Is there an easy way to split a string like this:
M34a79 or M2ab943 or M4c4
into
M,34,a,79 or M,2,ab,943 or M,4,c,4
without any separators?
You can do it with a pair of gsub calls:
x = "M34a79 or M2ab943 or M4c4"
x, _ = x:gsub( "(%d)(%a)", "%1,%2" )
x, _ = x:gsub( "(%a)(%d)", "%1,%2" )
print( x )
M,34,a,79 or M,2,ab,943 or M,4,c,4
Might not work in all cases, but does work on your example.
If you don’t mind using the LPEG
library:
local lpeg = require "lpeg"
local C, Ct, P, R = lpeg.C, lpeg.Ct, lpeg.P, lpeg.R
local lpegmatch = lpeg.match
local extract
do
local digit = R"09"
local lower = R"az"
local comma = P","
local space = P" "
local schema = Ct( C(P"M")
* (digit^1 / tonumber)
* C(lower^1)
* (digit^1 / tonumber))
local extractor = Ct((schema + 1)^0)
extract = function (str)
return lpegmatch (extractor, str)
end
end
This will match all sequences of characters of the input
that consist of (in that order)
the letter M,
a sequence of 1 or more decimal digits,
a sequence of 1 or more lowercase characters, and
another sequence of 1 or more decimal digits.
When processing the input each match is put in a subtable,
the digits are converted to Lua numbers on the fly.
Since the question requested it, the leading M is included
in the entries.
Usage example:
local data = extract [[M34a79 or M2ab943 or M4c4]]
for i = 1, #data do
local elm = data[i]
print (string.format ("[%d] = { [1] = %q, [2] = %d, [3] = %q, [4] = %d },",
i, table.unpack (elm)))
end
Output:
[1] = { [1] = "M", [2] = 34, [3] = "a", [4] = 79 },
[2] = { [1] = "M", [2] = 2, [3] = "ab", [4] = 943 },
[3] = { [1] = "M", [2] = 4, [3] = "c", [4] = 4 },
Solution:
http://www.coronalabs.com/blog/2013/04/16/lua-string-magic/
function string:split( inSplitPattern, outResults )
...
end
function val(x)
x = x:gsub( "(%d)(%a)", "%1,%2" )
x = x:gsub( "(%a)(%d)", "%1,%2" )
Table = string.split(x,",")
for i = 1, #Table do
print( Table[i] )
end
end
val("M3a5")
returns M 3 a 5
Related
I have a string that contains different ranges and I need to find their value
var str = "some text x = 1..14, y = 2..4 some text"
I used the substringBefore() and substringAfter() methodes to get the x and y but I can't find a way to get the values because the numbers could be one or two digits or even negative numbers.
One approach is to use a regex, e.g.:
val str = "some text x = 1..14, y = 2..4 some text"
val match = Regex("x = (-?\\d+[.][.]-?\\d+).* y = (-?\\d+[.][.]-?\\d+)")
.find(str)
if (match != null)
println("x=${match.groupValues[1]}, y=${match.groupValues[2]}")
// prints: x=1..14, y=2..4
\\d matches a single digit, so \\d+ matches one or more digits; -? matches an optional minus sign; [.] matches a dot; and (…) marks a group that you can then retrieve from the groupValues property. (groupValues[0] is the whole match, so the individual values start from index 1.)
You could easily add extra parens to pull out each number separately, instead of whole ranges.
(You may or may not find this as readable or maintainable as string-manipulation approaches…)
Is this solution fit for you?
val str = "some text x = 1..14, y = 2..4 some text"
val result = str.replace(",", "").split(" ")
var x = ""; var y = ""
for (i in 0..result.count()-1) {
if (result[i] == "x") {
x = result[i+2]
} else if (result[i] == "y") {
y = result[i+2]
}
}
println(x)
println(y)
Using KotlinSpirit library
val rangeParser = object : Grammar<IntRange>() {
private var first: Int = -1
private var last: Int = -1
override val result: IntRange
get() = first..last
override fun defineRule(): Rule<*> {
return int {
first = it
} + ".." + int {
last = it
}
}
}.toRule().compile()
val str = "some text x = 1..14, y = 2..4 some text"
val ranges = rangeParser.findAll(str)
https://github.com/tiksem/KotlinSpirit
I'm trying to encode some strings in my lua script, and since that I have a lua script with over 200k characters, encrypting each string query in the script with a function such as this example below
local string = "stackoverflow"
local string = [[stackoverflow]]
local string = [==[stackoverflow]==]
local string = 'stackoverflow'
to
local string=decode("jkrtbfmviwcfn",519211)
Trying to provide all above results to thread through a gsub and have the gsub encode the string text with a random offset number.
So far, I was only capable of gsubbing full quotation marks through.
function encode(x,offset,a)
for char in string.gmatch(x, "%a") do
local encrypted = string.byte(char) + offset
while encrypted > 122 do
encrypted = encrypted - 26
end
while encrypted < 97 do
encrypted = encrypted + 26
end
a[#a+1] = string.char(encrypted)
end
return table.concat(a)
end
luacode=[==[thatstring.Value="Encryptme!" testvalue.Value=[[string with
a linebreak]] string.Text="STOP!"]==]
luacode=luacode:gsub([=["(.-)"]=],function(s)
print("Caught "..s)
local offset=math.random(1,4)
local encoded=encode(s,offset,{})
return [[decode("]]..encoded..[[",]]..offset..[[)]]
end)
print("\n"..luacode)
With its output being
Caught Encryptme!
Caught STOP!
thatstring.Value=decode("crgvctxqi",4) testvalue.Value=[[string with
a linebreak]] string.Text=decode("opkl",2)
Any better solutions?
local function strings_and_comments(lua_code, callback)
-- lua_code must be valid Lua code (an error may be raised on syntax error)
-- callback will be invoked as callback(object_type, value, start_pos, end_pos)
-- callback("comment", comment_text, start_pos, end_pos) -- for comments
-- callback("string", string_value, start_pos, end_pos) -- for string literals
local objects = {} -- possible comments and string literals in the code
-- search for all start positions of comments (with false positives)
for pos, br1, eq, br2 in lua_code:gmatch"()%-%-(%-*%[?)(=*)(%[?)" do
table.insert(objects, {start_pos = pos,
terminator = br1 == "[" and br2 == "[" and "]"..eq.."]" or "\n"})
end
-- search for all start positions of string literals (with false positives)
for pos, eq in lua_code:gmatch"()%[(=*)%[[%[=]*" do
table.insert(objects, {is_string = true, start_pos = pos,
terminator = "]"..eq.."]"})
end
for pos, quote in lua_code:gmatch"()(['\"])" do
table.insert(objects, {is_string = true, start_pos = pos, quote = quote})
end
table.sort(objects, function(a, b) return a.start_pos < b.start_pos end)
local end_pos = 0
for _, object in ipairs(objects) do
local start_pos, ok, symbol = object.start_pos
if start_pos > end_pos then
if object.terminator == "\n" then
end_pos = lua_code:find("\n", start_pos + 1, true) or #lua_code
-- exclude last spaces and newline
while lua_code:sub(end_pos, end_pos):match"%s" do
end_pos = end_pos - 1
end
elseif object.terminator then
ok, end_pos = lua_code:find(object.terminator, start_pos + 1, true)
assert(ok, "Not a valid Lua code")
else
end_pos = start_pos
repeat
ok, end_pos, symbol = lua_code:find("(\\?.)", end_pos + 1)
assert(ok, "Not a valid Lua code")
until symbol == object.quote
end
local value = lua_code:sub(start_pos, end_pos):gsub("^%-*%s*", "")
if object.terminator ~= "\n" then
value = assert((loadstring or load)("return "..value))()
end
callback(object.is_string and "string" or "comment", value, start_pos, end_pos)
end
end
end
local inv256
local function encode(str)
local seed = math.random(0x7FFFFFFF)
local result = '",'..seed..'))'
if not inv256 then
inv256 = {}
for M = 0, 127 do
local inv = -1
repeat inv = inv + 2
until inv * (2*M + 1) % 256 == 1
inv256[M] = inv
end
end
repeat
seed = seed * 3
until seed > 2^43
local K = 8186484168865098 + seed
result = '(decode("'..str:gsub('.',
function(m)
local L = K % 274877906944 -- 2^38
local H = (K - L) / 274877906944
local M = H % 128
m = m:byte()
local c = (m * inv256[M] - (H - M) / 128) % 256
K = L * 21271 + H + c + m
return ('%02x'):format(c)
end
)..result
return result
end
function hide_strings_in_lua_code(lua_code)
local text = { [[
local function decode(str, seed)
repeat
seed = seed * 3
until seed > 2^43
local K = 8186484168865098 + seed
return (str:gsub('%x%x',
function(c)
local L = K % 274877906944 -- 2^38
local H = (K - L) / 274877906944
local M = H % 128
c = tonumber(c, 16)
local m = (c + (H - M) / 128) * (2*M + 1) % 256
K = L * 21271 + H + c + m
return string.char(m)
end
))
end
]] }
local pos = 1
strings_and_comments(lua_code,
function (object_type, value, start_pos, end_pos)
if object_type == "string" then
table.insert(text, lua_code:sub(pos, start_pos - 1))
table.insert(text, encode(value))
pos = end_pos + 1
end
end)
table.insert(text, lua_code:sub(pos))
return table.concat(text)
end
Usage:
math.randomseed(os.time())
-- This is the program to be converted
local luacode = [===[
print"Hello world!"
print[[string with
a linebreak]]
local str1 = "stackoverflow"
local str2 = [[stackoverflow]]
local str3 = [==[stackoverflow]==]
local str4 = 'stackoverflow'
print(str1)
print(str2)
print(str3)
print(str4)
]===]
-- Conversion
print(hide_strings_in_lua_code(luacode))
Output (converted program)
local function decode(str, seed)
repeat
seed = seed * 3
until seed > 2^43
local K = 8186484168865098 + seed
return (str:gsub('%x%x',
function(c)
local L = K % 274877906944 -- 2^38
local H = (K - L) / 274877906944
local M = H % 128
c = tonumber(c, 16)
local m = (c + (H - M) / 128) * (2*M + 1) % 256
K = L * 21271 + H + c + m
return string.char(m)
end
))
end
print(decode("ef869b23b69b7fbc7f89bbe7",2686976))
print(decode("c2dc20f7061c452db49302f8a1d9317aad1009711e0984",1210253312))
local str1 = (decode("84854df4599affe9c894060431",415105024))
local str2 = (decode("a5d7db792f0b514417827f34e3",1736704000))
local str3 = (decode("6a61bcf9fd6f403ed1b4846e58",1256259584))
local str4 = (decode("cad56d9dea239514aca9c8b8e0",1030488064))
print(str1)
print(str2)
print(str3)
print(str4)
Output of output (output produced by the converted program)
Hello world!
string with
a linebreak
stackoverflow
stackoverflow
stackoverflow
stackoverflow
I want to have ability to use a lastIndexOf method for the strings in my Lua (Luvit) project. Unfortunately there's no such method built-in and I'm bit stuck now.
In Javascript it looks like:
'my.string.here.'.lastIndexOf('.') // returns 14
function findLast(haystack, needle)
local i=haystack:match(".*"..needle.."()")
if i==nil then return nil else return i-1 end
end
s='my.string.here.'
print(findLast(s,"%."))
print(findLast(s,"e"))
Note that to find . you need to escape it.
If you have performance concerns, then this might be a bit faster if you're using Luvit which uses LuaJIT.
local find = string.find
local function lastIndexOf(haystack, needle)
local i, j
local k = 0
repeat
i = j
j, k = find(haystack, needle, k + 1, true)
until j == nil
return i
end
local s = 'my.string.here.'
print(lastIndexOf(s, '.')) -- This will be 15.
Keep in mind that Lua strings begin at 1 instead of 0 as in JavaScript.
Here’s a solution using
LPeg’s position capture.
local lpeg = require "lpeg"
local Cp, P = lpeg.Cp, lpeg.P
local lpegmatch = lpeg.match
local cache = { }
local find_last = function (str, substr)
if not (str and substr)
or str == "" or substr == ""
then
return nil
end
local pat = cache [substr]
if not pat then
local p_substr = P (substr)
local last = Cp() * p_substr * Cp() * (1 - p_substr)^0 * -1
pat = (1 - last)^0 * last
cache [substr] = pat
end
return lpegmatch (pat, str)
end
find_last() finds the last occurence of substr in the string
str, where substr can be a string of any length.
The first return value is the position of the first character of
substr in str, the second return value is the position of the
first character following substr (i.e. it equals the length of the
match plus the first return value).
Usage:
local tests = {
A = [[fooA]], --> 4, 5
[""] = [[foo]], --> nil
FOO = [[]], --> nil
K = [[foo]], --> nil
X = [[X foo X bar X baz]], --> 13, 14
XX = [[foo XX X XY bar XX baz X]], --> 17, 19
Y = [[YYYYYYYYYYYYYYYYYY]], --> 18, 19
ZZZ = [[ZZZZZZZZZZZZZZZZZZ]], --> 14, 17
--- Accepts patterns as well!
[P"X" * lpeg.R"09"^1] = [[fooX42barXxbazX]], --> 4, 7
}
for substr, str in next, tests do
print (">>", substr, str, "->", find_last (str, substr))
end
To search for the last instance of string needle in haystack:
function findLast(haystack, needle)
--Set the third arg to false to allow pattern matching
local found = haystack:reverse():find(needle:reverse(), nil, true)
if found then
return haystack:len() - needle:len() - found + 2
else
return found
end
end
print(findLast("my.string.here.", ".")) -- 15, because Lua strings are 1-indexed
print(findLast("my.string.here.", "here")) -- 11
print(findLast("my.string.here.", "there")) -- nil
If you want to search for the last instance of a pattern instead, change the last argument to find to false (or remove it).
Can be optimized but simple and does the work.
function lastIndexOf(haystack, needle)
local last_index = 0
while haystack:sub(last_index+1, haystack:len()):find(needle) ~= nil do
last_index = last_index + haystack:sub(last_index+1, haystack:len()):find(needle)
end
return last_index
end
local s = 'my.string.here.'
print(lastIndexOf(s, '%.')) -- 15
i have strings like these:
s{1,2} = 'string';
s{2,2} = 'string2';
and in workspace structure like this
U.W.string = [2 2.5 3]
I want to check (in loop) s{1,2} or s{2,2} or s{i,2} matches any structure with the same name. If so, assign values from this structure to some variable var(i). How can it be done?
Use isfields to check, if a string is the name of a field in a struct. Then use the syntax struct.(name), where name is a string to access the field. Your code might look something like:
test = struct('hello', 'world', 'count', 42, 'mean', 10);
fields = {'test', 'count';
'hello', 'text';
'more', 'less'};
values = {pi, 'dummy', -1};
for row = 1 : size(fields, 1)
for column = 1 : size(fields, 2)
if isfield(test, fields{row, column})
test.(fields{row, column}) = values{row};
end
end
end
This converts the initial struct
test =
hello: 'world'
count: 42
mean: 10
to this one
test =
hello: 'dummy'
count: 3.1416
mean: 10
A shorter implementation is achieved by removing the inner loop and giving a cell-array to isfields:
for row = 1 : size(fields, 1)
%# Note the parenthesis instead of curly braces in the next statement.
match = isfield(test, fields(row, :));
if any(match)
test.(fields{row, match}) = values{row};
end
end
Use isfield(structName,fieldName). This should do the trick:
strings{1,1} = 'foo';
strings{1,2} = 'bar';
strings{1, 3} = 'foobar';
U.W.foo = 1;
U.W.foobar = 5;
for idx = 1:length(strings)
if(isfield(U.W,strings{1,idx}))
expression = sprintf('outvar(idx) = U.W.%s',strings{1,idx});
eval(expression);
end
end
I'm sure this is simple, but I cannot find a solution ...
I would like to use a variable containing a character string as argument for a function.
x <- c(1:10)
myoptions <- "trim=0, na.rm=FALSE"
Now, something like
foo <- mean(x, myoptions)
should be the same as
foo <- mean(x, trim=0, na.rm=FALSE)
Thanks in advance!
You can use eval and parse:
foo <- eval(parse(text = paste("mean(x,", myoptions, ")")))
A more natural way to do what you want is to use do.call. For example,
R> l[["trim"]] = 0
R> l[["na.rm"]] = FALSE
R> l[["x"]] = 1:10
##Or l <- list(trim = 0, na.rm = FALSE, x = 1:10)
R> do.call(mean, l)
[1] 5.5
If for some reason you really want to use a myoptions string, you could always use strsplit to coarce it into a list form. For example,
R> y = "trim=0, na.rm=FALSE"
R> strsplit(y, ", ")
[[1]]
[1] "trim=0" "na.rm=FALSE"
R> strsplit(y, ", ")[[1]][1]
[1] "trim=0"
Here's a third answer that both uses parse, alist and do.call. My motivation for this new answer, is in the case where arguments are passed interactively from a client-side as chars. Then I guess, there is no good way around not using parse. Suggested solution with strsplit, cannot understand the context whether a comma , means next argument or next argument within an argument. strsplit does not understand context as strsplit is not a parser.
here arguments can be passed as "a=c(2,4), b=3,5" or list("c(a=(2,4)","b=3","5")
#' convert and evaluate a list of char args to a list of arguments
#'
#' #param listOfCharArgs a list of chars
#'
#' #return
#' #export
#'
#' #examples
#' myCharArgs = list('x=c(1:3,NA)',"trim=0","TRUE")
#' myArgs = callMeMaybe(myCharArgs)
#' do.call(mean,myArgs)
callMeMaybe2 = function(listOfCharArgs) {
CharArgs = unlist(listOfCharArgs)
if(is.null(CharArgs)) return(alist())
.out = eval(parse(text = paste0("alist(",
paste(parse(text=CharArgs),collapse = ","),")")))
}
myCharArgs = list('x=c(1:3,NA)',"trim=0","TRUE")
myArgs = callMeMaybe2(myCharArgs)
do.call(mean,myArgs)
[1] 2
Using all of do.call, eval and parse (combining kohske's and csgillespie's answers, and also WoDoSc's answer to 'Pass a comma separated string as a list'):
x <- c(1:10)
myoptions <- "trim = 0, na.rm = FALSE"
do.call(
what = mean,
args = append(list(x = x), eval(parse(text = paste0("list(", myoptions, ")"))))
)
This solution can be quite resilient in a more complex case, such as shown below.
myfn <- function(x, y = 0, z = 0, ...) {
print(paste("x:", x))
print(paste("y:", y))
print(paste("z:", z))
if (length(list(...)) > 0) {
print("other:")
print(list(...))
}
}
myextraargs <- paste(
"y = c(11, 14), z = 47,",
"t = data.frame(p = c('apple', 'plum'), j = c(7, 2), k = c(3, 21))"
)
do.call(
what = myfn,
args = append(
list(x = 7),
eval(parse(text = paste0("list(", myextraargs, ")")))
)
)
results in:
[1] "x: 7"
[1] "y: 11" "y: 14"
[1] "z: 47"
[1] "other:"
$t
p j k
1 apple 7 3
2 plum 2 21
...and...
myextraargs <- NULL
do.call(
what = myfn,
args = append(
list(x = 7),
eval(parse(text = paste0("list(", myextraargs, ")")))
)
)
results in
[1] "x: 7"
[1] "y: 0"
[1] "z: 0"