In place operations

It is important to understand the difference between in place and assignment operations. When, for example, we use transpose(x), a value is returned but the value of x does not change. In all the examples up until now, we have been performing operations by assignment. That is, we have been assigning a variable to the result of an operation, or simply printing it to the output, as in the preceding example. In either case, the original variable remains untouched. Alternatively, we may need to apply an operation in place. We can, of course, assign a variable to itself, such as in x = x.transpose(0,1); however, a more convenient way to do this is with in place operations. In general, in place operations in PyTorch have a trailing underscore. For an example, see the following code:

As another example, here is the linear function we started this chapter with using in place operations on y: