[Haskell-beginners] Padding List with Zeros
Lorenzo Isella
lorenzo.isella at gmail.com
Tue Sep 14 19:35:06 EDT 2010
Dear All,
I still have to find my way with immutable lists and list comprehension.
Consider the following lists
A=[0,10,20,30,40,50]
B=[0,10,50] (i.e. B is a subset of list A; list A is already ordered in
increasing order and so is B).
C=[2,1,-5] i.e. there is a corresponding element in C for every element
in B.
Now, I would like to define a new list D having length equal to the
length of A. The elements of D in the position of the elements of A in
common with B are equal to the corresponding entries in C, whereas the
other ones are zero i.e.
D=[2,1,0,0,0,-5]. How can I achieve that? The first thought that comes
to my mind is to define a list of zeros which I would modify according
to my needs, but that is not allowed...
Many thanks
Lorenzo
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