CODE WON'T RUN
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AMPL Google Group
Aug 19, 2022, 4:06:13 PM8/19/22
to AMPL Modeling Language
When you try to solve, you are seeing this error message:
According to your definition in the model, constraint night_morning[1,7,1] should be this:
But the error message is telling you that the variable assignment[7,1,1,3] does not exist. To see why, observe that "var assignment" is defined as follows,
The four indexing sets are given as follows by the data:
Thus assignment[7,1,1,3] does not exist because 7 is not in the set I. Maybe you meant to write "assignment[i,3,k,l] + assignment[i+1,1,k,l]".
error processing constraint night_morning[1,7,1]:
invalid subscript assignment[7,1,1,3]According to your definition in the model, constraint night_morning[1,7,1] should be this:
assignment[7,1,1,3] + assignment[7,2,1,1] <= 1
But the error message is telling you that the variable assignment[7,1,1,3] does not exist. To see why, observe that "var assignment" is defined as follows,
var assignment {i in I, j in J, k in K, l in L} binary;The four indexing sets are given as follows by the data:
ampl: display I,J,K,L; set I := 1 2 3 4 5 6; set J := 1 2 3; set K := 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; set L := 1 2 3;
Thus assignment[7,1,1,3] does not exist because 7 is not in the set I. Maybe you meant to write "assignment[i,3,k,l] + assignment[i+1,1,k,l]".
--
Robert Fourer
am...@googlegroups.com
Eizee Mariano
Aug 20, 2022, 9:25:53 AM8/20/22
to am...@googlegroups.com
Hello Sir! Thank you for the response. I am now getting this error when running my code and data file. Please help. The first photo is my data file and the second photo is the mod file. The last photo is the mathematical code and constraints as our basis Sir.
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AMPL Google Group
Aug 21, 2022, 7:59:47 PM8/21/22
to AMPL Modeling Language
You define
param X {DAYS, MSHIFT, NURSES} > 0;
which says there must be a positive value X[i,j,k] for every combination of i in DAYS, j in MSHIFT, and k in NURSES. Your AMPL data does not give all these values. So AMPL gets to the end of the X data before all the values have been read, and as a result it gives the error message "expected ; . or number". There is a similar problem with Y and Z.
Really the problem is not with the data, however, but with the definition of the parameters. Instead of X, Y, and Z, you can simply define
param needed {DAYS, SHIFTS} > 0;
where needed[i,j] is the number of nurses needed in shift j on day i. The shifts are 1 (morning), 2 (afternoon), and 3 (night). Using this definition, the sets MSHIFT, ASHIFT, and NSHIFT aren't needed (and in fact you aren't using them for anything in your model). In constraint morning_shift, X[i,1,k] can be replaced by needed[i,1], and similarly for constraints afternoon_shift and night_shift. The data for param needed can be given in a common AMPL table formal:
param X {DAYS, MSHIFT, NURSES} > 0;
which says there must be a positive value X[i,j,k] for every combination of i in DAYS, j in MSHIFT, and k in NURSES. Your AMPL data does not give all these values. So AMPL gets to the end of the X data before all the values have been read, and as a result it gives the error message "expected ; . or number". There is a similar problem with Y and Z.
Really the problem is not with the data, however, but with the definition of the parameters. Instead of X, Y, and Z, you can simply define
param needed {DAYS, SHIFTS} > 0;
where needed[i,j] is the number of nurses needed in shift j on day i. The shifts are 1 (morning), 2 (afternoon), and 3 (night). Using this definition, the sets MSHIFT, ASHIFT, and NSHIFT aren't needed (and in fact you aren't using them for anything in your model). In constraint morning_shift, X[i,1,k] can be replaced by needed[i,1], and similarly for constraints afternoon_shift and night_shift. The data for param needed can be given in a common AMPL table formal:
param needed:
1 2 3 :=
1 3 4 2
2 3 4 5
3 4 3 4
4 4 3 3
5 3 4 4
6 3 3 2 ;--
Robert Fourer
am...@googlegroups.com
On Sat, Aug 20, 2022 at 1:26 PM UTC, AMPL Modeling Language <am...@googlegroups.com> wrote:
Hello Sir! Thank you for the response. I am now getting this error when running my code and data file. Please help. The first photo is my data file and the second photo is the mod file. The last photo is the mathematical code and constraints as our basis Sir.
On Fri, Aug 19, 2022 at 8:05 PM UTC, AMPL Google Group <am...@googlegroups.com> wrote:
When you try to solve, you are seeing this error message:error processing constraint night_morning[1,7,1]: invalid subscript assignment[7,1,1,3]
According to your definition in the model, constraint night_morning[1,7,1] should be this:assignment[7,1,1,3] + assignment[7,2,1,1] <= 1
But the error message is telling you that the variable assignment[7,1,1,3] does not exist. To see why, observe that "var assignment" is defined as follows,var assignment {i in I, j in J, k in K, l in L} binary;
The four indexing sets are given as follows by the data:ampl: display I,J,K,L; set I := 1 2 3 4 5 6; set J := 1 2 3; set K := 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; set L := 1 2 3;
Thus assignment[7,1,1,3] does not exist because 7 is not in the set I. Maybe you meant to write "assignment[i,3,k,l] + assignment[i+1,1,k,l]".
--
Robert Fourer
am...@googlegroups.com
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