[Tutor] list generation

[Peter Otten]

On 11/05/2021 10:47, Alan Gauld wrote:
> 
> On 11/05/2021 01:12, Ed Connell wrote:
>> Thanks for your help. (All)
>>
>> I was working with  'map' and the function that it was mapping needed
>> 2 arguments.  The first was a list of values.  The second was always
>> the same - like 2.  Thus I needed a list of 2s or whatever at least as
>> long as the first list.  (Like [ 2, 2, ...2 ])  Of course I could use
>> a simple loop.  Then I hit on [ 2 for _ in range( length ) .  But I
>> like yours best - [ 2 ] * length.  Thanks again.
> 
> The usual way I'd solve that is to use a lambda expression:
> 
> result = map(lambda x: foo(x,2), collection)

For completeness I'd like to mention what has become the most common way 
to spell this in Python:

result = [foo(x, 2) for x in collection]

> Which will call the lamba with x from collection.
> 
> Then the lambda calls foo() with x as the first and 2 as the second
> argument.