I'm building a internet connected BitCoin app. To watch the ticker info from different bitcoin markets.
Everything works. Now I want to send a list of available markets down to the watch to be displayed as a menu.
JSON to be sent:
{"markets": ["MtGox", "BitStamp","BTCChina"]}
"markets" is properly keyed in "appinfo.json" so this is not a problem.
How do I access an element (single string) in this array on the Pebble? I've seen examples of accessing ints and strings directly and these work great, are there any good examples of this? I have not found any.
I am assuming you are using the PebbleKit JS API. The appropriate doc is at: https://developer.getpebble.com/2/guides/javascript-guide.html
The doc says you can only send dictionaries with values as ints, strings, or byte arrays.
To send a list of strings, you have different options.
Send several key/value pairs, starting at a known index
{ 100: "MtGox", 101: "BitStamp", 102: "BTCChina" }
Send one string with a known separator and split it on the watch
{ "markets": "MtGox|BitStamp|BTCChina" }
Send an array of bytes with a list of keys that contain a market name
{ "markets": [100, 101, 102],
100: "MtGox", 101: "BitStamp", 102: "BTCChina"
}
Related
I am investigating migrating of a highly customized and efficient binary format to one of the available binary formats. The data is stored on some low powered mobile among other places, so performance is important requirement.
Advantage of the current format is that all strings are stored in a pool. This means that we don't repeat the same string hundred of times in file, we read it only once during deserialization and all objects are referencing it by its index. It also means that we keep only one copy in memory. So a lot of advantages :)
I was not able to find a way for capnproto or flatbuffers to support this. Or would I need to build layer on top, and in generated object use integer index to strings explicitly?
Thanks you!
FlatBuffers supports string pooling. Simply serialize a string once, then refer to that string multiple times in other objects. The string will only occur in memory once.
Simplest example, schema:
table MyObject { name: string; id: string; }
code (C++):
FlatBufferBuilder fbb;
auto s = fbb.CreateString("MyPooledString");
// Both string fields point to the same data:
auto o = CreateMyObject(fbb, s, s);
fbb.Finish(o);
You can always do this manually like:
struct MyMessage {
stringTable #0 :List(Text);
# Now encode string fields as integer indexes into the string table.
someString #1 :UInt32;
otherString #2 :UInt32;
}
Cap'n Proto could in theory allow multiple pointers to point at the same object, but currently prohibits this for security reasons: it would be too easy to DoS servers that don't expect it by sending messages that are cyclic or contain lots of overlapping references. See the section on amplification attacks in the docs.
Been looking all over the place for a solution to this issue. I have a Yahoo Pipe (http://pipes.yahoo.com/pipes/pipe.info?_id=e5420863cfa494ee40e4c9be43f0e812) that I've created to pull back image content from the Bing Search API. The URL builder includes a $skip attribute that takes an integer and uses it to select the starting (index) point for the result set that the query returns.
My initial plan had been to use the math engine in the Wolfram Alpha API to generate a random number (randomInteger[1000]) that I could use to seed the $skip value each time that the pipe is run. I have an earlier version of the pipe where I was able to get the query / result steps working using either "XPath Fetch" and "Fetch Data". However, regardless of how I Fetch the result, the response returns as an attribute / value pair in a list item.Even when I use "Emit items as string" in XPath Fetch, I still get a list with a single item, when what I really want is the integer that I can plug into my $skip attribute.
I've tried everything in Pipes I can think of, and spent a lot of time online looking for an answer. Is there anyway to extract text (in this case, a number) from a single list item and then use the output as input to "wire" a text parameter in another Pipes block? Any suggestions / ideas welcome. In the meantime, I'm generating a sorta-random number by manipulating a timecode hash, but it just feels tacky :-)
Thanks!
All the sources are for repeated items. You can't have a source that just makes a single number.
I'm not really clear what you're trying to do. You want to put a random number into part of the URL string that gets an RSS feed?
I'm downloading content from a webpage that seems to be in JSON. It is a large file with the following format:
"address1":"123 Street","address2":"Apt 1","city":"City","state":"ST","zip":"xxxxx","country":"US"
There are about 1000 of these entries, where each entry is contained within brackets. When I download the page using RestClient.get (open-uri for some reason was throwing a http 500 error), the data is in the following format:
\"address\1":\"123 Street\",\"address2\":\"Apt 1\",\"city\":\"City\",\"state\":\"ST\",\"zip\":\"xxxxx\",\"country\":\"US\"
When I then use the json class
parsed = JSON.parse(data_out)
it completely scrambles both the order of entries within the data structure, and also the order of the objects within each entry, for example:
"address1"=>"123 Street", "city"=>"City", "country"=>"US", "address2"=>"Apt 1"
If instead I use
data_j=data_out.to_json
then I get:
\\\"address\\\1":\\\"123 Street\\\",\\\"address2\\\":\\\"Apt 1\\\",\\\"city\\\":\\\"City\\\",\\\"state\\\":\\\"ST\\\",\\\"zip\\\":\\\"xxxxx\\\",\\\"country\\\":\\\"US\\\"
Further, only using the json class seems to allow me to select the entries I want:
parsed[1]["address1"]
=> "123 Street"
data_j[1]["address1"]
TypeError: can't convert String into Integer
from (irb):17:in `[]'
from (irb):17
from :0
Any idea whats going on? I guess since the json commands are working I can use them, but it is disconcerting that its scrambling the entries and order of the objects.
Although the data appears ordered in string form, it represents an unordered dataset. The line:
parsed = JSON.parse(data_out)
which you use is the correct way to convert the string form into something usable in Ruby. I cannot see the full structure from your example, so I don't know whether the top level is an array or id-based hash. I suspect the latter since you say it becomes unordered when you view from Ruby. Therefore, if you knew which part of the address you were interested in you might have code like this:
# Writes all the cities
parsed.each do |id,data|
puts data["city"]
end
If the outer structure is an array, you'd do this:
# Writes all the cities
parsed.each do |data|
puts data["city"]
end
I have a list of objects that are returned as a sequence, I would like to retrieve the keys of each object so as to be able to display the object correctly. At the moment I try data?first?keys which seems to get something like the queries that return the objects (Not sure how to explain that last sentence either but img below shows what I'm trying to explain).
The objects amount of objects returned are correct (7) but displaying the keys for each object is my aim. The macro that attempts this is here (from the apache ofbiz development book chapter 8).
Seems like it my sequence is a list of hashes and as explained by Daniel Dekany this post:
The original problem is that, someHash[key] expects a
string as key. Because, the hash type of FTL, by definition, maps
string keys to arbitrary values. It's not the same as Java's Map.
(Note that to further complicate the matters, in FTL
someSequenceOrString[index] expects an integer index. So, the [] thing
is used for that too.) Now someBeanWrappedMap(key) has technically
nothing to do with all the []-s, it's just a method call, so it
accepts all kind of keys. If you have a Map with non-string keys, you
must use that.
Thanks D Dekany if you're on stack, this ended my half day frustration with the ftl template.
I've been playing around with a .lua file which passes a random phrase using the following line:
SendChatMessage(GetRandomArgument("text1", "text2", "text3", "text4"), "RAID")
My problem is that I have a lot of phrases and the one line of code is very long indeed.
Is there a way to hold
text1
text2
text3
text3
in a list somewhere else in the code (or externally) and call a random value from the main code. Would make maintaining the list of text options easier.
For lists up to a few hundred elements, then the following will work:
messages = {
"text1",
"text2",
"text3",
"text4",
-- ...
}
SendChatMessage(GetRandomArgument(unpack(messages)), "RAID")
For longer lists, you would be well served to replace GetRandomArgument with GetRandomElement that would take a single table as its argument and return a random entry from the table.
Edit: Olle's answer shows one way that something like GetRandomElement might be implemented. But it used table.getn on every call which is deprecated in Lua 5.1, and its replacement (table.maxn) has a runtime cost proportional to the number of elements in the table.
The function table.maxn is only required if the table in use might have missing elements in its array part. However, in this case of a list of items to choose among, there is likely to be no reason to need to allow holes in the list. If you need to edit the list at run time, you can always use table.remove to remove an item since it will also close the gap.
With a guarantee of no gaps in the array of text, then you can implement GetRandomElement like this:
function GetRandomElement(a)
return a[math.random(#a)]
end
So that you send the message like this:
SendChatMessage(GetRandomElement(messages), "RAID")
You want a table to contain your phrases like
phrases = { "tex1", "text2", "text3" }
table.insert(phrases ,"text4") -- alternative syntax
SendChatMessage(phrases[math.random(table.getn(phrases))], "RAID")
Note: getn gets the size of the table; math.random gets a random number (with a max of the size of the phrases table) and the phrases[] syntax returns the table element at the index inside [].