Sorting key value pairs results ?

parkerc · November 12, 2017, 2:29pm

Hi

Calling all the lua experts out there,

When someone has time - please could they help update the following code so that the printed list is sorted in order of the oldest one first (longest period since Sensor was last updated)

[code]-- Basis taken from Door/Window sensor check and speech annotation by Pasqual Zottola

local devcnt = 0
local devno = 0
local numopen = 0
local isare = “is”
local opensensors = " "
local SSID = “urn:micasaverde-com:serviceId:SecuritySensor1”

for deviceNo,d in pairs(luup.devices) do
if d.category_num == 4 then

  local tripped = luup.variable_get(SSID, "Tripped", deviceNo) or "Nil"
  local lastTrip = luup.variable_get (SSID, "LastTrip", deviceNo) or os.time()

local timeString = os.date(" %Y/%m/%d - %X", lastTrip)

  lastTrip = tonumber (lastTrip)
  
  if (tripped == "1") then
     opensensors = opensensors .. ". " .. d.description
    
     numopen = numopen + 1
  end

print (
lastTrip …
’ a.k.a ’ … timeString …
’ : ’ … d.description … " Sensor was last tripped")

devcnt = devcnt + 1
end
end

if numopen == 0 then --If there are no sensors tripped, log and announce!
print ("- - - - ")
print(‘There were ’ … devcnt … ’ door and window sensors found and all are closed’)

else --If there are any sensors tripped, log and announce!

if numopen > 1 then
isare = “are”
end
print ("- - - - ")
print (‘There were ’ … devcnt … ’ door and window sensors found and ’ … numopen … " " … isare … ’ currently open’ … opensensors)
end[/code]

akbooer · November 12, 2017, 2:53pm

You’re going to have to do some of the work yourself, but the basic idea is to put the results into an array, and then sort the array. Alternatively, make a list of the array indices (ie. device numbers) and sort those by update time, then use the sorted list to index your main loop.

parkerc · November 12, 2017, 10:32pm

I had tried but the things I read made limited sense, and I really just wanted the answer - hence the post …

I did look at adding the creation of an array to the code,

listing {}

And I also read these about sorting/tables (below) , but due to my ew job I have such limited time, I hoped it was a quick one for someone.

https://www.lua.org/pil/19.3.html

If no one has the answer, then a Vera/luup example might help.

Either way - thanks .

rigpapa · November 13, 2017, 2:36am

This code will sift through luup.devices taking all devices that have LastTrip set, then sort them most to least recent, then print (log) the list. I hope you find this helpful.

[tt]local d, n
local tt = {}
for n,d in pairs(luup.devices) do
local lasttrip = tonumber(luup.variable_get(“urn:micasaverde-com:serviceId:SecuritySensor1”, “LastTrip”, n) or 0,10)
if lasttrip > 0 then
table.insert(tt, { devnum=n, last=lasttrip })
end
end
table.sort(tt, function(a,b) return a.last > b.last end) – sort highest to lowest
for n,d in ipairs(tt) do
luup.log(d.devnum … " name " … luup.devices[d.devnum].description … " last trip " … d.last)
end[/tt]

To do oldest first, just change the > in the sort function to a <.

parkerc · November 13, 2017, 9:54am

Huge Thanks @rigpapa

Im embarrassed to say it but I really struggled trying to work out how to do this. It not helped I think by the fact that Im still getting to grips with arrays and tables. I had tried reworking this taken from a Lua Tutorial into my code above but it did not seem to do anything,

a = {} i n in pairs(listing) do table.insert(a, n) end table.sort(a) for i,n in ipairs(a) do print(n) end

I had also read this - lua-users wiki: For Tutorial (Numeric progression) but so much felt like gobbledygook

Im beginning to come to resign myself to the fact that my programming skills are more akin to a musician that learns best by their ear, rather than by reading music. :).

Show me a working example and I can have a good go at reverse engineering it for how I might need it.

Many thanks again.

@akbooer thanks for responding too, I know you are only trying to help (… teach a man to fish etc… )

rigpapa · November 13, 2017, 2:20pm

Keep at it. Working from examples and templates is a time-tested way to bootstrap yourself. I’ve been programming since punched cards and paper tape days, but there’s always something new and I still enjoy the “ah-hah” moments the most.

parkerc · November 15, 2017, 9:27am

Thanks again @rigpapa

Having that example allowed me to see better how the pairs and ipairs work in practice with Vera. I had seen example on the LUA site but they just didn?t sink in. (One creates the table and the other updates it?)

For others reading this …

Here?s my updated code, which sorts in order (by human readable time) when all your security Sensors were last tripped.

[code]local d, n
local tt = {}
for n,d in pairs(luup.devices) do

if d.category_num == 4 then
local lasttrip = tonumber(luup.variable_get ("urn:micasaverde-com:serviceId:SecuritySensor1", "LastTrip", n) or os.time())
local timeString = os.date(" %Y/%m/%d - %X", lasttrip)

if lasttrip > 0 then
    table.insert(tt, { devnum=n, last=lasttrip, ltime=timeString })
end

end
end

table.sort(tt, function(a,b) return a.last > b.last end) – sort highest to lowest

for n,d in ipairs(tt) do
print (
d.ltime …
’ : ’ … luup.devices[d.devnum].description … " Sensor was last tripped")
end[/code]

Resulting print out, with most recent at the top…

2017/11/15 - 09:14:33 : 07. Bedroom Sensor was last tripped 2017/11/15 - 09:09:43 : 20. Living Room Sensor was last tripped 2017/11/15 - 09:09:34 : 18. Hallway Sensor was last tripped 2017/11/15 - 09:08:48 : 13. Conservatory Sensor was last tripped 2017/11/15 - 09:08:43 : 12. Dining Room Sensor was last tripped 2017/11/15 - 09:08:01 : 10. Kitchen Sensor was last tripped

Some questions.

I wanted to ask you about a line you used below (I changed it) as I was not sure what it exactly did ? Can you help me understand.

Yours - local lasttrip = tonumber(luup.variable_get(“urn:micasaverde-com:serviceId:SecuritySensor1”, “LastTrip”, n) or 0,10)

I changed it to - local lasttrip = tonumber(luup.variable_get (“urn:micasaverde-com:serviceId:SecuritySensor1”, “LastTrip”, n) or os.time())

Also why do we define local values d, n first ?
Do we have to when they are going to be defined/used as the key and value for the pairs (array/table creation)?
I can exclude them and it still works?
Is a table and array the same thing ?

rigpapa · November 16, 2017, 7:06pm

Yours - local lasttrip = tonumber(luup.variable_get("urn:micasaverde-com:serviceId:SecuritySensor1", "LastTrip", n) or 0,10)
I changed it to - local lasttrip = tonumber(luup.variable_get (“urn:micasaverde-com:serviceId:SecuritySensor1”, “LastTrip”, n) or os.time())

That seems fine. Any default that works for your intended semantics is A-OK.

2) Also why do we define local values d, n first ?

I declared d and n first so they are not created as globals. If you set d to a value before declaring it as a local variable, Lua will make it global. I’m not a fan of globals, although they do have their place, and Luup forces us to use them, but I try to avoid creating them myself unless there’s a clear benefit/need. Probably my #1 wish for Lua is that it had a “strict” mode that would just trap when a variable is set or used before being declared (fortunately there are ways to do this, just not built-in).

3) Is a table and array the same thing ?

An array is a table, where the keys are unbroken/sequential numeric values starting at one. They are not different structures or types in Lua, though. This causes some interesting behaviors with pairs() and ipairs(). Consider the following initialization of a table:

[tt]local t = {}
t[1] = “A”
t[0] = “zero”
t[99] = “last”[/tt]

Note that we have non-sequential indexes (or indices if you prefer), and 0 (recall Lua arrays start at 1). If you iterate over t using pairs(), you will get this:

[tt]local k,v
for k,v in pairs(t) do
print(k … “=” … v)
end

1=A
0=zero
99=last[/tt]

I think that’s pretty much what you’d expect. However, if you use ipairs() instead, Lua produces the following output:

[tt]for k,v in ipairs(t) do print(k … “=” … v) end

1=A[/tt]

The table elements with keys 0 and 99 (numeric) aren’t returned in the ipairs() iteration. This is because ipairs() really assumes its table argument is being used strictly as an array, so it only iterates from 1 up and stops when an index is missing. It doesn’t print 0 because Lua arrays start at 1, and it doesn’t print 99 because 2, 3, and everything else in between are missing (non-sequential).

Generally, unless you are very sure the table you are dealing with is an array, it’s safer to use pairs() instead of ipairs(). And when dealing with a true, bona-fide array, if using the [tt]table[numericIndex]=value[/tt] form to add array elements you should take extra care to make sure your index values are sequential or (preferably, IMO) use [tt]table.insert()[/tt] for adding elements; and if removing a value from an array, do not use the [tt]table[index]=nil[/tt] form (which creates a gap), but rather [tt]table.remove()[/tt].

parkerc · November 17, 2017, 8:57am

Massive thanks @rigpapa that helps a lot…

Ive updated our code with some HTML so that the table published via sb.html has borders.

[code]local d, n
local file = io.open(“/www/sb.html”, “w”)
file:write(“.custom { font-size: 1em; font-family: Gill Sans Extrabold, sans-serif; padding:5px; border-collapse: collapse; border: 1px solid black; }\n”)

local tt = {}
for n,d in pairs(luup.devices) do

if d.category_num == 4 then
local lasttrip = tonumber(luup.variable_get ("urn:micasaverde-com:serviceId:SecuritySensor1", "LastTrip", n) or os.time())
local timeString = os.date(" %Y/%m/%d - %X", lasttrip)

if lasttrip > 0 then
    table.insert(tt, { devnum=n, last=lasttrip, ltime=timeString })
end

end
end

table.sort(tt, function(a,b) return a.last > b.last end) – sort highest to lowest

for n,d in ipairs(tt) do

file:write(“

\n”)

print (
d.ltime ..

’ : ’ … luup.devices[d.devnum].description … " Sensor was last tripped")
end
file:write(“

Security Sensor	Last Tripped
” … luup.devices[d.devnum].description … “	”… d.ltime … “

\n”)
file:close()[/code]

Looking at our script - if I understand everything correctly luup.devices is already an indexed table - http://wiki.micasaverde.com/index.php/Luup_Lua_extensions#variable:_devices

How do I see (print out) that entire table to see all the contents ?

In your example we defined the table as t, but how can you indentify a predefined table or an array E.g luup.devices, luup.rooms, luup.scenes etc?

rigpapa · November 17, 2017, 7:13pm

For the luup tables (devices, scenes, etc.) you should use [tt]pairs()[/tt], as these tables are not arrays. The key values are the IDs of their respective objects, and so the table may (will at some point) have gaps in sequencing that make [tt]ipairs()[/tt] an incorrect choice for iteration.

Here is code I often use to dump the contents of tables…

[tt]local function dump(t)
if t == nil then return “nil” end
if type(t) ~= “table” then return tostring(t) end
local k,v,str,val
local sep = “”
local str = “{ "
for k,v in pairs(t) do
if type(v) == “table” then
val = dump(v)
elseif type(v) == “function” then
val = “(function)”
elseif type(v) == “string” then
val = string.format(”%q", v)
else
val = tostring(v)
end
str = str … sep … k … “=” … val
sep = “, "
end
str = str … " }”
return str
end
local k,v
for k,v in pairs(luup.devices) do
luup.log(“device #” … k … “=” … dump(v))
end
[/tt]

RichardTSchaefer · November 17, 2017, 8:38pm

You should also put a decent depth in your dump function.
There are many LUA objects that are recursive.
You can also use the depth to indent the content to better see the structure.