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Pandas: Construct a series using the MultiIndex levels

Pandas Indexing: Exercise-12 with Solution

Write a Pandas program to construct a series using the MultiIndex levels as the column and index.

Sample Solution:

Python Code :

import pandas as pd 
import numpy as np
sales_arrays = [['sale1', 'sale1', 'sale2', 'sale2', 'sale3', 'sale3', 'sale4', 'sale4'],
          ['city1', 'city2', 'city1', 'city2', 'city1', 'city2', 'city1', 'city2']]
sales_tuples = list(zip(*sales_arrays))
print("Create a MultiIndex:")
sales_index = pd.MultiIndex.from_tuples(sales_tuples, names=['sale', 'city'])
print(sales_tuples)
print("\nConstruct a series using the said MultiIndex levels: ")
s = pd.Series(np.random.randn(8), index = sales_index)
print(s)

Sample Output:

Create a MultiIndex:
[('sale1', 'city1'), ('sale1', 'city2'), ('sale2', 'city1'), ('sale2', 'city2'), ('sale3', 'city1'), ('sale3', 'city2'), ('sale4', 'city1'), ('sale4', 'city2')]

Construct a series using the said MultiIndex levels: 
sale   city 
sale1  city1   -1.533805
       city2   -1.546815
sale2  city1    0.018307
       city2   -0.210834
sale3  city1    0.903430
       city2    1.269479
sale4  city1   -0.550486
       city2    1.738659
dtype: float64

Python Code Editor:


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Previous: Write a Pandas program to check if a specified value exists in single and multiple column index dataframe.

Next: Write a Pandas program to construct a DataFrame using the MultiIndex levels as the column and index.

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Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os
cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

  • The os and os.path modules.
  • The __file__ constant
  • os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
  • os.path.dirname(path) (returns "the directory name of pathname path")
  • os.getcwd() (returns "a string representing the current working directory")
  • os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m