Heads-I-Lose

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Overview
Comment:Housekeeping: Formatting, variable naming consistency, etc - Get rid of the mixed up mess of CamelCase, underscores, prefixes, suffixes, abbreviations, full names, etc. - Make indenting of lists:map functions consistent - Remove spurious whitespace
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Timelines: family | ancestors | descendants | both | trunk | origin/master
Files: files | file ages | folders
SHA3-256: 301914a6a181661f7bdf5bb0ad9e430a1e2742ac50f07f9a7217f49158096477
User & Date: base@atomicules.co.uk 2014-12-05 20:43:53
Context
2014-12-05
23:51
Calculate wind-type percentages and use to determine win/lose In other words: done for now. Those are pretty much the changes I wanted to do. Sure they will be much room for improvements to the code, but it works! check-in: c4d0b2bbec user: base@atomicules.co.uk tags: trunk, origin/master
20:43
Housekeeping: Formatting, variable naming consistency, etc - Get rid of the mixed up mess of CamelCase, underscores, prefixes, suffixes, abbreviations, full names, etc. - Make indenting of lists:map functions consistent - Remove spurious whitespace check-in: 301914a6a1 user: base@atomicules.co.uk tags: trunk, origin/master
2014-11-30
11:02
Extend functionality to sum up all wind directions by mapping. Need to tidy up formatting and make it consistent and sort out the naming of variables - it's such a mess. check-in: 6912ce6208 user: base@atomicules.co.uk tags: trunk, origin/master
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to headsilose.erl.

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-import(weather_types, [weather_type/1]).
-import(polyline, [decode/1]).
-import(osrm, [read_route/0]).

%Supply a direction and location and work out if head wind or not
%For now "know the location id" upfront, but ideally need to search for it at some point or present a choice.

%Initially based on: http://pragdave.pragprog.com/pragdave/2007/04/a_first_erlang_.html 

-define(BASE_URL,
	"http://datapoint.metoffice.gov.uk/public/data/").

-define(WXFCS_SITELIST,
	"val/wxfcs/all/xml/sitelist").

................................................................................
	try
		{ ok, {_Status, _Headers, Body }} = httpc:request(get, {URL, []}, [{timeout, timer:seconds(10)}], []),
		{ Xml, _Rest } = xmerl_scan:string(Body),
		[ [ #xmlAttribute{value=Direction} ],
		  [ #xmlAttribute{value=Speed} ],
		  [ #xmlAttribute{value=Gust} ],
		  [ #xmlAttribute{value=Weather} ],
		  [ #xmlAttribute{value=Temperature} ] ] = lists:map(fun(X) ->

				xmerl_xpath:string("//Period[@value='" ++ Date_formatted ++ "']/Rep[.='" ++ Rep ++ "']/@"++X, Xml)
			end,
			["D", "S", "G", "W", "T"]),
		{Direction, Speed, Gust, Weather, Temperature}
	catch
		_:Reason ->
			io:format("API Might be down~n"),
................................................................................
	Rep = "360",
	{format_date(find_next_day(Date)), Rep}.


format_date(Date_to_format) ->
	{{Year, Month, Day}, {_Hours, _Minutes, _Seconds}} = Date_to_format,
	%Thanks to: http://stackoverflow.com/a/7599506/208793
	DateAsString = io_lib:format("~4..0w-~2..0w-~2..0wZ", [Year, Month, Day]),
	lists:flatten(DateAsString).


nth_wrap(N, List) ->
	Rem = N rem (length(List)),
	if Rem > 0 ->
		lists:nth(Rem, List);
	Rem =:= 0 ->
................................................................................


maybe_quit() ->
	Args = init:get_arguments(), 
	Found = lists:keyfind(noshell, 1, Args),
	if Found =:= false ->
		dont_quit;

	true -> init:stop()
	end.	


build_list_of_wind_directions(Wind_direction) ->
	%There is only one wind direction, but can build groups of directions that will count as head, side and tail winds
	Compass = ["N", "NNE", "NE", "ENE", "E", "ESE", "SE", "SSE", "S", "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW"],
	%Quicker dirtier(?) way to do below would be: http://stackoverflow.com/a/6762191/208793
	Index = length(lists:takewhile(fun(X) -> X  =/= Wind_direction end, Compass))+1,
	%Since heading is to direction and winds are from, opposite is -2 to +2, or to make it easier to wrap, +14 +18
	%Since heading is to direction and winds are from, sidewinds are -5 to -3 and +3 to +5, or to make it easier to wrap, +14 +18
	%And so on
	HeadwindList = lists:seq(14,18),
	SidewindList = lists:seq(3,5)++lists:seq(11,13),
	TailwindList = lists:seq(6,10),
	[Headwinds, Sidewinds, Tailwinds] = lists:map(fun(WindList) ->

		lists:map(fun(X) ->

			nth_wrap(Index+X, Compass) end,

			WindList)
		end,
		[HeadwindList, SidewindList, TailwindList]).



convert_lats_longs_to_distance_heading([_Head1 | [ _Head2 | Rest]])  -> 
	%All co-ords are diff, so just ignore first two
	convert_lats_longs_to_distance_heading_(Rest, []).
convert_lats_longs_to_distance_heading_([Lat | [Lon | Rest]], List_distance_headings) ->
	%Want to map through the list convert co-ords to distance and heading
	Distance = math:sqrt(math:pow(Lat,2) + math:pow(Lon,2)),
	Heading_signed = math:atan2(Lon, Lat),
	%Need to convert heading into a 2π value
	Heading = if Heading_signed < 0 ->
				Heading_signed + 2*math:pi();
			true ->
				Heading_signed
			end,
	Compass_direction = get_compass_direction_for(Heading),
	convert_lats_longs_to_distance_heading_(Rest, [{Distance, Compass_direction}]++List_distance_headings);
convert_lats_longs_to_distance_heading_([], List_distance_headings) ->
	lists:reverse(List_distance_headings).


get_compass_direction_for(Heading) ->
	%In a way this is a waste of time as could just do headwind, etc based on angles, but since already have some code, why not?
	Segment = 2*math:pi()/16,
	Segments = erlang:round(Heading/Segment),
	Compass = ["N", "NNE", "NE", "ENE", "E", "ESE", "SE", "SSE", "S", "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW"],
	lists:nth(Segments, Compass).


head_side_or_tail_wind(Direction, [Headwinds, Sidewinds, Tailwinds]) ->
	[Headwind, Sidewind, Tailwind] = lists:map(fun(Winds) ->

		lists:member(Direction, Winds) end,

		[Headwinds, Sidewinds, Tailwinds]),
	if Headwind ->
		headwind;
	Sidewind ->
		sidewind;
	Tailwind ->
		tailwind
................................................................................
	{Direction, Speed, Gust, Weather, Temperature} = get_weather(Location),
	Weather_type = weather_types:weather_type(erlang:list_to_integer(Weather)),
	[Headwinds, Sidewinds, Tailwinds] = build_list_of_wind_directions(Direction),
	%Ok so now map this list over (like previous function) the headings list to get list of head, side, tail and distances?

	{_Checksum, Polyline} = osrm:read_route(),
	Polyline_decoded = polyline:decode(Polyline),
	List_of_distances_and_compass = convert_lats_longs_to_distance_heading(Polyline_decoded),
	%If now have a set of co-ords need to figure out distances and directions

	List_of_distances_and_wind = lists:map(fun({Distance, Compass}) ->
			Wind = head_side_or_tail_wind(Compass, [Headwinds, Sidewinds, Tailwinds]),
			{Distance, Wind}
		end,
		List_of_distances_and_compass),
	[Headw, Sidew, Tailw] = lists:map(fun(Wind_group) ->



		lists:filter(fun({_Distance, Wind_type}) ->
			Wind_type == Wind_group end,

			List_of_distances_and_wind) end,

		[headwind, sidewind, tailwind]),
	[Sum_of_Headw, Sum_of_Sidew, Sum_of_Tailw] = lists:map(fun(Windg) ->
		lists:foldl(fun({Distance2, _Wind}, Sum) -> Distance2 + Sum end, 0, Windg) end,
		[Headw, Sidew, Tailw]).










	%io:format("Direction: ~s~nSpeed: ~s mph~nGust: ~s mph~nWeather type: ~s~nTemperature: ~s deg C~n", [Direction, Speed, Gust, Weather_type, Temperature]).


%Need to read API key from file
readapikey() ->
	{_Status, KeyB} = file:read_file(os:getenv("HOME") ++ "/.datapoint"),
	string:strip(erlang:binary_to_list(KeyB),right,$\n).







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-import(weather_types, [weather_type/1]).
-import(polyline, [decode/1]).
-import(osrm, [read_route/0]).

%Supply a direction and location and work out if head wind or not
%For now "know the location id" upfront, but ideally need to search for it at some point or present a choice.

%Initially based on: http://pragdave.pragprog.com/pragdave/2007/04/a_first_erlang_.html

-define(BASE_URL,
	"http://datapoint.metoffice.gov.uk/public/data/").

-define(WXFCS_SITELIST,
	"val/wxfcs/all/xml/sitelist").

................................................................................
	try
		{ ok, {_Status, _Headers, Body }} = httpc:request(get, {URL, []}, [{timeout, timer:seconds(10)}], []),
		{ Xml, _Rest } = xmerl_scan:string(Body),
		[ [ #xmlAttribute{value=Direction} ],
		  [ #xmlAttribute{value=Speed} ],
		  [ #xmlAttribute{value=Gust} ],
		  [ #xmlAttribute{value=Weather} ],
		  [ #xmlAttribute{value=Temperature} ] ] = lists:map(
			fun(X) ->
				xmerl_xpath:string("//Period[@value='" ++ Date_formatted ++ "']/Rep[.='" ++ Rep ++ "']/@"++X, Xml)
			end,
			["D", "S", "G", "W", "T"]),
		{Direction, Speed, Gust, Weather, Temperature}
	catch
		_:Reason ->
			io:format("API Might be down~n"),
................................................................................
	Rep = "360",
	{format_date(find_next_day(Date)), Rep}.


format_date(Date_to_format) ->
	{{Year, Month, Day}, {_Hours, _Minutes, _Seconds}} = Date_to_format,
	%Thanks to: http://stackoverflow.com/a/7599506/208793
	Date_as_string = io_lib:format("~4..0w-~2..0w-~2..0wZ", [Year, Month, Day]),
	lists:flatten(Date_as_string).


nth_wrap(N, List) ->
	Rem = N rem (length(List)),
	if Rem > 0 ->
		lists:nth(Rem, List);
	Rem =:= 0 ->
................................................................................


maybe_quit() ->
	Args = init:get_arguments(), 
	Found = lists:keyfind(noshell, 1, Args),
	if Found =:= false ->
		dont_quit;
	true ->
		init:stop()
	end.


build_list_of_wind_directions(Wind_direction) ->
	%There is only one wind direction, but can build groups of directions that will count as head, side and tail winds
	Compass = ["N", "NNE", "NE", "ENE", "E", "ESE", "SE", "SSE", "S", "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW"],
	%Quicker dirtier(?) way to do below would be: http://stackoverflow.com/a/6762191/208793
	Index = length(lists:takewhile(fun(X) -> X  =/= Wind_direction end, Compass))+1,
	%Since heading is to direction and winds are from, opposite is -2 to +2, or to make it easier to wrap, +14 +18
	%Since heading is to direction and winds are from, sidewinds are -5 to -3 and +3 to +5, or to make it easier to wrap, +14 +18
	%And so on
	Headwind_list = lists:seq(14,18),
	Sidewind_list = lists:seq(3,5)++lists:seq(11,13),
	Tailwind_list = lists:seq(6,10),
	lists:map(
		fun(Wind_list) ->
			lists:map(
				fun(X) ->
					nth_wrap(Index+X, Compass)
				end,
				Wind_list)
		end,

		[Headwind_list, Sidewind_list, Tailwind_list]).


convert_lats_longs_to_distance_heading([_Head1 | [ _Head2 | Rest]])  -> 
	%All co-ords are diff, so just ignore first two
	convert_lats_longs_to_distance_heading_(Rest, []).
convert_lats_longs_to_distance_heading_([Lat | [Lon | Rest]], Distance_headings_list) ->
	%Want to map through the list convert co-ords to distance and heading
	Distance = math:sqrt(math:pow(Lat,2) + math:pow(Lon,2)),
	Heading_signed = math:atan2(Lon, Lat),
	%Need to convert heading into a 2π value
	Heading = if Heading_signed < 0 ->
				Heading_signed + 2*math:pi();
			true ->
				Heading_signed
			end,
	Compass_direction = get_compass_direction_for(Heading),
	convert_lats_longs_to_distance_heading_(Rest, [{Distance, Compass_direction}]++Distance_headings_list);
convert_lats_longs_to_distance_heading_([], Distance_headings_list) ->
	lists:reverse(Distance_headings_list).


get_compass_direction_for(Heading) ->
	%In a way this is a waste of time as could just do headwind, etc based on angles, but since already have some code, why not?
	Segment = 2*math:pi()/16,
	Segments = erlang:round(Heading/Segment),
	Compass = ["N", "NNE", "NE", "ENE", "E", "ESE", "SE", "SSE", "S", "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW"],
	lists:nth(Segments, Compass).


head_side_or_tail_wind(Direction, [Headwinds, Sidewinds, Tailwinds]) ->
	[Headwind, Sidewind, Tailwind] = lists:map(
		fun(Winds) ->
			lists:member(Direction, Winds)
		end,
		[Headwinds, Sidewinds, Tailwinds]),
	if Headwind ->
		headwind;
	Sidewind ->
		sidewind;
	Tailwind ->
		tailwind
................................................................................
	{Direction, Speed, Gust, Weather, Temperature} = get_weather(Location),
	Weather_type = weather_types:weather_type(erlang:list_to_integer(Weather)),
	[Headwinds, Sidewinds, Tailwinds] = build_list_of_wind_directions(Direction),
	%Ok so now map this list over (like previous function) the headings list to get list of head, side, tail and distances?

	{_Checksum, Polyline} = osrm:read_route(),
	Polyline_decoded = polyline:decode(Polyline),
	Distances_and_compass_list = convert_lats_longs_to_distance_heading(Polyline_decoded),
	%If now have a set of co-ords need to figure out distances and directions
	Distances_and_wind_type_list = lists:map(
		fun({Distance, Compass}) ->
			Wind_type = head_side_or_tail_wind(Compass, [Headwinds, Sidewinds, Tailwinds]),
			{Distance, Wind_type}
		end,
		Distances_and_compass_list),

	[Headwind_distances, Sidewind_distances, Tailwind_distances] = lists:map(
		fun(Wind_type_filter) ->
			lists:filter(
				fun({_Distance, Wind_type}) ->
					Wind_type == Wind_type_filter
				end,
				Distances_and_wind_type_list)
		end,
		[headwind, sidewind, tailwind]),



	[Sum_of_headwind_distances, Sum_of_sidewind_distances, Sum_of_tailwind_distances] = lists:map(
		fun(Wind_type) ->
			lists:foldl(
				fun({Distance, _Wind}, Sum) ->
					Distance + Sum
				end,
				0,
				Wind_type)
		end,
		[Headwind_distances, Sidewind_distances, Tailwind_distances]).
	%io:format("Direction: ~s~nSpeed: ~s mph~nGust: ~s mph~nWeather type: ~s~nTemperature: ~s deg C~n", [Direction, Speed, Gust, Weather_type, Temperature]).


%Need to read API key from file
readapikey() ->
	{_Status, Key} = file:read_file(os:getenv("HOME") ++ "/.datapoint"),
	string:strip(erlang:binary_to_list(Key),right,$\n).

Changes to osrm.erl.

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	URL = ?BASE_URL ++ ?VIAROUTE ++ "?loc=" ++ Start_lat ++ "," ++ Start_lon ++ "&loc=" ++ Finish_lat ++ "," ++ Finish_lon,
	%Need UA to work with OSRM API
	UA = "Mozilla/5.0 (X11; NetBSD i386; rv:28.0) Gecko/20100101 Firefox/28.0",
	try
		%Handling timeouts: http://stackoverflow.com/a/14143762/208793
		{ ok, {_Status, _Headers, Body }} = httpc:request(get, {URL, [{"User-Agent", UA}]}, [{timeout, timer:seconds(10)}], []),
		%For development purposes, write this out and keep it
		_WriteStatus = file:write_file(os:getenv("HOME") ++ "/.headsilose_route", Body),
		%Need to catch file write errors as well
		Body
	catch
		_:Reason ->
			io:format("API Might be down~n"),
			Reason
	after
................................................................................
	%And these don't seem to actually be returned, hence having to go down the route of polyline decoding
	%Route_Instructions = proplists:get_value(<<"route_instructions">>, Props),
	%Total_Distance = proplists:get_value(<<"total_distance">>, proplists:get_value(<<"route_summary">>, Props)),
	%And need to figure out how to get nested values. I.e like xpath. Just nest the queries? Nope that doesn't work
	%Like so:
	{Hint_data} = proplists:get_value(<<"hint_data">>, Props),
	Checksum = proplists:get_value(<<"checksum">>, Hint_data),
	Route_geometryS = binary:bin_to_list(Route_geometry),
	{Checksum, Route_geometryS}.


maybe_quit() ->
	Args = init:get_arguments(), 
	Found = lists:keyfind(noshell, 1, Args),
	if Found =:= false ->
		dont_quit;

	true -> init:stop()
	end.	







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	URL = ?BASE_URL ++ ?VIAROUTE ++ "?loc=" ++ Start_lat ++ "," ++ Start_lon ++ "&loc=" ++ Finish_lat ++ "," ++ Finish_lon,
	%Need UA to work with OSRM API
	UA = "Mozilla/5.0 (X11; NetBSD i386; rv:28.0) Gecko/20100101 Firefox/28.0",
	try
		%Handling timeouts: http://stackoverflow.com/a/14143762/208793
		{ ok, {_Status, _Headers, Body }} = httpc:request(get, {URL, [{"User-Agent", UA}]}, [{timeout, timer:seconds(10)}], []),
		%For development purposes, write this out and keep it
		_Write_status = file:write_file(os:getenv("HOME") ++ "/.headsilose_route", Body),
		%Need to catch file write errors as well
		Body
	catch
		_:Reason ->
			io:format("API Might be down~n"),
			Reason
	after
................................................................................
	%And these don't seem to actually be returned, hence having to go down the route of polyline decoding
	%Route_Instructions = proplists:get_value(<<"route_instructions">>, Props),
	%Total_Distance = proplists:get_value(<<"total_distance">>, proplists:get_value(<<"route_summary">>, Props)),
	%And need to figure out how to get nested values. I.e like xpath. Just nest the queries? Nope that doesn't work
	%Like so:
	{Hint_data} = proplists:get_value(<<"hint_data">>, Props),
	Checksum = proplists:get_value(<<"checksum">>, Hint_data),
	Route_geometry_as_string = binary:bin_to_list(Route_geometry),
	{Checksum, Route_geometry_as_string}.


maybe_quit() ->
	Args = init:get_arguments(),
	Found = lists:keyfind(noshell, 1, Args),
	if Found =:= false ->
		dont_quit;
	true ->
		init:stop()
	end.

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%See https://developers.google.com/maps/documentation/utilities/polylinealgorithm


decode(Encoded_polyline) ->
	%Steps 11 back to 8
	Six_bit_chunks = six_bit_chunks(Encoded_polyline),
	%Step 8
	List_of_groups_of_chunks = split_up_six_bits(Six_bit_chunks),
	%Step 8 back to 6
	Five_bit_chunks = five_bit_chunks(List_of_groups_of_chunks),
	%---TODO
	%Maybe some more of the below need splitting out into different functions or nesting in a map?
	%Which option to go for, a function that maps as per five_bit_chunks, or mapping functions as per below?
	%I don't think I can map all functions in one go because ultimately need to change number of members in groups.
	%I.e. following will go from groups of five to eight.
	%---
	%Step 5
................................................................................
			true ->
				Shifted_binary
			end,
			%Step 2 back to 1
			Decoded = if Last_bit =:= "1" ->
				-1 * Final_binary/100000;
			true ->
				Final_binary/100000	
			end,
			Decoded
		end,
		Eight_bit_chunks),
	Results.
	

%Step 8 - Split up six bit chunks, per the 0x20 bit
split_up_six_bits(List_of_bit_chunks) ->
	split_up_six_bits_(List_of_bit_chunks, [], []).
split_up_six_bits_([Head | Tail], Group_of_bit_chunks, List_of_groups_of_bit_chunks) when [hd(Head)] == "1" ->
	split_up_six_bits_(Tail, [Head]++Group_of_bit_chunks, List_of_groups_of_bit_chunks);
split_up_six_bits_([Head | Tail], Group_of_bit_chunks, List_of_groups_of_bit_chunks) when [hd(Head)] == "0" ->
	%Then need to start a new list, but after this 0 one!
	split_up_six_bits_(Tail, [], [lists:reverse([Head]++Group_of_bit_chunks)]++List_of_groups_of_bit_chunks);	
split_up_six_bits_([], Group_of_bit_chunks, List_of_groups_of_bit_chunks) when length(Group_of_bit_chunks) > 0 ->
	split_up_six_bits_([], [], [lists:reverse(Group_of_bit_chunks)]++List_of_groups_of_bit_chunks);
split_up_six_bits_([], [], List_of_groups_of_bit_chunks) ->
	%TODO Might be neater to map lists:reverse over the list instead of doing above and here.
	lists:reverse(List_of_groups_of_bit_chunks).


%Step 5
%TODO See if better way of doing this
eight_bit_chunks(List_of_five_bit_chunks) ->
	Five_bit_chunk_string = lists:reverse(lists:flatten(List_of_five_bit_chunks)),
	eight_bit_chunks_(Five_bit_chunk_string, []).
eight_bit_chunks_(Five_bit_chunk_string, List_of_eight_bit_chunks) when length(Five_bit_chunk_string) > 8 ->  
	Eight_bit_chunk = lists:reverse(lists:sublist(Five_bit_chunk_string,1,8)),
	Rest_of_five_bit_chunk_string = lists:nthtail(8,Five_bit_chunk_string),
	eight_bit_chunks_(Rest_of_five_bit_chunk_string, [Eight_bit_chunk]++List_of_eight_bit_chunks);
eight_bit_chunks_(Five_bit_chunk_string, List_of_eight_bit_chunks) when length(Five_bit_chunk_string) =< 8, Five_bit_chunk_string /= [] ->  
	Padded_bit_string = pad_to(8, lists:reverse(Five_bit_chunk_string)),
	eight_bit_chunks_([], [Padded_bit_string]++List_of_eight_bit_chunks);
eight_bit_chunks_([], List_of_eight_bit_chunks) ->
	List_of_eight_bit_chunks.


six_bit_chunks(Encoded_polyline) ->
	six_bit_chunks_(Encoded_polyline, []).
six_bit_chunks_([Head | Rest], List_of_chunks) ->
	Six_bit_chunk = six_bit_chunk(Head),
	%Add to Reversed_chunks
	six_bit_chunks_(Rest, [Six_bit_chunk]++List_of_chunks);
six_bit_chunks_([], List_of_chunks) ->
	lists:reverse(List_of_chunks).


six_bit_chunk(Ascii_bit) ->
	%Step 10
	Shifted_bit = Ascii_bit - 63,
	%Step 9
	%From http://erlangcentral.org/wiki/index.php/Converting_Between_Binary_and_Decimal
................................................................................
	%---TODO
	%What if Binary_chunk is shorter than 6?
	%Well in that case, I guess that means we'd want to split, but for now pad to six and check for 0x20 elsewhere.
	%---
	pad_to(6, Binary_chunk).


five_bit_chunks(List_of_groups_of_chunks) ->
	lists:map(
		fun(Group_of_chunks) ->
			%Step 7 - Un-reverse the five bit chunks
			lists:reverse(lists:map(
				fun(Chunk) ->
					%Step 8 - "Un-or" the 0x20 bit
					lists:sublist(Chunk,2,6)
				end,
				Group_of_chunks))
		end,
		List_of_groups_of_chunks).


%I can't figure out padding with io:format etc when printing binary numbers
pad_to(Length, Binary_string) when length(Binary_string) < Length ->
	Padded_binary_string = "0"++Binary_string,
	pad_to(Length, Padded_binary_string);
pad_to(Length, Binary_string) when length(Binary_string) == Length ->
	Binary_string.
	

%bnot doesn't seem to work as I thought it would so do it very inelegantly by switching each "bit" in a string.
bin_flip(Binary_number) ->
	Binary_string =	hd(io_lib:format("~.2B", [Binary_number])),
	bin_flip_(Binary_string, []).
bin_flip_([Head | Rest], Flipped_string) ->
	Head_bit = hd(io_lib:format("~c",[Head])),
	Flipped_bit = if Head_bit =:= "0" ->
		"1";
	true ->
		"0"







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%See https://developers.google.com/maps/documentation/utilities/polylinealgorithm


decode(Encoded_polyline) ->
	%Steps 11 back to 8
	Six_bit_chunks = six_bit_chunks(Encoded_polyline),
	%Step 8
	Groups_of_chunks_list = split_up_six_bits(Six_bit_chunks),
	%Step 8 back to 6
	Five_bit_chunks = five_bit_chunks(Groups_of_chunks_list),
	%---TODO
	%Maybe some more of the below need splitting out into different functions or nesting in a map?
	%Which option to go for, a function that maps as per five_bit_chunks, or mapping functions as per below?
	%I don't think I can map all functions in one go because ultimately need to change number of members in groups.
	%I.e. following will go from groups of five to eight.
	%---
	%Step 5
................................................................................
			true ->
				Shifted_binary
			end,
			%Step 2 back to 1
			Decoded = if Last_bit =:= "1" ->
				-1 * Final_binary/100000;
			true ->
				Final_binary/100000
			end,
			Decoded
		end,
		Eight_bit_chunks),
	Results.
	

%Step 8 - Split up six bit chunks, per the 0x20 bit
split_up_six_bits(Bit_chunks_list) ->
	split_up_six_bits_(Bit_chunks_list, [], []).
split_up_six_bits_([Head | Tail], Group_of_bit_chunks, Groups_of_bit_chunks_list) when [hd(Head)] == "1" ->
	split_up_six_bits_(Tail, [Head]++Group_of_bit_chunks, Groups_of_bit_chunks_list);
split_up_six_bits_([Head | Tail], Group_of_bit_chunks, Groups_of_bit_chunks_list) when [hd(Head)] == "0" ->
	%Then need to start a new list, but after this 0 one!
	split_up_six_bits_(Tail, [], [lists:reverse([Head]++Group_of_bit_chunks)]++Groups_of_bit_chunks_list);
split_up_six_bits_([], Group_of_bit_chunks, Groups_of_bit_chunks_list) when length(Group_of_bit_chunks) > 0 ->
	split_up_six_bits_([], [], [lists:reverse(Group_of_bit_chunks)]++Groups_of_bit_chunks_list);
split_up_six_bits_([], [], Groups_of_bit_chunks_list) ->
	%TODO Might be neater to map lists:reverse over the list instead of doing above and here.
	lists:reverse(Groups_of_bit_chunks_list).


%Step 5
%TODO See if better way of doing this
eight_bit_chunks(Five_bit_chunks_list) ->
	Five_bit_chunk_string = lists:reverse(lists:flatten(Five_bit_chunks_list)),
	eight_bit_chunks_(Five_bit_chunk_string, []).
eight_bit_chunks_(Five_bit_chunk_string, Eight_bit_chunks_list) when length(Five_bit_chunk_string) > 8 ->
	Eight_bit_chunk = lists:reverse(lists:sublist(Five_bit_chunk_string,1,8)),
	Rest_of_five_bit_chunk_string = lists:nthtail(8,Five_bit_chunk_string),
	eight_bit_chunks_(Rest_of_five_bit_chunk_string, [Eight_bit_chunk]++Eight_bit_chunks_list);
eight_bit_chunks_(Five_bit_chunk_string, Eight_bit_chunks_list) when length(Five_bit_chunk_string) =< 8, Five_bit_chunk_string /= [] ->
	Padded_bit_string = pad_to(8, lists:reverse(Five_bit_chunk_string)),
	eight_bit_chunks_([], [Padded_bit_string]++Eight_bit_chunks_list);
eight_bit_chunks_([], Eight_bit_chunks_list) ->
	Eight_bit_chunks_list.


six_bit_chunks(Encoded_polyline) ->
	six_bit_chunks_(Encoded_polyline, []).
six_bit_chunks_([Head | Rest], Chunks_list) ->
	Six_bit_chunk = six_bit_chunk(Head),
	%Add to Reversed_chunks
	six_bit_chunks_(Rest, [Six_bit_chunk]++Chunks_list);
six_bit_chunks_([], Chunks_list) ->
	lists:reverse(Chunks_list).


six_bit_chunk(Ascii_bit) ->
	%Step 10
	Shifted_bit = Ascii_bit - 63,
	%Step 9
	%From http://erlangcentral.org/wiki/index.php/Converting_Between_Binary_and_Decimal
................................................................................
	%---TODO
	%What if Binary_chunk is shorter than 6?
	%Well in that case, I guess that means we'd want to split, but for now pad to six and check for 0x20 elsewhere.
	%---
	pad_to(6, Binary_chunk).


five_bit_chunks(Groups_of_chunks_list) ->
	lists:map(
		fun(Group_of_chunks) ->
			%Step 7 - Un-reverse the five bit chunks
			lists:reverse(lists:map(
				fun(Chunk) ->
					%Step 8 - "Un-or" the 0x20 bit
					lists:sublist(Chunk,2,6)
				end,
				Group_of_chunks))
		end,
		Groups_of_chunks_list).


%I can't figure out padding with io:format etc when printing binary numbers
pad_to(Length, Binary_string) when length(Binary_string) < Length ->
	Padded_binary_string = "0"++Binary_string,
	pad_to(Length, Padded_binary_string);
pad_to(Length, Binary_string) when length(Binary_string) == Length ->
	Binary_string.


%bnot doesn't seem to work as I thought it would so do it very inelegantly by switching each "bit" in a string.
bin_flip(Binary_number) ->
	Binary_string = hd(io_lib:format("~.2B", [Binary_number])),
	bin_flip_(Binary_string, []).
bin_flip_([Head | Rest], Flipped_string) ->
	Head_bit = hd(io_lib:format("~c",[Head])),
	Flipped_bit = if Head_bit =:= "0" ->
		"1";
	true ->
		"0"