Haskell search an element on a List
- by user1887556
I want a function that changes (1 to 0) on a list, when number of 1's isn't even. I have done these functions:
1) Sees if the lines in a list are even or not:
parityLine :: [[Int]] -> [Bool]
parityLine [] =[]
parityLine (x:xs)
|sum(x) `mod` 2 == 0 = True:(parityLine(xs))
|otherwise = False:(parityLine(xs))
2) Sum the corresponding elements on a list of lists:
sumPositions :: [[Int]] -> [Int]
sumPositions [] = []
sumPositions (x:xs) = foldl (zipWith (+)) (repeat 0) (x:xs)
3) Sees if the columns in a list are even or not:
parityColumn :: [Int] -> [Bool]
parityColumn [] = []
parityColumn (x:xs)
|head(x:xs) `mod` 2 == 0 = True:parityColumn(xs)
|otherwise = False:parityColumn(xs)
4) Does the operation or with two boolean lists:
bol :: [Bool] -> [Bool] -> [[Bool]]
bol [] _ = []
bol (x:xs) (y:ys)= (map (||x) (y:ys)):(bol xs (y:ys))
5) Correct List:
correct :: [[Int]] -> [[Bool]]
correct [] = []
correct (x:xs)=(bol(parityLine (x:xs))(parityColumn(sumPositions(x:xs))))
So what I want is to alter the function correct to [[Int]]-[[Int]] that does this:
My Int list(x:xs) With my correct function applied
[[0,0,1,1], [[True,True,False,True],
[1,0,1,1], [True,True,True,True],
[0,1,0,1], [True,True,True,True]
[1,1,1,1]] [True,True,True,True]]
Now I can see that in the first line third column, False, so I have to correct that number 1 to have a number of 1's even.
Result I want that function correct does:
[[0,0,0,1],
[1,0,1,1],
[0,1,0,1],
[1,1,1,1]]
Thanks.
