Doing a small example, I want to insert a symbol within a list at a certain pozition
domains
element = symbol
list = element*
position = integer
predicates
insert (element, position, list, list) %(input,input,input,output)
clauses
insert (E,_,[],[E]).
insert (E, 1,[H|T],[E|[H|T]]). %(I insert E on the "first" position)
% I get errors how E and T are not bound. I have no idea how to make them bound
insert (E,P,[H|T],[H1|T1]) :-
P > 1,
P1 = P - 1,
insert (E,P1,T,T1).
It doesn't work ... but I don't know why. Well it kinda works. I would like it to show me outputList = [NEW_LIST] instead of showing every symbolName=_ and then outputList = [_,_,_,_].
Apparently there is some problem with symbol data type, if I use integer, it fixes itself.
Also, this is esential:
domains
element = integer
list = element*
position = integer
predicates
insert (element, position, list, list) %(input,input,input,output)
clauses
insert (E,_,[],[E]).
insert (E, 1,[H|T],[E|[H|T]]).
insert (E,P,[H|T],[H|T1]) :- % has to be "H" (or anything else) in both
P > 1, % so prolog understands what we are trying to do
P1 = P - 1, % don't really understand why though
insert (E,P1,T,T1). % I might be wrong
Related
I am a new SystemVerilog user and I have faced a strange (from my point of view) behavior of combination of unique method called for fixed array with with operator.
module test();
int arr[12] = '{1,2,1,2,3,4,5,8,9,10,10,8};
int q[$]
initial begin
q = arr.unique() with (item > 5 ? item : 0);
$display("the result is %p",q);
end
I've expected to get queue {8,9,10} but instead I have got {1,8,9,10}.
Why there is a one at the index 0 ?
You are trying to combine the operation of the find method with unique. Unfortunately, it does not work the way you expect. unique returns the element, not the expression in the with clause, which is 0 for elements 1,2,3,4 and 5. The simulator could have chosen any of those elements to represent the unique value for 0(and different simulators do pick different values)
You need to write them separately:
module test();
int arr[$] = '{1,2,1,2,3,4,5,8,9,10,10,8};
int q[$]
initial begin
arr = arr.find() with (item > 5);
q = arr.unique();
$display("the result is %p",q);
end
Update explaining the original results
The with clause generates a list of values to check for uniqueness
'{0,0,0,0,0,0,0,8,9,10,10,8};
^. ^ ^ ^
Assuming the simulator chooses the first occurrence of a replicated value to remain, then it returns {arr[0], arr[7], arr[8], arr[9]} from the original array, which is {1,8,9,10}
I want to make subprogram for adding array's elements with Ada.
subprogram "Add_Data" have 3 parameters-
first parameter = generic type array (array of INTEGER or array of REAL)
second parameter = INTEGER (size of array)
third parameter = generic type sum (array of INTEGER -> sum will be INTEGER, array of REAL -> sum will be REAL)
I programmed it from ideone.com.
(I want to see just result by array of INTEGER. After that, I will test by array of REAL)
With Ada.Text_IO; Use Ada.Text_IO;
With Ada.Integer_Text_IO; Use Ada.Integer_Text_IO;
procedure test is
generic
type T is private;
type Tarr is array (INTEGER range <>) of T;
--function "+" (A,B : T) return T;
--function "+" (A, B : T) return T is
--begin
-- return (A+B);
--end "+";
procedure Add_Data(X : in Tarr; Y : in INTEGER; Z : in out T);
procedure Add_Data(X : in Tarr; Y : in INTEGER; Z : in out T) is
temp : T;
count : INTEGER;
begin
count := 1;
loop
temp :=temp+ X(count); //<-This is problem.
count := count + 1;
if count > Y then
exit;
end if;
end loop;
Z:=temp;
end Add_Data;
type intArray is array (INTEGER range <>) of INTEGER;
intArr : intArray := (1=>2, 2=>10, 3=>20, 4=>30, 5=>8);
sum : INTEGER;
procedure intAdd is new Add_Data(Tarr=>intArray, T=>INTEGER);
begin
sum := 0;
intAdd(intArr, 5, sum);
put (sum);
end test;
when I don't overload operator "+", It makes error.
"There is no applicable operator "+" for private type "T" defined."
What can I do for this?
If a generic’s formal type is private, then nothing in the generic can assume anything about the type except that it can be assigned (:=) and that it can be compared for equality (=) and inequality (/=). In particular, no other operators (e.g. +) are available in the generic unless you provide them.
The way to do that is
generic
type T is private;
with function "+" (L, R : T) return T is <>;
This tells the compiler that (a) there is a function "+" which takes two T’s and returns a T; and (b) if the actual T has an operator "+" which matches that profile, to allow it as the default.
So, you could say
procedure intAdd is new Add_Data (T => Integer, ...
or, if you didn’t feel like using the default,
procedure intAdd is new Add_Data (T => Integer, "+" => "+", ...
In addition to not knowing how to declare a generic formal subprogram (Wright has shown how to do this for functions), your code has a number of other issues that, if addressed, might help you move from someone who thinks in another language and translates it into Ada into someone who actually uses Ada. Presuming that you want to become such a person, I will point some of these out.
You declare your array types using Integer range <>. It's more common in Ada to use Positive range <>, because people usually refer to positions starting from 1: 1st, 2nd, 3rd, ...
Generics are used for code reuse, and in real life, such code is often used by people other than the original author. It is good practice not to make unstated assumptions about the values clients will pass to your operations. You assume that, for Y > 0, for all I in 1 .. Y => I in X'range and for Y < 1, 1 in X'range. While this is true for the values you use, it's unlikely to be true for all uses of the procedure. For example, when an array is used as a sequence, as it is here, the indices are immaterial, so it's more natural to write your array aggreate as (2, 10, 20, 30, 8). If I do that, Intarr'First = Integer'First and Intarr'Last = Integer'First + 4, both of which are negative. Attempting to index this with 1 will raise Constraint_Error.
Y is declared as Integer, which means that zero and negative values are acceptable. What does it mean to pass -12 to Y? Ada's subtypes help here; if you declare Y as Positive, trying to pass non-positive values to it will fail.
Z is declared mode in out, but the input value is not referenced. This would be better as mode out.
Y is not needed. Ada has real arrays; they carry their bounds around with them as X'First, X'Last, and X'Length. Trying to index an array outside its bounds is an error (no buffer overflow vulnerabilities are possible). The usual way to iterate over an array is with the 'range attribute:
for I in X'range loop
This ensures that I is always a valid index into X.
Temp is not initialized, so it will normally be initialized to "stack junk". You should expect to get different results for different calls with the same inputs.
Instead of
if count > Y then
exit;
end if;
it's more usual to write exit when Count > Y;
Since your procedure produces a single, scalar output, it would be more natural for it to be a function:
generic -- Sum
type T is private;
Zero : T;
type T_List is array (Positive range <>) of T;
with function "+" (Left : T; Right : T) return T is <>;
function Sum (X : T_List) return T;
function Sum (X : T_List) return T is
Result : T := Zero;
begin -- Sum
Add_All : for I in X'range loop
Result := Result + X (I);
end loop Add_All;
return Result;
end Sum;
HTH
I'm attempting my first constraint programming with minizinc. I'm trying to create a schedule, with n slots and n people, with a different person allocated to each slot. I'm using an array of var int to model the schedule, usingalldifferent() to ensure a different person in each slot.
A separate array of size n, names contains their names, as below:
% Pseudo enum
set of int: NameIndex = 1..2;
int: Forename = 1;
int: Surname = 2;
int: n = 4; % Number of slots and people
set of int: slots = 1..n;
array[slots, NameIndex] of string: names = [| "John", "Doe"
| "Ann", "Jones"
| "Fred", "Doe"
| "Barry", "Doe" |];
% The schedule
array[slots] of var slots: schedule;
% Every person is scheduled:
include "alldifferent.mzn";
constraint alldifferent(schedule);
% How to constrain by a value from names, say alphabetic order by forename.
% Want to compare each value in schedule to the next one.
%constraint forall (i in 1..n-1) (names[schedule[i],Forename] < names[schedule[i+1],Forename]);
solve satisfy;
output [show(i) ++ ": " ++ show(names[schedule[i], Forename]) ++ " " ++ show(names[schedule[i], Surname]) ++ "\n"
| i in slots]
% should be:
% | i in schedule]
How can I constrain schdule by values from names? In my (broken) example above, when the forall constraint is uncommented, i get (using the Minizinc IDE):
in call 'forall'
in array comprehension expression
with i = 1
in binary '<' operator expression
in array access
cannot find matching declaration
I follow the error until not understanding which declaration cannot be found. The output block show()s values from names quite happily when I index into array from the schdule value.
What am I missing? Is there a better way to model the names? I'm hoping to extend names to additional 'attributes' of people and create additional constraints. I'm sure both the model and my forall constraint are quite naive!
The problem is that MiniZinc don't have much support for strings; and specific for your example: there's no support for comparing strings ("<").
That said, there are some plans to support var strings (i.e. using strings as decision variables), but I don't know the exact status when it will be released.
Here's a very simple fix but it requires some preprocessing:
1) Create a new array which includes the (ordering) index of each name:
array[slots] of int: names_ix = [4, % John Doe
1, % Ann Jones
3, % Fred Doe
2, % Barry Doe
];
2) Change the ordering constraint to use this new array
constraint
forall (i in 1..n-1) (
names_ix[schedule[i]] <= names_ix[schedule[i+1]]
);
[There's a more complex variant that requires that you convert each character in the names to integers (in a matrix of "var int"), and then require that the words - as collection of integers - are ordered. Note that this tends to be quite messy, for example to handle strings of different lengths etc.]
M=read_csv("Gradesheets\MECN2073_2014.csv")
disp(size(M,1))
for x=1:1:size(M,1)
StudNum=M(x,1)
Grd=M(x,2) // Grd is grade column in gradesheets hence x,2 (column 2 of Grd )
if find(StudNum==StudentNumbers)>0 then disp("Exists")
H = [StudNum]
StudentNumbers = [StudentNumbers;StudNum]
end
end
This is where i get error:
Undefined operation for the given operands.
check or define function %s_f_c for overloading.
at line 38 of exec file called by :
I assume that StudentNumbers is the vector containing all your existing students right? If so, try the code below and let me know what you get.
M=read_csv("Gradesheets\MECN2073_2014.csv")
storing = [];
for i=1:size(M,1)
StudNum=M(i,1)
if find(StudNum==StudentNumbers(i)) == 1
disp("Exists");
storing = [storing;StudNum];
end
end
I am trying to assign valuable, which is number and given by for loop, to the name of structure field. For example, I would like to do as following,
A.bx, where A is name of structure(= char), b is part of field name ( = char) and x is valuable given by for loop. A and b is fixed or predefined.
Any comment is appreciated !
genvarname(str,list) generates a valid variable name in str [a string] in which at each iteration value in str is different from the exclusion list
And fieldname(S) returns a list of all the names of the field already in the structure S (use it to create a exclusion list)
Here is a code for what you want:
A = struct ();
for i = 1:5
A.(genvarname ('b', fieldnames (A))) = i;
end
Read about 1. genvarname(str,list) 2. fieldnames(S)
You can name you struct fields using simple sprintf
A = struct()
for ii = 1:10
fn = sprintf('b%d', ii );
A.(fn) = ii; % use the struct
end
I tend to agree with sebastian that suggested using arrays or cells over this type of field naming. In addition to cells and arrays you might find containers.Map to be very versatile and useful.