0.0, 0.0]  // one_hot(0)
     [0.0, 0.0, 1.0]  // one_hot(2)
   ][
     [0.0, 1.0, 0.0]  // one_hot(1)
     [0.0, 0.0, 0.0]  // one_hot(-1)
   ]