# C3-4: Pandas

August 29, 2019•1,003 words

# C3-4: Pandas

## L1: Anaconda

## L2: Jupyter Notebooks

## L3: NumPy

## L4: Pandas

### Creating Pandas Series

**import pandas as pd** | Import Pandas

my_series = **pd.Series**(**data =** ['data1', 'data2', data3', 'data4'], **index =** ['row1', 'row2', 'row3', 'row4']) | Creates Series

**my_series** # Display Series

**my_series.shape** # Show shape as tuple

**my_series.ndim** # Dimensions as int

**my_series.size** # Number of elements

**my_series.index** # Show index

**my_seriex.values** # Show values

**x = bananas in my_series** # Check if 'bananas' is an index label, returns True or False

```
# We import Pandas as pd into Python
import pandas as pd
# We create a Pandas Series that stores a grocery list
groceries = pd.Series(data = [30, 6, 'Yes', 'No'], index = ['eggs', 'apples', 'milk', 'bread'])
# We display the Groceries Pandas Series
groceries
```

eggs 30

apples 6

milk Yes

bread No

dtype: object

```
# We print some information about Groceries
print('Groceries has shape:', groceries.shape)
print('Groceries has dimension:', groceries.ndim)
print('Groceries has a total of', groceries.size, 'elements')
```

Groceries has shape: (4,)

Groceries has dimension: 1

Groceries has a total of 4 elements

```
# We print the index and data of Groceries
print('The data in Groceries is:', groceries.values)
print('The index of Groceries is:', groceries.index)
```

The data in Groceries is: [30 6 'Yes' 'No']

The index of Groceries is: Index(['eggs', 'apples', 'milk', 'bread'], dtype='object')

```
# We check whether bananas is a food item (an index) in Groceries
x = 'bananas' in groceries
# We check whether bread is a food item (an index) in Groceries
y = 'bread' in groceries
# We print the results
print('Is bananas an index label in Groceries:', x)
print('Is bread an index label in Groceries:', y)
```

Is bananas an index label in Groceries: False

Is bread an index label in Groceries: True

### Accessing and Deleting Elements in Pandas

**my_series['apples']** # Access element using a single label

**my_series[['apples', 'pears']]** # Access element using two or more labels

**.loc | .iloc** # The attribute .loc stands for location and it is used to explicitly state that we are using a labeled index. Similarly, the attribute .iloc stands for integer location and it is used to explicitly state that we are using a numerical index. Let's see some examples:

```
# We access elements in Groceries using index labels:
# We use a single index label
print('How many eggs do we need to buy:', groceries['eggs'])
print()
# we can access multiple index labels
print('Do we need milk and bread:\n', groceries[['milk', 'bread']])
print()
# we use loc to access multiple index labels
print('How many eggs and apples do we need to buy:\n', groceries.loc[['eggs', 'apples']])
print()
# We access elements in Groceries using numerical indices:
# we use multiple numerical indices
print('How many eggs and apples do we need to buy:\n', groceries[[0, 1]])
print()
# We use a negative numerical index
print('Do we need bread:\n', groceries[[-1]])
print()
# We use a single numerical index
print('How many eggs do we need to buy:', groceries[0])
print()
# we use iloc to access multiple numerical indices
print('Do we need milk and bread:\n', groceries.iloc[[2, 3]])
```

How many eggs do we need to buy: 30

Do we need milk and bread:

milk Yes

bread No

dtype: object

How many eggs and apples do we need to buy:

eggs 30

apples 6

dtype: object

How many eggs and apples do we need to buy:

eggs 30

apples 6

dtype: object

Do we need bread:

bread No

dtype: object

How many eggs do we need to buy: 30

Do we need milk and bread:

milk Yes

bread No

dtype: object

Pandas Series are also mutable like NumPy ndarrays, which means we can change the elements of a Pandas Series after it has been created. For example, let's change the number of eggs we need to buy from our grocery list.

```
# We display the original grocery list
print('Original Grocery List:\n', groceries)
# We change the number of eggs to 2
groceries['eggs'] = 2
# We display the changed grocery list
print()
print('Modified Grocery List:\n', groceries)
```

Original Grocery List:

eggs 30

apples 6

milk Yes

bread No

dtype: object

Modified Grocery List:

eggs 2

apples 6

milk Yes

bread No

dtype: object

We can also delete items from a Pandas Series by using the **.drop() method**. The Series.drop(label) method removes the given label from the given Series. We should note that the **Series.drop(label)** method **drops elements from the Series out of place**, meaning that it doesn't change the original Series being modified. Let's see how this works:

```
# We display the original grocery list
print('Original Grocery List:\n', groceries)
# We remove apples from our grocery list. The drop function removes elements out of place
print()
print('We remove apples (out of place):\n', groceries.drop('apples'))
# When we remove elements out of place the original Series remains intact. To see this
# we display our grocery list again
print()
print('Grocery List after removing apples out of place:\n', groceries)
```

Original Grocery List:

eggs 30

apples 6

milk Yes

bread No

dtype: object

We remove apples (out of place):

eggs 30

milk Yes

bread No

dtype: object

Grocery List after removing apples out of place:

eggs 30

apples 6

milk Yes

bread No

dtype: object

We can **delete items** from a Pandas Series in place by **setting the keyword inplace to True** in the .drop() method. Let's see an example:

```
# We display the original grocery list
print('Original Grocery List:\n', groceries)
# We remove apples from our grocery list in place by setting the inplace keyword to True
groceries.drop('apples', inplace = True)
# When we remove elements in place the original Series its modified. To see this
# we display our grocery list again
print()
print('Grocery List after removing apples in place:\n', groceries)
```

Original Grocery List:

eggs 30

apples 6

milk Yes

bread No

dtype: object

Grocery List after removing apples in place:

eggs 30

milk Yes

bread No

dtype: object