How to create multiple dataframes using multiple functions - python-3.x

Question

I quite often write a function to return different dataframes based on the parameters I enter. Here's an example dataframe:
np.random.seed(1111)
df = pd.DataFrame({
'Category':np.random.choice( ['Group A','Group B','Group C','Group D'], 10000),
'Sub-Category':np.random.choice( ['X','Y','Z'], 10000),
'Sub-Category-2':np.random.choice( ['G','F','I'], 10000),
'Product':np.random.choice( ['Product 1','Product 2','Product 3'], 10000),
'Units_Sold':np.random.randint(1,100, size=(10000)),
'Dollars_Sold':np.random.randint(100,1000, size=10000),
'Customer':np.random.choice(pd.util.testing.rands_array(10,25,dtype='str'),10000),
'Date':np.random.choice( pd.date_range('1/1/2016','12/31/2018',
freq='M'), 10000)})
I then created a function to perform sub-totals for me like this:
def some_fun(DF1, agg_column, myList=[], *args):
y = pd.concat([
DF1.assign(**{x:'[Total]' for x in myList[i:]})\
.groupby(myList).agg(sumz = (agg_column,'sum')) for i in range(1,len(myList)+1)]).sort_index().unstack(0)
return y
I then write out lists that I'll pass as arguments to the function:
list_one = [pd.Grouper(key='Date',freq='A'),'Category','Product']
list_two = [pd.Grouper(key='Date',freq='A'),'Category','Sub-Category','Sub-Category-2']
list_three = [pd.Grouper(key='Date',freq='A'),'Sub-Category','Product']
I then have to run each list through my function creating new dataframes:
df1 = some_fun(df,'Units_Sold',list_one)
df2 = some_fun(df,'Dollars_Sold',list_two)
df3 = some_fun(df,'Units_Sold',list_three)
I then use a function to write each of these dataframes to an Excel worksheet. This is just an example - I perform this same exercise 10+ times.
My question - is there a better way to perform this task than to write out df1, df2, df3 with the function information applied? Should I be looking at using a dictionary or some other data type to do this my pythonically with a function?

Answer 1

A dictionary would be my first choice:
variations = ([('Units Sold', list_one), ('Dollars_Sold',list_two),
..., ('Title', some_list)])
df_variations = {}
for i, v in enumerate(variations):
name = v[0]
data = v[1]
df_variations[i] = some_fun(df, name, data)
You might further consider setting the keys to unique / helpful titles for the variations, that goes beyond something like 'Units Sold', which isn't unique in your case.

Answer 2

IIUC,
as Thomas has suggested we can use a dictionary to parse through your data, but with some minor modifications to your function, we can use the dictionary to hold all the required data then pass that through to your function.
the idea is to pass two types of keys, the list of columns and the arguments to your pd.Grouper call.
data_dict = {
"Units_Sold": {"key": "Date", "freq": "A"},
"Dollars_Sold": {"key": "Date", "freq": "A"},
"col_list_1": ["Category", "Product"],
"col_list_2": ["Category", "Sub-Category", "Sub-Category-2"],
"col_list_3": ["Sub-Category", "Product"],
}
def some_fun(dataframe, agg_col, dictionary,column_list, *args):
key = dictionary[agg_col]["key"]
frequency = dictionary[agg_col]["freq"]
myList = [pd.Grouper(key=key, freq=frequency), *dictionary[column_list]]
y = (
pd.concat(
[
dataframe.assign(**{x: "[Total]" for x in myList[i:]})
.groupby(myList)
.agg(sumz=(agg_col, "sum"))
for i in range(1, len(myList) + 1)
]
)
.sort_index()
.unstack(0)
)
return y
Test.
df1 = some_fun(df,'Units_Sold',data_dict,'col_list_3')
print(df1)
sumz
Date 2016-12-31 2017-12-31 2018-12-31
Sub-Category Product
X Product 1 18308 17839 18776
Product 2 18067 19309 18077
Product 3 17943 19121 17675
[Total] 54318 56269 54528
Y Product 1 20699 18593 18103
Product 2 18642 19712 17122
Product 3 17701 19263 20123
[Total] 57042 57568 55348
Z Product 1 19077 17401 19138
Product 2 17207 21434 18817
Product 3 18405 17300 17462
[Total] 54689 56135 55417
[Total] [Total] 166049 169972 165293
as you want to automate the writing of the 10x worksheets, we can again do that with a dictionary call over your function:
matches = {'Units_Sold': ['col_list_1','col_list_3'],
'Dollars_Sold' : ['col_list_2']}
then a simple for loop to write all the files to a single excel sheet, change this to match your required behavior.
writer = pd.ExcelWriter('finished_excel_file.xlsx')
for key,value in matches.items():
for items in value:
dataframe = some_fun(df,k,data_dict,items)
dataframe.to_excel(writer,f'{key}_{items}')
writer.save()