return value - python - getting 'none' at the end of printing a list -

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• extra output none while printing command line argument [duplicate] 2 answers

newbie here. can please explain me why 'none' printed @ end of code, when called inside function?

background: have variable (share_data) contains lists:

share_data =  [['date', 'ticker', 'company', 'mkt cap', 'vm rank', 'value rank', 'momentum rank'],   ['2016-08-27', 'bez', 'beazley', '2,063', '89', '72', '76'],  ['2016-08-30', 'bez', 'beazley', '2,063', '89', '72', '76'],  ['2016-08-31', 'bez', 'beazley', '2,050', '89', '72', '75'],  ['2016-09-01', 'bez', 'beazley', '2,039', '96', '73', '93'],  ['2016-09-02', 'bez', 'beazley', '2,069', '90', '72', '77'],  ['2016-09-03', 'bez', 'beazley', '2,120', '96', '70', '94'],  ['2016-09-06', 'bez', 'beazley', '2,106', '90', '71', '77'],  ['2016-09-07', 'bez', 'beazley', '2,085', '89', '71', '76'],  ['2016-09-08', 'bez', 'beazley', '2,091', '89', '72', '77'],  ['2016-09-09', 'bez', 'beazley', '2,114', '89', '71', '77'],  ['2016-09-10', 'bez', 'beazley', '2,084', '94', '71', '89'],  ['2016-09-12', 'bez', 'beazley', '2,084', '94', '71', '89']] 

i interested in printing last 5 lines.

if use in main program:

for row in share_data[-5:]:     print(row) 

i correct data:

['2016-09-07', 'bez', 'beazley', '2,085', '89', '71', '76'] ['2016-09-08', 'bez', 'beazley', '2,091', '89', '72', '77'] ['2016-09-09', 'bez', 'beazley', '2,114', '89', '71', '77'] ['2016-09-10', 'bez', 'beazley', '2,084', '94', '71', '89'] ['2016-09-12', 'bez', 'beazley', '2,084', '94', '71', '89'] 

...however when created function this:

def share_details(share_data, n=5):     ''' prints last n rows of share's records'''     row in share_data[-n:]:         print(row)     return 

and called function way:

print(share_details(share_data)) 

...what (note 'none' @ end):

['2016-09-07', 'bez', 'beazley', '2,085', '89', '71', '76'] ['2016-09-08', 'bez', 'beazley', '2,091', '89', '72', '77'] ['2016-09-09', 'bez', 'beazley', '2,114', '89', '71', '77'] ['2016-09-10', 'bez', 'beazley', '2,084', '94', '71', '89'] ['2016-09-12', 'bez', 'beazley', '2,084', '94', '71', '89'] none 

i think it's 'return' statement @ end of function triggers it, don't know how/why.

edit - that's it's clear error (ie. printing inside function, , return value outside) can follow additional question? is practice delegate printing function? maybe function called, readability:

print_share_details(share_data) 

or there better way more readable/pythonic?

when write print(share_details(share_data)) - means print value returned share_details function. function returns none after printing values.

if function doesn't return needs printed, better omit print , call function like:

share_details(share_data)