官方文档解释：
To create a tensor with pre-existing data, use torch.tensor().
To create a tensor with specific size, use torch.* tensor creation ops (see Creation Ops).
To create a tensor with the same size (and similar types) as another tensor, use torch.*_like tensor creation ops (see Creation Ops).
To create a tensor with similar type but different size as another tensor, use tensor.new_* creation ops.
简单来说，
torch.tensor() 用的最多，一般都用它；
torch.* 用于创建特殊形式的 tensor，包括 torch.ones()、torch.zeros()等；
torch.*_like() 用于创建一个与已知 tensor 形状相同的 tensor；
torch.new_* 用于创建一个与已知 tensor 类型相同的 tensor
最后放一下参数表
torch.tensor(data, dtype=None, device=None, requires_grad=False, pin_memory=False) → Tensor
torch.ones(*size, out=None, dtype=None, layout=torch.strided, device=None, requires_grad=False) → Tensor
torch.ones_like(input, dtype=None, layout=None, device=None, requires_grad=False) → Tensor
torch.new_ones(size, dtype=None, device=None, requires_grad=False) → Tensor