I am trying to split this statement in Lua
sendex,000D6F0011BA2D60,fb,btn,1,on,100,null
i need output like this way:
Mac:000D6F0011BA2D60
Value:1
command:on
value:100
how to split and get the values?
local input = "sendex,000D6F0011BA2D60,fb,btn,1,on,100,null"
local buffer = {}
for word in input:gmatch('[^,]+') do
table.insert(buffer, word)
--print(word) -- uncomment this to see the words as they are being matched ;)
end
print("Mac:"..buffer[2])
print("Value:"..buffer[5])
...
For a complete explanation of what string.gmatch does, see the Lua reference. To summarize, it iterates over a string and searches for a pattern, in this case [^,]+, meaning all groups of 1 or more characters that aren't a comma. Every time it finds said pattern, it does something with it and continues searching.
If your input is exactly like you have described, the code below works:
s="sendex,000D6F0011BA2D60,fb,btn,1,on,100,null"
Mac,Value,command,value = s:match(".-,(.-),.-,.-,(.-),(.-),(.-),")
print(Mac,Value,command,value)
It uses the non-greedy pattern .- to split the input into fields. It also captures the relevant fields.
Related
I can't figure out how to get Lua to return ALL matches for a particular pattern match.
I have the following regex which works and is so basic:
.*\n
This just splits a long string per line.
The equivelent of this in Lua is:
.-\n
If you run the above in a regex website against the following text it will find three matches (if using the global flag).
Hello
my name is
Someone
If you do not use the global flag it will return only the first match. This is the behaviour of LUA; it's as if it does not have a global switch and will only ever return the first match.
The exact code I have is:
local test = {string.match(string_variable_here, ".-\n")}
If I run it on the above test for example, test will be a table with only one item (the first row). I even tried using capture groups but the result is the same.
I cannot find a way to make it return all occurrences of a match, does anyone know if this is possible in LUA?
Thanks,
You can use string.gmatch(s, pattern) / s:gmatch(pattern):
This returns a pattern finding iterator. The iterator will search through the string passed looking for instances of the pattern you passed.
See the online Lua demo:
local a = "Hello\nmy name is\nSomeone\n"
for i in string.gmatch(a, ".*\n") do
print(i)
end
Note that .*\n regex is equivalent to .*\n Lua pattern. - in Lua patterns is the equivalent of *? non-greedy ("lazy") quantifier.
I have been trying to find all possible strings in between 2 strings
This is my input: "print/// to be able to put any amount of strings here endprint///"
The goal is to print every string in between print/// and endprint///
You can use Lua's string patterns to achieve that.
local text = "print/// to be able to put any amount of strings here endprint///"
print(text:match("print///(.*)endprint///"))
The pattern "print///(.*)endprint///" captures any character that is between "print///" and "endprint///"
Lua string patterns here
In this kind of problem, you don't use the greedy quantifiers * or +, instead, you use the lazy quantifier -. This is because * matches until the last occurrence of the sub-pattern after it, while - matches until the first occurence of the sub-pattern after it. So, you should use this pattern:
print///(.-)endprint///
And to match it in Lua, you do this:
local text = "print/// to be able to put any amount of strings here endprint///"
local match = text:match("print///(.-)endprint///")
-- `match` should now be the text in-between.
print(match) -- "to be able to put any amount of strings here "
I need to encapsulate in some way pattern in lua pattern matching to find whole sequence of this pattern in string. What do I mean by that.
For example we have string like that:
"word1,word2,word3,,word4,word5,word6, word7,"
I need to match first sequence of words followed by coma (word1,word2,word3,)
In python I would use this pattern "(\w+,)+", but similar pattern in lua (like (%w+,)+), will return just nil, because brackets in lua patterns means completely different thing.
I hope now you see my problem.
Is there a way to do repeating patterns in lua?
Your example wasn't too clear in terms of what should happen to the word4,word5,word6 and word7,
This would give you any seqence of comma separated words without white space or empty positions.
local text = "word1,word2,word3,,word4,word5,word6, word7,"
-- replace any comma followed by any white space or comma
--- by a comma and a single white space
text = text:gsub(",[%s,]+", ", ")
-- then match any sequence of >=1 non-whitespace characters
for sequence in text:gmatch("%S+,") do
print(sequence)
end
Prints
word1,word2,word3,
word4,word5,word6,
word7,
You could do this easily using LPeg if that's available to you:
local lpeg = require "lpeg"
local str = "word1,word2,word3,,word4,word5,word6, word7,"
local word = (lpeg.R"az"+lpeg.R"AZ"+lpeg.R"09") ^ 1
local sequence = lpeg.C((word * ",") ^1)
print(sequence:match(str))
I'm trying to match any strings that come in that follow the format Word 100.00% ~(45.56, 34.76) in LUA. As such, I'm looking to do a regex close (in theory) to this:
%D%s[%d%.%d]%%(%d.%d, %d.%d)
But I'm having no luck so far. LUA's patterns are weird.
What am I missing?
Your pattern is close you neglected to allow for multiple instances of a digit you can do this by using a + at like %d+.
You also did not use [,( and . correctly in the pattern.
[s in a pattern will create a set of chars that you are trying to match such as [abc] means you are looking to match any as bs or c at that position.
( are used to define a capture so the specific values you want returned rather then the whole string in the event of a match, in order to use it as a char you for the match you need to escape it with a %.
. will match any character rather then specifically a . you will need to add a % to escape if you want to match a . specifically.
local str = "Word 100.00% ~(45.56, 34.76)"
local pattern = "%w+%s%d+%.%d+%%%s~%(%d+%.%d+, %d+%.%d+%)"
print(string.match(str, pattern))
Here you will see the input string print if it matches the pattern otherwise you will see nil.
Suggested resource: Understanding Lua Patterns
I am relatively new to maxima. I want to know how to write an array into a text file using maxima.
I know it's late in the game for the original post, but I'll leave this here in case someone finds it in a search.
Let A be a Lisp array, Maxima array, matrix, list, or nested list. Then:
write_data (A, "some_file.data");
Let S be an ouput stream (created by openw or opena). Then:
write_data (A, S);
Entering ?? numericalio at the input prompt, or ?? write_ or ?? read_, will show some info about this function and related ones.
I've never used maxima (or even heard of it), but a little Google searching out of curiousity turned up this: http://arachnoid.com/maxima/files_functions.html
From what I can gather, you should be able to do something like this:
stringout("my_new_file.txt",values);
It says the second parameter to the stringout function can be one or more of these:
input: all user entries since the beginning of the session.
values: all user variable and array assignments.
functions: all user-defined functions (including functions defined within any loaded packages).
all: all of the above. Such a list is normally useful only for editing and extraction of useful sections.
So by passing values it should save your array assignments to file.
A bit more necroposting, as google leads here, but I haven't found it useful enough. I've needed to export it as following:
-0.8000,-0.8000,-0.2422,-0.242
-0.7942,-0.7942,-0.2387,-0.239
-0.7776,-0.7776,-0.2285,-0.228
-0.7514,-0.7514,-0.2124,-0.212
-0.7168,-0.7168,-0.1912,-0.191
-0.6750,-0.6750,-0.1655,-0.166
-0.6272,-0.6272,-0.1362,-0.136
-0.5746,-0.5746,-0.1039,-0.104
So I've found how to do this with printf:
with_stdout(filename, for i:1 thru length(z_points) do
printf (true,"~,4f,~,4f,~,4f,~,3f~%",bot_points[i],bot_points[i],top_points[i],top_points[i]));
A bit cleaner variation on the #ProdoElmit's answer:
list : [1,2,3,4,5]$
with_stdout("file.txt", apply(print, list))$
/* 1 2 3 4 5 is then what appears in file.txt */
Here the trick with apply is needed as you probably don't want to have square brackets in your output, as is produced by print(list).
For a matrix to be printed out, I would have done the following:
m : matrix([1,2],[3,4])$
with_stdout("file.txt", for row in args(m) do apply(print, row))$
/* 1 2
3 4
is what you then have in file.txt */
Note that in my solution the values are separated with spaces and the format of your values is fixed to that provided by print. Another caveat is that there is a limit on the number of function parameters: for example, for me (GCL 2.6.12) my method does not work if length(list) > 64.