Intro to Pandas Data structures series Dataframe ndarray

Python-Pandas-Intro

In this article, we are going to learn about the intro to Pandas Data structures series Dataframe ndarray with code examples, how to create and use them, and difference. Mainly array, ndarray, series, and Dataframes are used widely while working with Pandas. Today we will learn about one of these data structures on Pandas.

Types of Data Structures in Pandas

Types of data structures in Pandas that widely used working with Pandas

  • ndarray – N Dimensional Array
  • Pandas Data structure: Pandas Series
  • Dataframes

1. ndarray – N Dimensional Array

We will learn about ndarray which is part of the NumPy library. Pandas use the ndarray for a lot of functions. Let us briefly understand what is ndarray.

Program Example 1D ndarray

import numpy as np
np_array = np.random.rand(4)
print(type(np_array))
print(np_array[0])

Here we can see the output as np_array is of type ndarray. And also we can see the random value generated by np.random.rand at index 0. We are using a 1-D array, but this can be created as a 2-D or N-D array also.

Output:

<class 'numpy.ndarray'>
0.179953500159113

Program Example 2D ndarray

In the below example we can see how 2-D ndarray can be created in Numpy

import numpy as np
nd_array = np.random.rand(4,2)
print(type(nd_array))
print(nd_array[2,1])

Output:

<class 'numpy.ndarray'>
0.09759443425495462

2. Pandas Data structure: Pandas Series

The Pandas Series are used in manipulating data frames and other operations on data. Data can be read in the form of this data structure and then operated upon. Series is a one-column data structure. Let us understand with examples what is panda series.

Program Example

We passed the ndarray to the Series and got the series output. Here we can see the output as pd_series is of type pandas.core.series.Series. And also we can see the random value at index 0 of the series.

import pandas as pd
import numpy as np
nd_array = np.random.rand(4,2)
pd_series = pd.Series(np_array)
print(type(pd_series))
print(pd_series[0])

Output:

<class 'pandas.core.series.Series'>
0.7916550309100095

What is the difference in array and series

From the above example and output, we don’t see much difference between ndarray and series. They look the same then what is the difference in array and series.

The array has fixed and numeric indexes which start from 0,1,2,3….
But in series we have the numeric indexes and if we want we can also set the index of our choice. Let us understand this with an example:

import pandas as pd
import numpy as np
np_array = np.random.rand(4)
pd_series = pd.Series(np_array,index=["zero","one","two","three"])
print(pd_series,'\n')
print(pd_series["zero"])
print(pd_series[0])


Output:

As you can see number index still works and also our own index also works on series.

zero     0.411261
one      0.644768
two      0.350842
three    0.565235
dtype: float64 

0.4112614144776182
0.4112614144776182

Get Index of panda series

So for a given panda series if we want we can check the index by using index property like below:

import pandas as pd
import numpy as np
np_array = np.random.rand(4)
pd_series = pd.Series(np_array,index=["zero","one","two","three"])
print(pd_series.index)

Output:

Index(['zero', 'one', 'two', 'three'], dtype='object')

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