Python | Pandas Series.argsort ()

Michael Zippo 18.07.2021

Pandas Series.argsort () can be used to sort series items in pandas. But the main thing in the series of pandas — this is what we get the output as index values  of the sorted items in the series. In a later code demo, we’ll explain how we get the output as sorted index values .

Syntax: pandas.Series.argsort (axis = 0, kind = ’quicksort’, order = None)

Parameters:
axis: It is useful for numpy.
kind: {’mergesort’, ’quicksort’, ’heapsort’}, default ’quicksort’
order: It is useful for numpy.
Returns: argsorted Series, with -1 indicated where nan values are present

To get a link to the CSV file, click on nba.csv

Code # 1:
In this code, you will see that we take a simple series of some integer values and try to sort based on different sorting algorithms like quicksort, and merge heapsort , but by default it will accept the sort. Let’s see the code below and the following output.

# pandas import

import pandas as pd

# read CSV

data = pd. read_csv ( "nba.csv" )

data.dropna (inplace = True )

# create a series form weight column

g = pd.Series (data [ ’ Weight ’ ]. head ())

print (g)

gfg = g.argsort (axis = 0 , kind = ’quicksort’ , order = None )

print (gfg)

Exit:

 0 180.0 1 235.0 3 185.0 6 235.0 7 238.0 Name: Weight, dtype: float64 0 0 1 2 3 1 6 3 7 4 Name: Weight, dtype: int64

As you can see in the output, and it looks strange that instead of getting sorted values sequentially oh why we got these numbers. This is the basic concept of the Series.argsort () method it returns the index value of the smallest number first and the index value of the largest value at the end. Since we have 1 — this is the smallest number and its index value is 4, then it will be 4 first, and this concept will look like a stream following the output.

Code # 2:

       # pandas import  
   import   pandas as pd 
   
  # read CSV  
   data   =   pd.read_csv ( " nba.csv " ) 
    
   data.dropna (inplace   =   True  ) 
    
  # create a series form weight column  
   g   =   pd.Series (data [  ’Weight’  ]. Head ()) 
   print   (g) 
   
   gfg   =   g.argsort (axis   =   0  , kind   =  ’ mergesort’  , order   =   None  )  
   
   print   (gfg)

Exit:

 0 180.0 1 235.0 3 185.0 6 235.0 7 238.0 Name: Weight, dtype: float64 0 0 1 2 3 1 6 3 7 4 Name: Weight, dtype: int64    Code # 3:  
  
 
        # pandas import  
   import   pandas as pd 
   
  # read CSV  
   data   =   pd.read_csv (  "nba.csv"  ) 
   
   data.dropna (inplace   =   True  ) 
   
  # create series form weight column  
   g   =   pd.Series (data [  ’Weight’  ]. head ()) 
   print   (g)  
   
   gfg   =   g.argsort (axis   =   0  , kind   =   ’heapsort’  , order   =   None  ) 
   
   print   (gfg)  
  
 
 
    Exit:
  0 180.0 1 235.0 3 185.0 6 235.0 7 238.0 Name: Weight, dtype: float64 0 0 1 2 3 1 6 3 7 4 Name: Weight, dtype: int64 
   What is displayed when we have missing values?  
  As we explained above, if we want to handle missing values it will give -1 instead of  None . 
  
 
        import   pandas as pd 
   
  # pandas import  
   import   pandas as pd 
   
  # CSV reading  
   data   =   pd.read_csv (  "nba.csv"  )  
   
  # create series form weight column  
   g   =   pd.Series (data [  ’Weight ’ ]) 
   print   (g) 
   
   gfg   =   g.argsort (axis   =   0  , kind   =   ’mergesort’  , order   =   None  ) 
   
   print   (gfg) 
   Output:  
  450 226.0 451 206.0 452 234.0 453 203.0 454 179.0 455 256.0 456 231.0 457 NaN Name: Weight, Length: 458, dtype: float64 450 237 451 41 452 188 453 395 454 330 455 302 456 405 457 -1 Name: Weight, Length: 458, dtype: int64