it should be noted that when performing operations on arrays that create listssuch as list comprehensionsthe memory efficiency gains of using an array in the first place will be negated when we need to create new data objecta solution is to use generator expression to perform the operationfor examplearrays created with this module are unsuitable for work that requires matrix of vector operations in the next we will build our own abstract data type to deal with these operations also important for numerical work is the numpy extensionavailable at www numpy org summary in the last two we have examined the language features and data types of python we have looked at the built-in data types and some internal python modulesmost notably the collections module there are also several other python modules that are relevant to the topic of this bookbut rather than examining them separatelytheir use and functionality should become self-evident as we begin using them there are also number of external libraries such as the scipy stackandlikewisei will attempt to explain their basic functionality as we begin to apply them in the next we will introduce the basic theory and techniques of algorithm design