# 5.10 Other List Methods¶

In [1]:

    color_names = ['orange', 'yellow', 'green']

### Inserting an Element at a Specific List Index¶

In [2]:

    color_names
    .insert(0, 'red')

In [3]:

    color_names

Out[3]:

    ['red', 'orange', 'yellow', 'green']

### Adding an Element to the End of a List¶

In [4]:

    color_names
    .append('blue')

In [5]:

    color_names

Out[5]:

    ['red', 'orange', 'yellow', 'green', 'blue']

### Adding All the Elements of a Sequence to the End of a List¶

- Equivalent to `+=`.

In [6]:

    color_names
    .extend(['indigo', 'violet'])

In [7]:

    color_names

Out[7]:

    ['red', 'orange', 'yellow', 'green', 'blue', 'indigo', 'violet']

In [8]:

    sample_list = []

In [9]:

    s = 'abc'

In [10]:

    sample_list.extend(s)

In [11]:

    sample_list

Out[11]:

    ['a', 'b', 'c']

In [12]:

    t = (1, 2, 3)

In [13]:

    sample_list.extend(t)

In [14]:

    sample_list

Out[14]:

    ['a', 'b', 'c', 1, 2, 3]

- Parentheses are required for the tuple argument below, because `extend` expects one iterable argument.

In [15]:

    sample_list.extend((4, 5, 6))  # note the extra parentheses

In [16]:

    sample_list

Out[16]:

    ['a', 'b', 'c', 1, 2, 3, 4, 5, 6]

### Removing the First Occurrence of an Element in a List¶

- `ValueError` occurs if `remove`’s argument is not in the list.

In [17]:

    color_names
    .remove('green')

In [18]:

    color_names

Out[18]:

    ['red', 'orange', 'yellow', 'blue', 'indigo', 'violet']

### Emptying a List¶

In [19]:

    color_names
    .clear()

In [20]:

    color_names

Out[20]:

    []

### Counting the Number of Occurrences of an Item¶

In [21]:

    responses = [1, 2, 5, 4, 3, 5, 2, 1, 3, 3,
                 1, 4, 3, 3, 3, 2, 3, 3, 2, 2]

In [22]:

    for i in range(1, 6):
        print(f'{i} appears {responses.count(i)} times in responses')

    1 appears 3 times in responses
    2 appears 5 times in responses
    3 appears 8 times in responses
    4 appears 2 times in responses
    5 appears 2 times in responses

### Reversing a List’s Elements¶

- Method `reverse` reverses the contents of a list in place.

In [23]:

    color_names
     = ['red', 'orange', 'yellow', 'green', 'blue']

In [24]:

    color_names
    .reverse()

In [25]:

    color_names

Out[25]:

    ['blue', 'green', 'yellow', 'orange', 'red']

### Copying a List¶

- Method `copy` returns a new list containing a shallow copy.

In [26]:

    copied_list = color_names.copy()

In [27]:

    copied_list

Out[27]:

    ['blue', 'green', 'yellow', 'orange', 'red']

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