Collection of values appear everywhere in programs, and Julia has the most important built-in collection types. In Chapter 2, Variables, Types, and Operations, we introduced two important types of collections: arrays and tuples. In this chapter, we will look more deeply at multidimensional arrays (or matrices) and in the tuple type as well. A dictionary type, where you can look up a value through a key, is indispensable in a modern language, and Julia has this too. Finally, we will explore the set type. Like arrays, all these types are parameterized; the type of their elements can be specified at object construction time.
Collections are also iterable types, the types over which we can loop with for
or an iterator producing each element of the collection successively. The iterable types include string, range, array, tuple, dict, and set.
So, the following are the topics for this chapter:
Matrices
Tuples
Dictionaries
Sets
An example project: word frequency