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I have a csv file

1 , name , 1012B-Amazon , 2044C-Flipcart , Bosh27-Walmart
2 , name , Kelvi20-Flipcart, LG-Walmart   
3,  name , Kenstar-Walmart, Sony-Amazon , Kenstar-Flipcart
4, name ,  LG18-Walmart, Bravia-Amazon

I need the rows to be rearranged by the websites ie the part after -;

1, name , 1012B-Amazon , 2044C-Flipcart , Bosh27-Walmart
2, name ,              , Kelv20-Flipcart, LG-Walmart
3, name , Sony-Amazon,  Kenstar-Flipcart ,Kenstar-Walmart
4, name , Bravia-Amazon,                 ,LG18-Walmart 

Is it possible using pandas ? Finding the existence of a sting and re arrange it and iterate through all rows and repeat this for the next string ? I went through the documentation of Series.str.contains and str.extract but was unable to find a solution .

Anoop D
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3 Answers3

1

Using sorted with key

df.iloc[:,1:].apply(lambda x : sorted(x,key=lambda y: (y=='',y)),1)
     2    3    4    5
1  ABC  DEF  GHI  JKL
2  ABC  DEF  GHI     
3  ABC  DEF  GHI  JKL
#df.iloc[:,1:]=df.iloc[:,1:].apply(lambda x : sorted(x,key=lambda y: (y=='',y)),1)

Since you mention reindex I think get_dummies will work

s=pd.get_dummies(df.iloc[:,1:],prefix ='',prefix_sep='')
s=s.drop('',1)
df.iloc[:,1:]=s.mul(s.columns).values
df
      1    2    3    4    5
1  name  ABC  DEF  GHI  JKL
2  name  ABC  DEF  GHI     
3  name  ABC  DEF  GHI  JKL
BENY
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  • I am getting the error `TypeError: ("'<' not supported between instances of 'float' and 'str'", 'occurred at index 0') ` Sorry i am a python newbie – Anoop D Dec 08 '18 at 18:01
  • @AnoopD you have NaN do with df=df.fillna('') – BENY Dec 08 '18 at 18:01
  • `df1=df.iloc[:,1:].apply(lambda x : sorted(x,key=lambda y: (y=='',y)),1) ` ` df1` `0 [ ABC, DEF, ]` `1 [ ABC, DEF, GHI]` `dtype: object` – Anoop D Dec 08 '18 at 18:03
  • `ValueError: could not broadcast input array from shape (2,5) into shape (2,3)` . I used the first df . – Anoop D Dec 08 '18 at 18:06
  • @AnoopD it is work on my side . Maybe try to ready your dataframe into pandas and show dataframe to us ? – BENY Dec 08 '18 at 18:07
1

Assuming the empty value is np.nan:

# Fill in the empty values with some string to allow sorting
df.fillna('NaN', inplace=True)

# Flatten the dataframe, do the sorting and reshape back to a dataframe
pd.DataFrame(list(map(sorted, df.values)))

     0    1    2    3
0  ABC  DEF  GHI  JKL
1  ABC  DEF  GHI  NaN
2  ABC  DEF  GHI  JKL

UPDATE

Given the update to the question and the sample data being as follows

df = pd.DataFrame({'name': ['name1', 'name2', 'name3', 'name4'],
                   'b': ['1012B-Amazon', 'Kelvi20-Flipcart', 'Kenstar-Walmart', 'LG18-Walmart'],
                   'c': ['2044C-Flipcart', 'LG-Walmart', 'Sony-Amazon', 'Bravia-Amazon'],
                   'd': ['Bosh27-Walmart', np.nan, 'Kenstar-Flipcart', np.nan]})

a possible solution could be

def foo(df, retailer):

    # Find cells that contain the name of the retailer
    mask = df.where(df.apply(lambda x: x.str.contains(retailer)), '')

    # Squash the resulting mask into a series
    col = mask.max(skipna=True, axis=1)

    # Optional: trim the name of the retailer
    col = col.str.replace(f'-{retailer}', '')
    return col

df_out = pd.DataFrame(df['name'])
for retailer in ['Amazon', 'Walmart', 'Flipcart']:
    df_out[retailer] = foo(df, retailer)

resulting in

    name  Amazon  Walmart Flipcart
0  name1   1012B   Bosh27    2044C
1  name2               LG  Kelvi20
2  name3    Sony  Kenstar  Kenstar
3  name4  Bravia     LG18         
ayorgo
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  • Sorry that doesn't work that way , the data given are only dummy data and that does not have any sortable order . What i need is using `regex` i have to find the occurrences in each row and reorder them . – Anoop D Dec 08 '18 at 18:31
  • What is the rule you want to rearrange your data by then if it's not alphabetical sorting? – ayorgo Dec 08 '18 at 18:33
  • Think pandas `Series.str.contains` will work , but i am not sure ...... – Anoop D Dec 08 '18 at 18:35
  • Can you please be more specific? Find occurrences of what with regex? Reorder rows how exactly? – ayorgo Dec 08 '18 at 18:38
  • `1, W/M , 1012B-Amazon , 2044C-Flipcart , Bosh27-Walmart` `2, R/F , Kelvi20-Flipcart, LG-Walmart` `3, E/O , Kenstar-Walmart , Sony-Amazon , Kenstar-Flipcart` I need these to be re ordered as `1, W/M , 1012B-Amazon , 2044C-Flipcart , Bosh27-Walmart` `2, R/F , ,Kelvi20-Flipcart, LG-Walmart` `3, E/O , Sony-Amazon , Kenstar-Flipcart` ,Kenstar-Walmart ` – Anoop D Dec 08 '18 at 18:44
  • Sorry, but from what you've posted I can't deduce any rule that transforms one into the other. It's certainly not alphabetical. The first two rows go unchanged but the third one comes in a different order. Can you please clarify why `Kenstar-Walmart` should come after `Kenstar-Flipcart` for example? – ayorgo Dec 08 '18 at 19:24
  • Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/184945/discussion-between-anoop-d-and-ayorgo). – Anoop D Dec 09 '18 at 00:52
1

Edit after Question Update:

This is the abc csv:

1,name,ABC,GHI,DEF,JKL
2,name,GHI,DEF,ABC,
3,name,JKL,GHI,ABC,DEF

This is the company csv (it is necessary to watch the commas carefully):

1,name,1012B-Amazon,2044C-Flipcart,Bosh27-Walmart
2,name,Kelvi20-Flipcart,LG-Walmart,
3,name,Kenstar-Walmart,Sony-Amazon,Kenstar-Flipcart
4,name,LG18-Walmart,Bravia-Amazon,

Here is the code

import pandas as pd
import numpy as np


#These solution assume that each value that is not empty is not repeated
#within each row. If that is not the case for your data, it would be possible
#to do some transformations that the non empty values are unique for each row.    

#"get_company" returns the company if the value is non-empty and an
#empty value if the value was empty to begin with:
def get_company(company_item):
    if pd.isnull(company_item):
        return np.nan
    else:
        company=company_item.split('-')[-1]
        return company

#Using the "define_sort_order" function, one can retrieve a template to later
#sort all rows in the sort_abc_rows function. The template is derived from all
#values, aside from empty values, within the matrix when "by_largest_row" = False.
#One could also choose the single largest row to serve as the
#template for all other rows to follow. Both options work similarly when
#all rows are subsets of the largest row i.e. Every element in every
#other row (subset) can be found in the largest row (or set)

#The difference relates to, when the items contain unique elements,
#Whether one wants to create a table with all sorted elements serving
#as the columns, or whether one wants to simply exclude elements
#that are not in the largest row when at least one non-subset row does not exist 

#Rather than only having the application of returning the original data rows,
#one can get back a novel template with different values from that of the
#original dataset if one uses a function to operate on the template

def define_sort_order(data,by_largest_row = False,value_filtering_function = None):
    if not by_largest_row: 
        if value_filtering_function:
            data = data.applymap(value_filtering_function)
        #data.values returns a numpy array                 
        #with rows and columns. .flatten()
        #puts all elements in a 1 dim array
        #set gets all unique values in the array
        filtered_values = list(set((data.values.flatten())))
        filtered_values = [data_value for data_value in filtered_values if not_empty(data_value)]
        #sorted returns a list, even with np.arrays as inputs

        model_row = sorted(filtered_values)
    else:
        if value_filtering_function:
            data = data.applymap(value_filtering_function)
        row_lengths = data.apply(lambda data_row: data_row.notnull().sum(),axis = 1)
        #locates the numerical index for the row with the most non-empty elements:
        model_row_idx = row_lengths.idxmax()
    #sort and filter the row with the most values:
        filtered_values = list(set(data.iloc[model_row_idx]))

        model_row = [data_value for data_value in sorted(filtered_values) if not_empty(data_value)] 

    return model_row

#"not_empty" is used in the above function in order to filter list models that
#they no empty elements remain
def not_empty(value):
    return pd.notnull(value) and value not in ['','  ',None]

#Sorts all element in each _row within their corresponding position within the model row.
#elements in the model row that are missing from the current data_row are replaced with np.nan

def reorder_data_rows(data_row,model_row,check_by_function=None):
    #Here, we just apply the same function that we used to find the sorting order that
    #we computed when we originally #when we were actually finding the ordering of the model_row.
    #We actually transform the values of the data row temporarily to determine whether the
    #transformed value is in the model row. If so, we determine where, and order #the function
    #below in such a way.
    if check_by_function: 
        sorted_data_row = [np.nan]*len(model_row) #creating an empty vector that is the
                          #same length as the template, or model_row

        data_row = [value for value in data_row.values if not_empty(value)]

        for value in data_row:
            value_lookup = check_by_function(value)
            if value_lookup in model_row:
                idx = model_row.index(value_lookup)
                #placing company items in their respective row positions as indicated by
        #the model_row                #
                sorted_data_row[idx] = value    
    else:
        sorted_data_row = [value if value in data_row.values else np.nan for value in model_row]
    return pd.Series(sorted_data_row)

##################### ABC ######################
#Reading the data:
#the file will automatically include the header as the first row if this the  
#header = None option is not included. Note: "name" and the 1,2,3 columns are not in the index.
abc = pd.read_csv("abc.csv",header = None,index_col = None)
# Returns a sorted, non-empty list. IF you hard code the order you want,
# then you can simply put the hard coded order in the second input in model_row and avoid
# all functions aside from sort_abc_rows.
model_row = define_sort_order(abc.iloc[:,2:],False)

#applying the "define_sort_order" function we created earlier to each row before saving back into
#the original dataframe
#lambda allows us to create our own function without giving it a name.
#it is useful in this circumstance in order to use two inputs for sort_abc_rows


abc.iloc[:,2:] = abc.iloc[:,2:].apply(lambda abc_row: reorder_data_rows(abc_row,model_row),axis = 1).values

#Saving to a new csv that won't include the pandas created indices (0,1,2)
#or columns names (0,1,2,3,4):

abc.to_csv("sorted_abc.csv",header = False,index = False)
################################################


################## COMPANY #####################
company = pd.read_csv("company.csv",header=None,index_col=None)

model_row = define_sort_order(company.iloc[:,2:],by_largest_row = False,value_filtering_function=get_company)
#the only thing that changes here is that we tell the sort function what specific
#criteria to use to reorder each row by. We're using the result from the
#get_company function to do so. The custom function get_company, takes an input
#such as Kenstar-Walmart, and outputs Walmart (what's after the "-").
#we would then sort by the resulting list of companies. 

#Because we used the define_sort_order function to retrieve companies rather than company items in order,
#We need to use the same function to reorder each element in the DataFrame
company.iloc[:,2:] = company.iloc[:,2:].apply(lambda companies_row: reorder_data_rows(companies_row,model_row,check_by_function=get_company),axis=1).values
company.to_csv("sorted_company.csv",header = False,index = False)
#################################################

Here is the first result from sorted_abc.csv:

1  name  ABC  DEF  GHI  JKL
2  name  ABC  DEF  GHI  NaN
3  name  ABC  DEF  GHI  JKL

After modifying the code to the subsequent form inquired about, here is the sorted_company.csv that resulted from running the script.

1  name    1012B-Amazon    2044C-Flipcart   Bosh27-Walmart
2  name             NaN  Kelvi20-Flipcart       LG-Walmart
3  name     Sony-Amazon  Kenstar-Flipcart  Kenstar-Walmart
4  name   Bravia-Amazon               NaN     LG18-Walmart

I hope it helps!

I Bajwa PHD
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