owaisqayum
Filtering list of lists
I am having a list of lists and i want to obtain an output by filtering them.
list =
[
[[key: 1, value: 2], [key: 1, value: 2]],
[[key: 1, value: 2], [key: 2, value: 3]],
[[key: 2, value: 3], [key: 1, value: 2]],
[[key: 2, value: 3], [key: 2, value: 3]]
]
here In each list i want to filter out those values where the keys are equal.
For example, in first list we have
[[key: 1, value: 2], [key: 1, value: 2]]
here both keys are equal, so how can we filter only those results where both the keys are equal.
Thanks
Marked As Solved
owaisqayum
So i have worked on it and found the solution for it
defmodule J do
def join(list_of_lists) do
join_single_row(list_of_lists, [])
|> Enum.map(fn row -> List.flatten(row) end)
end
def join_single_row([], final), do: final
def join_single_row([row | rest_of_rows], final) do
length =
Enum.map(row, fn [key, _value] -> key end)
|> Enum.uniq()
|> length()
case length do
1 ->
join_single_row(rest_of_rows, final ++ [row])
_ ->
join_single_row(rest_of_rows, final)
end
end
end
Also Liked
gregvaughn
iex(5)> list =
...(5)> [
...(5)> [[key: 1, value: 2], [key: 1, value: 2]],
...(5)> [[key: 1, value: 2], [key: 2, value: 3]],
...(5)> [[key: 2, value: 3], [key: 1, value: 2]],
...(5)> [[key: 2, value: 3], [key: 2, value: 3]]
...(5)> ]
iex(6)> for [left, right] = row <- list, left[:key] == right[:key], do: row
[
[[key: 1, value: 2], [key: 1, value: 2]],
[[key: 2, value: 3], [key: 2, value: 3]]
]
kokolegorille
Using Enum.map with Enum.filter would have worked too…
Please note that [key: :value] is a Keyword list… a special kind of list.
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