Lining dictionaries up in a list

The answer is to line the dictionaries up inside a list. Between [ and ] you write dictionaries separated by commas.

Read it like this: the list is the whole register, each dictionary is one person. Hold on to that sentence and the rest is only tools you already have.

people[0] was a dictionary. A dictionary can be looked up by key, so you can carry straight on with ["name"].

Read people[0]["name"] from the left.

• people[0] … the first record in the register (a dictionary)
• ["name"] … the name in that dictionary

Trying to take it in at once is confusing, so the knack is to read one set of brackets at a time.

Here is the main event. Write for person in people: and each time round, one dictionary arrives in person.

What you get is a dictionary, so inside you write person["name"]. However many people there are, the code is the same. Two or a thousand, it is these three lines.

You can use if inside the loop too. Look at one record, decide, produce a result — what you did in chapter 1 now applies to everybody.

This is what it means for a program to become useful. Instead of a person going through a hundred records by eye, the same decision is handed to the machine.

A total or an average comes out the same way. Set up the container first and add as you go round, and that is it.

Do not forget to put the print outside the loop. Inside, and every running figure comes out as well.

A register is a list, so the list tools work as they always did. append adds one record. What you hand it is a dictionary.

In other words this shape is what you know about lists laid straight over what you know about dictionaries. There is almost nothing new to learn.

Next comes the last of this group: the tuple, a group you cannot change afterwards.