8. [ThinkPython: Lists](lists.md)

Now we have learned to save values to variables.

thing = 'Hello World!'

Then we can do whatever we want with the variable.

print(thing)

But what if you have a lot of values? You can just make a lot of

variables...

thing1 = 'Hello World!'

thing2 = 'hi'

thing3 = 123

thing4 = 3.14

thing5 = 42

thing6 = 'This is yet another thing.'

thing7 = 'Python is fun!'

print(thing1)

print(thing2)

print(thing3)

print(thing4)

print(thing5)

print(thing6)

print(thing7)

...or you can use a list and keep everything in one variable.

things = ['Hello World!', 'hi', 123, 3.14, 42,

'This is yet another thing.', 'Python is fun!']

for thing in things:

print(thing)

[Read more about lists in ThinkPython

here.](http://greenteapress.com/thinkpython2/html/thinkpython2011.html)

Skip the chapter "10.7 Map, filter and reduce" and the excercises. You

would need to know how to define functions using the `def` keyword, but

we haven't talked about that yet.

- Lists are a way to store multiple values in one variable. We can

create lists by putting whatever we want inside [square brackets],

for example, `our_list = []` creates an empty list.

- Never do `list = ...`. `list` is a built-in class, and it's used for

converting other values to lists, like `list_of_thingy = list(thingy)`.

If we do `list = something`, then `list(thingy)` will probably do

something else than we want it to do.

- When we have created a list, we can slice it. For example,

`our_list[2:]` results in a new list with everything in the

original list except the first two elements. Negative indexes start

from the end of the list, for example, `our_list[-2:]` is a list of

the last two elements.

- We can also index lists, `our_list[0]` is the first element in the

list. Non-negative indexes start at zero, and negative indexes

start at -1.

- You can assign to indexes and slices like `some_list[0] = 'hi'`, or

delete them like `del some_list[:2]`.

- `a = b` does not create a copy of b.

```py

>>> a = []

>>> b = a # this does not copy anything

>>> b += [1, 2, 3]

>>> a

[1, 2, 3]

>>>

```

If you want a copy, use the `.copy()` list method:

```py

>>> a = []

>>> b = a.copy()

>>> b += [1, 2, 3]

>>> a

[]

>>>

```

You may use this tutorial freely at your own risk. See [LICENSE](LICENSE).

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