Im tring to normalise an Antlr AST with Java Code.
What im tring to do is
7 – 2 = 5 converted to 5 + 2 = 7
I created the following grammar already
start
: (n1=NUMBER a=ARITME^ n2=NUMBER) e=EQUALS^ n3=NUMBER {if (String.valueOf($a)=="-") /*s.th*/ ;} ;
NUMBER
: '0'..'9';
ARITME
: '+'|'-';
EQUALS
: '=';
but im not sure how to re-set the values of n1, n2 and n3 (and change the "-" to a "+") to get displayed within the AST
Related
I want to execute two commands as part of a single-line If -statement:
Though below snippet runs without error, variable $F_Akr_Completed is not set to 1, but the MsgBox() is displayed properly (with "F is 0").
$F_Akr_Completed = 0
$PID_Chi = Run($Command)
If $F_Akr_Completed = 0 And Not ProcessExists($PID_Chi) Then $F_Akr_Completed = 1 And MsgBox(1,1,"[Info] Akron parser completed. F is " & $F_Akr_Completed)
Any idea why there is no syntax-error reported when it's not functional?
There is no error, because
If x = x Then x And x
is a valid statement, and x And x is a logical expression. There are many ways you can do this, e.g.:
If Not ($F_Akr_Completed And ProcessExists($PID_Chi)) Then $F_Akr_Completed = 1 + 0 * MsgBox(1,1,"[Info] Akron parser completed. F is " & 1)
But that is a bad style of coding. AutoIt is a mostly verbose language and I recommend to seperate multiple statements.
You can also assign values using the ternary operator:
$F_Akr_Completed = (Not ($F_Akr_Completed And ProcessExists($PID_Chi))) ? 1 : 0
which is the same as
$F_Akr_Completed = Int(Not ($F_Akr_Completed And ProcessExists($PID_Chi)))
I am having trouble using dplyr's tbl_df, respectively the regular data.frame. I got a big tbl_df (500x30K) and need to filter it.
So what I would like to do is:
filter(my.tbl_df, row1>0, row10<0)
which would be similar to
df[df$row1>0 & df$row10<0,]
Works great. But I need to build the filter functions dynamically while running, so I need to access the DF/tbl_df columns by one or multiple variables.
I tried something like:
var=c("row1","row10")
op=c(">","<")
val=c(0,0)
filter(my.tbl_df, eval(parse(text=paste(var,op,val,sep="")))
Which gives me an error: not compatible with LGLSXP
This seems to be deeply rooted in the Cpp code.
I would be thankful for any hint. Also pointing out the "string to environment variable" conversion would be helpful, since I am pretty that I am doing it wrong.
With best,
Mario
This is related to this issue. In the meantime, one way could be to construct the whole expression, i.e.:
> my.tbl_df <- data.frame( row1 = -5:5, row10 = 5:-5)
> call <- parse( text = sprintf( "filter(my.tbl_df, %s)", paste(var,op,val, collapse="&") ) )
> call
expression(filter(my.tbl_df, row1 > 0&row10 < 0))
> eval( call )
row1 row10
1 1 -1
2 2 -2
3 3 -3
4 4 -4
5 5 -5
EDIT: Thank to Joe's advice, I will make my question more specific. Actually I need to code a function in Stata which takes variables A,B,C,D,... as inputs and a variable Y as output which can be evaluated with usual Stata functions/commands like "generate dummy=2*myfun(X) if ..."
The function itself contains numerical calculations. A pseudo Stata code will look like
myfun(X)
gen Y=0.5*X if X==1
replace Y=31-X if X==2
replace Y=X-2 if X==3
.... a long list
return(Y)
Notice that X can be a huge set of different Stata variables and the numerical calculations are rather long inside the function. That's why I would like to use a function. I guess that the native "program" command in Stata is not suitable for this type of problem because it cannot take variables as input/output.
(ANSWER TO ORIGINAL QUESTION)
I have never used SAS, but at a wild guess you want something like
foreach v in A B C D {
gen test`v' = 0.5 * (`v' == 1) + 0.6 * (`v' == 2) + 0.7 * (`v' == 3)
}
or
foreach v in A B C D {
gen test`v' = cond(`v' == 1, 0.5, cond(`v' == 2, 0.6, cond(`v' == 3, 0.7, .)))
}
But hang on; that middle line also looks like
gen test`v' = (4 + `v') / 10
(ANSWER TO COMPLETELY DIFFERENT REVISED QUESTION)
This can be done in various ways. As above you could have a loop
foreach v in A B C D {
gen test`v' = 0.5 * `v' if `v' == 1
replace test`v' = 31 - `v' if `v' == 2
replace test`v' = `v' - 2 if `v' == 3
}
The question says "I guess that the native "program" command in Stata is not suitable for this type of problem because it cannot take variables as input/output." That guess is completely incorrect. You could write a program to do this too. This example is schematic, not definitive. A real program would include more checks and error messages to match any incorrect input. For detailed advice, you really need to read the documentation. One answer on SO can't teach you all you need to know even to write simple Stata programs. In any case, the example is evidently frivolous and/or incomplete, so a complete working example would be pointless or impossible.
program myweirdexample
version 13
syntax varlist(numeric), Generate(namelist)
local nold : word count `varlist'
local nnew : word count `generate'
if `nold' != `nnew' {
di as err "`generate' does not match `varlist'"
exit 198
}
local i = 1
quietly foreach v of local varlist {
local new : word `i' of `generate'
gen `new' = 0.5 * `v' if `v' == 1
replace `new' = 31 - `v' if `v' == 2
replace `new' = `v' - 2 if `v' == 3
local ++i
}
end
Footnote on terminology: The question uses the term function more broadly than it is used in Stata. In Stata, commands and functions are distinct; "function" is not a synonym for command.
Second footnote: Check out recode. It may be what you need, but it is best for mapping integer codes to other integer codes.
Third footnote: An example of a needed check is that the argument of generate() should be variable names that are legal and new.
i trying to assign a row number and a Set-number for List, but Set Number containing wrong number of rows in one set.
var objx = new List<x>();
var i = 0;
var r = 1;
objY.ForEach(x => objx .Add(new x
{
RowNumber = ++i,
DatabaseID= x.QuestionID,
SetID= i == 5 ? r++ : i % 5 == 0 ? r += 1 : r
}));
for Above code like objY Contains 23 rows, and i want to break 23 rows in 5-5 set.
so above code will give the sequence like[Consider only RowNumber]
[1 2 3 4 5][6 7 8 9][ 10 11 12 13 14 ].......
its a valid as by the logic
and if i change the logic for Setid as
SetID= i % 5 == 0 ? r += 1 : r
Result Will come Like
[1 2 3 4 ][5 6 7 8 9][10 11 12 13 14].
Again correct output of code
but expected for set of 5.
[1 2 3 4 5][ 6 7 8 9 10].........
What i missing.............
i should have taken my Maths class very Serious.
I think you want something like this:
var objX = objY.Select((x, i) => new { ObjX = x, Index = i })
.GroupBy(x => x.Index / 5)
.Select((g, i) =>
g.Select(x => new objx
{
RowNumber = x.Index + 1
DatabaseID = x.ObjX.QuestionID,
SetID = i + 1
}).ToList())
.ToList();
Note that i'm grouping by x.Index / 5 to ensure that every group has 5 items.
Here's a demo.
Update
it will be very helpful,if you can explain your logic
Where should i start? I'm using Linq methods to select and group the original list to create a new List<List<ObjX>> where every inner list has maximum 5 elements(less in the last if the total-count is not dividable by 5).
Enumerable.Select enables to project something from the input sequence to create something new. This method is comparable to a variable in a loop. In this case i project an anonymous type with the original object and the index of it in the list(Select has an overload that incorporates the index). I create this anonymous type to simply the query and because i need the index later in the GroupBy``.
Enumerable.GroupBy enables to group the elements in a sequence by a specified key. This key can be anything which is derivable from the element. Here i'm using the index two build groups of a maximum size of 5:
.GroupBy(x => x.Index / 5)
That works because integer division in C# (or C) results always in an int, where the remainder is truncated(unlike VB.NET btw), so 3/4 results in 0. You can use this fact to build groups of the specified size.
Then i use Select on the groups to create the inner lists, again by using the index-overload to be able to set the SetId of the group:
.Select((g, i) =>
g.Select(x => new objx
{
RowNumber = x.Index + 1
DatabaseID = x.ObjX.QuestionID,
SetID = i + 1
}).ToList())
The last step is using ToList on the IEnumerable<List<ObjX>> to create the final List<List<ObX>>. That also "materializes" the query. Have a look at deferred execution and especially Jon Skeets blog to learn more.
This is not homework, but an old exam question. I am curious to see the answer.
We are given an alphabet S={0,1,2,3,4,5,6,7,8,9,+}. Define the language L as the set of strings w from this alphabet such that w is in L if:
a) w is a number such as 42 or w is the (finite) sum of numbers such as 34 + 16 or 34 + 2 + 10
and
b) The number represented by w is divisible by 3.
Write a regular expression (and a DFA) for L.
This should work:
^(?:0|(?:(?:[369]|[147](?:0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0\+)*[147]0*(?:\+?(?:0\
+)*[369]0*)*\+?(?:0\+)*[258])*(?:0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0\+)*[258]|0*(?:
\+?(?:0\+)*[369]0*)*\+?(?:0\+)*[147]0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0\+)*[147])|[
258](?:0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0\+)*[258]0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0
\+)*[147])*(?:0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0\+)*[147]|0*(?:\+?(?:0\+)*[369]0*)
*\+?(?:0\+)*[258]0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0\+)*[258]))0*)+)(?:\+(?:0|(?:(?
:[369]|[147](?:0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0\+)*[147]0*(?:\+?(?:0\+)*[369]0*)
*\+?(?:0\+)*[258])*(?:0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0\+)*[258]|0*(?:\+?(?:0\+)*
[369]0*)*\+?(?:0\+)*[147]0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0\+)*[147])|[258](?:0*(?
:\+?(?:0\+)*[369]0*)*\+?(?:0\+)*[258]0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0\+)*[147])*
(?:0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0\+)*[147]|0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0\+)
*[258]0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0\+)*[258]))0*)+))*$
It works by having three states representing the sum of the digits so far modulo 3. It disallows leading zeros on numbers, and plus signs at the start and end of the string, as well as two consecutive plus signs.
Generation of regular expression and test bed:
a = r'0*(?:\+?(?:0\+)*[369]0*)*\+?(?:0\+)*'
b = r'a[147]'
c = r'a[258]'
r1 = '[369]|[147](?:bc)*(?:c|bb)|[258](?:cb)*(?:b|cc)'
r2 = '(?:0|(?:(?:' + r1 + ')0*)+)'
r3 = '^' + r2 + r'(?:\+' + r2 + ')*$'
r = r3.replace('b', b).replace('c', c).replace('a', a)
print r
# Test on 10000 examples.
import random, re
random.seed(1)
r = re.compile(r)
for _ in range(10000):
x = ''.join(random.choice('0123456789+') for j in range(random.randint(1,50)))
if re.search(r'(?:\+|^)(?:\+|0[0-9])|\+$', x):
valid = False
else:
valid = eval(x) % 3 == 0
result = re.match(r, x) is not None
if result != valid:
print 'Failed for ' + x
Note that my memory of DFA syntax is woefully out of date, so my answer is undoubtedly a little broken. Hopefully this gives you a general idea. I've chosen to ignore + completely. As AmirW states, abc+def and abcdef are the same for divisibility purposes.
Accept state is C.
A=1,4,7,BB,AC,CA
B=2,5,8,AA,BC,CB
C=0,3,6,9,AB,BA,CC
Notice that the above language uses all 9 possible ABC pairings. It will always end at either A,B,or C, and the fact that every variable use is paired means that each iteration of processing will shorten the string of variables.
Example:
1490 = AACC = BCC = BC = B (Fail)
1491 = AACA = BCA = BA = C (Success)
Not a full solution, just an idea:
(B) alone: The "plus" signs don't matter here. abc + def is the same as abcdef for the sake of divisibility by 3. For the latter case, there is a regexp here: http://blog.vkistudios.com/index.cfm/2008/12/30/Regular-Expression-to-determine-if-a-base-10-number-is-divisible-by-3
to combine this with requirement (A), we can take the solution of (B) and modify it:
First read character must be in 0..9 (not a plus)
Input must not end with a plus, so: Duplicate each state (will use S for the original state and S' for the duplicate to distinguish between them). If we're in state S and we read a plus we'll move to S'.
When reading a number we'll go to the new state as if we were in S. S' states cannot accept (another) plus.
Also, S' is not "accept state" even if S is. (because input must not end with a plus).