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@ijoshsmith
Created April 20, 2016 20:12
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Weather Data kata in Elixir
Dy MxT MnT AvT HDDay AvDP 1HrP TPcpn WxType PDir AvSp Dir MxS SkyC MxR MnR AvSLP
1 88 59 74 53.8 0.00 F 280 9.6 270 17 1.6 93 23 1004.5
2 79 63 71 46.5 0.00 330 8.7 340 23 3.3 70 28 1004.5
3 77 55 66 39.6 0.00 350 5.0 350 9 2.8 59 24 1016.8
4 77 59 68 51.1 0.00 110 9.1 130 12 8.6 62 40 1021.1
5 90 66 78 68.3 0.00 TFH 220 8.3 260 12 6.9 84 55 1014.4
6 81 61 71 63.7 0.00 RFH 030 6.2 030 13 9.7 93 60 1012.7
7 73 57 65 53.0 0.00 RF 050 9.5 050 17 5.3 90 48 1021.8
8 75 54 65 50.0 0.00 FH 160 4.2 150 10 2.6 93 41 1026.3
9 86 32* 59 6 61.5 0.00 240 7.6 220 12 6.0 78 46 1018.6
10 84 64 74 57.5 0.00 F 210 6.6 050 9 3.4 84 40 1019.0
11 91 59 75 66.3 0.00 H 250 7.1 230 12 2.5 93 45 1012.6
12 88 73 81 68.7 0.00 RTH 250 8.1 270 21 7.9 94 51 1007.0
13 70 59 65 55.0 0.00 H 150 3.0 150 8 10.0 83 59 1012.6
14 61 59 60 5 55.9 0.00 RF 060 6.7 080 9 10.0 93 87 1008.6
15 64 55 60 5 54.9 0.00 F 040 4.3 200 7 9.6 96 70 1006.1
16 79 59 69 56.7 0.00 F 250 7.6 240 21 7.8 87 44 1007.0
17 81 57 69 51.7 0.00 T 260 9.1 270 29* 5.2 90 34 1012.5
18 82 52 67 52.6 0.00 230 4.0 190 12 5.0 93 34 1021.3
19 81 61 71 58.9 0.00 H 250 5.2 230 12 5.3 87 44 1028.5
20 84 57 71 58.9 0.00 FH 150 6.3 160 13 3.6 90 43 1032.5
21 86 59 73 57.7 0.00 F 240 6.1 250 12 1.0 87 35 1030.7
22 90 64 77 61.1 0.00 H 250 6.4 230 9 0.2 78 38 1026.4
23 90 68 79 63.1 0.00 H 240 8.3 230 12 0.2 68 42 1021.3
24 90 77 84 67.5 0.00 H 350 8.5 010 14 6.9 74 48 1018.2
25 90 72 81 61.3 0.00 190 4.9 230 9 5.6 81 29 1019.6
26 97* 64 81 70.4 0.00 H 050 5.1 200 12 4.0 107 45 1014.9
27 91 72 82 69.7 0.00 RTH 250 12.1 230 17 7.1 90 47 1009.0
28 84 68 76 65.6 0.00 RTFH 280 7.6 340 16 7.0 100 51 1011.0
29 88 66 77 59.7 0.00 040 5.4 020 9 5.3 84 33 1020.6
30 90 45 68 63.6 0.00 H 240 6.0 220 17 4.8 200 41 1022.7
mo 82.9 60.5 71.7 16 58.8 0.00 6.9 5.3
defmodule Weather do
def print(path) do
File.stream!(path)
|> Stream.map( &extract_row_from_line/1 )
|> Stream.map( &drop_unused_columns_from_row/1 )
|> Enum.map( &convert_strings_to_integers/1 )
|> Enum.filter( &is_day?/1 )
|> Enum.reduce( &row_with_smaller_temperature_spread/2 )
|> print_result
end
defp extract_row_from_line(line) do
String.split(line, " ", trim: true)
end
defp drop_unused_columns_from_row(row) do
Stream.take(row, 3) # Day, Max Temp, Min Temp
end
defp convert_strings_to_integers(row) do
row |> Enum.map(fn(str) ->
case Integer.parse(str) do
{int, _} -> int
:error -> :not_a_day
end
end)
end
defp is_day?([head | _]), do: head != :not_a_day
defp row_with_smaller_temperature_spread([_, max1, min1] = row1,
[_, max2, min2] = row2) do
if (max1 - min1) < (max2 - min2), do: row1, else: row2
end
defp print_result([day, max, min]) do
IO.puts("Day: #{day} High: #{max} Low: #{min}")
end
end
@ijoshsmith
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Code written based on the Weather Data kata, from http://codekata.com/kata/kata04-data-munging/

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