In SAS if I have a string or an Array like the following,
array x[4] $1 ('A' 'B' 'C' 'D');
I need to generate all "Unique" permutations of the elements like the following,
[ABCD]
[ABC]
[BCD]
[ACD]
[ABD]
[AB]
[AC]
[AD]
[BC]
[BD]
[CD]
[A]
[B]
[C]
[D]
Is there a function in SAS for generating all possible combinations of the array?
Assumption: I believe you are looking for combinations and not permutations, so the order does not matter, BA and AB are same thing.
Use call allcomb subroutine and comb function to find out the possible combinations.
Read more about allcomb and comb here
http://support.sas.com/documentation/cdl/en/lefunctionsref/63354/HTML/default/viewer.htm#p0yx35py6pk47nn1vyrczffzrw25.htm
and here
http://support.sas.com/documentation/cdl/en/lrdict/64316/HTML/default/viewer.htm#a001009658.htm
In short -
call allcomb subroutine gives the possible combinations out of n elements when r of them are taken and
comb function gives you how many combinations it would be when out of n elements r of them are taken at a time.
data test(keep=my_string);
length my_string $50.;
array a[4] $ ('A' 'B' 'C' 'D');
n = dim(a);
do k=1 to n;
do j=1 to comb(n,k);
call allcomb(j,k,of a[*]);
do i = 1 to k;
if i=1 then do; my_string="";counter=0;end;
counter=counter+1;
my_string=cat(compress(my_string),compress(a[i]));
if counter=k then output;
end;
end;
end;
run;
A slightly different take on this is to use proc summary.
Create a dummy dataset. Assign each element of the array to a variable so we can feed it into proc summary:
data tmp;
array arr[*] a b c d (1 1 1 1);
run;
Run proc summary.
proc summary data=tmp noprint missing;
class a b c d;
output out=combinations;
run;
You can also use the ways or types statements in proc summary to limit any combinations you may want.
Now the interesting side effect of doing this is that you get the _type_ column in the output dataset as well. In the example above the following values would be assigned:
D = 1
C = 2
B = 4
A = 8
So if the _type_ value in the output dataset is 13, then we know that the row was generated by combining A, B and D (8 + 4 + 1).
Here is a quick script that will find the combinations of the individual characters within a string. This could be easily adapted to work with arrays if you prefer. Rather than using the combinational functions and call routines (all*, lex*, ran*) this approach creates the permutations by using the binary representation of integers up to 2**len. I prefer this approach as I think it demonstrates what is happening, is more transparent and doesn't change the order of the array assignments.
data have;
str = "123456"; output;
str = "ABCD"; output;
run;
data want;
set have;
length comb $20.;
len = length(str);
/* Loop through all possible permutations */
do _i = 0 to 2**len - 1;
/* Store the current iteration number in binary */
_bin = putn(_i, "binary" || put(len, best.) || ".");
/* Initialise an empty output variable */
comb = "";
/* Loop through each value in the input string */
do _k = 1 to len;
/* Check if the kth digit of the binary representation is 1 */
/* And if so add the kth input character to the output */
if substr(_bin, _k, 1) = "1" then
comb = cats(comb, substr(str, _k, 1));
end;
output;
end;
/* Clean up temporary variables, commented so you can see what's happening */
/* drop _:; */
run;
If you do want permutations then a similar approach is possible using factoradic representations of the numbers. But, I would recommend that you use a combinational function instead as the conversions would be much more involved. It's probably quite a nice coding exercise for learning though.
It would be great if SAS had a function for reducing strings by boolean patterns, but it probably wouldn't get much use.
bsubstr("ABCD", "1010") --> "AC"
bsubstr("ABCD", "1110") --> "ABC"
bsubstr("ABCD", "0001") --> "D"
SAS has in-built functions to calculate combinations & permutations, allcomb and allperm.
SAS Documentation for ALLCOMB function : http://support.sas.com/documentation/cdl/en/lrdict/64316/HTML/default/viewer.htm#a003112305.htm
Related
I have been working on randomly selecting items within an array. Below, I have outlined my process. I have made it to successfully step 6 (with many data checks), but for some reason, when I reference the array, I receive a value of zero. This has been confusing because even when I check the raw sorted data note a certain value, the value retrieved is zero. Additionally, I ran a VNAME to see which variable it was pulling and it corresponded to the correct place within the array. Does anyone know why I am returning a zero value from the array?
*STEP 1: Set all non-codes to zero;
ARRAY CEREAL [337] ha_DTQ02_1-ha_DTQ02_337;
DO i=1 to 337;
if CEREAL[i]=88888.00 THEN CEREAL[i]=0;
END;
*STEP 2: Sort so that all zero values come first and food codes come last;
call SORTN(ha_DTQ02_1-ha_DTQ02_337);
*STEP 3: Rename array in reverse order so that zeros come last and codes are first. Sort function above only works in ascending order;
RENAME ha_DTQ02_1- ha_DTQ02_337=ha_DTQ02_337-ha_DTQ02_1;
*STEP 4: Count number of cereals selected;
ARRAY CEREALS[337]ha_DTQ02_1-ha_DTQ02_337;
NUMCEREALS=0;
DO i=1 to 337;
IF CEREALS[i] NOT IN (.,0) THEN NUMCEREALS+1;
END;
*STEP 5: get a random number between those two numbers- this works just fine;
IF NUMCEREALS NE 0 THEN rand1 = rand('integer', 1, numCereals);
*ensure that your second random number isn't the same as the first random number;
if NUMCEREALS ge 2 then do until(rand2 ne rand1);
rand2 = rand('integer', 1, numCereals);
end;
*STEP 6: Pull value from array using random number.;
Note: This is where I am stuck. I have tried alternative code where I recreated a new array and tried to pull the values from that new array. I have also tried placing the code directly below before closing the do loop. When the code does run, the value for these variables is zero. After many data checks, steps 1-5 work well and achieve their goals.
dtd020Af = CEREALS (rand1);
dtd020Bf = CEREALS (rand2);
OPTIONS NOFMTERR;
run;
The SORTN call routine needs the OF operator in order to utilize a name list.
call SORTN(of ha_DTQ02_1-ha_DTQ02_337);
A keen eye on the LOG window should have shown you the WARNING
3214 call SORTN(ha_DTQ02_1-ha_DTQ02_337);
-----
134
WARNING 134-185: Argument #1 is an expression, which cannot be updated by the SORTN subroutine
call.
You can't rename variables during run-time and reference the value with the new names.
You have declared an ARRAY listing the variables in 1..337 order. Check, that's good.
You CAN declare a second ARRAY listing the variables in reverse 337..1 order!
You also do not want to use a variable that might be missing, rand2, as a index value.
Suggested code:
data have;
call streaminit(123);
do id = 1 to 100;
array X X1-X337;
do over X;
if rand('uniform') < 0.75 then X = 88888;
else
X = rand('integer',1,10);
if id=50 then if _I_ ne 10 then X=88888; else X=5;
end;
OUTPUT;
end;
run;
data want;
set have;
ARRAY CEREAL X1-X337;
DO i=1 to DIM(CEREAL);
if CEREAL[i]=88888.00 THEN CEREAL[i]=0;
END;
* sort the variables that comprise the CEREAL array;
call SORTN(of CEREAL(*));
* second array to reference variables in reverse order;
array CEREAL_REVERSE x337-x1;
* count how many non-missing/non-zero values at the end of the sorted variables;
DO i=1 to DIM(CEREAL);
IF CEREAL_REVERSE[i] IN (.,0) then leave;
NUMCEREALS = i;
END;
IF NUMCEREALS NE 0 THEN rand1 = rand('integer', 1, numCereals);
if NUMCEREALS ge 2 then
do until(rand2 ne rand1);
rand2 = rand('integer', 1, numCereals);
end;
* assign random selection if warranted;
if NUMCEREALS > 0 then dtd020Af = CEREAL_REVERSE (rand1);
if NUMCEREALS > 1 then dtd020Bf = CEREAL_REVERSE (rand2);
run;
I have a big SAS table, let's describe the columns as, A nd B columns in character format and all other columns are vairable in numerical format (every variable has a different name) with unknow amounth length N, like:
A B Name1 Name2 Name3 .... NameN
-------------------------------------------------
Char Char Number1 Number2 Number3 ..... NumberN
.................................................
.................................................
The goal is that the numerical array Name1-NameN will sum up downward through the Class=B (By B),
So the final table will look like this:
A B Name1 Name2 Name3 .... NameN
----------------------------------------
Char Char Sum1 Sum2 Sum3 ..... SumN
........................................
........................................
To do this sum-up, I described 2 arrays. The first one is:
array Varr {*} _numeric_; /* it reads only numerical columns */
Then I described another array with the same length (Summ1-SummN) to do the sum-up process.
The thing is that I can only describe the length of this new array manually. For example, if there are 80 numerical values, then I have to write manually like:
array summ {80} Summ1-Summ80;
The code works when I write it manually. But instead I want to write something like
array summ {&N} Summ1-Summ&N; /* &N is the dimension of the array Varr */
I tried with do-loop and dim(Varr) under the array in many different ways like:
data want;
array Varr {*} _numeric_;
do i=1 to dim(Varr);
N+1 ;
end;
%put &N;
array Summ {&N} Summ1-Summ&N;
retain Summ;
if first.B then do i=1 to dim(varr); summ(i)=varr(i) ;end;
else do i =1 to dim(varr); summ(i) = summ(i) + varr(i) ; varr(i)=summ(i); end;
drop Summ1-Summ&N;
run;
But it doesn't work. Any idea about how to bring the length of the first array to the second array?
You need to calculate and store the number of numeric variables in a previous step. The easiest way is to use the dictionary.columns metadata table, available in proc sql. This contains all column details for a given dataset, including the type (num or char), you therefore just need to count the number of columns where the type is 'num'.
The code below does just that and stores the result in a macro variable, &N. using the into : functionality. I've also used the functions left and put to remove leading blanks from the macro variable, otherwise you'll encounter problems when putting summ1-summ&N.
I've also added a 2nd solution based on your answer, but will be more efficient as it doesn't read in any records, only the column details
proc sql noprint;
select left(put(count(*),best12.)) into :N
from dictionary.columns
where libname='SASHELP' and memname='CLASS' and type='num';
quit;
%put Numeric variables = &N.;
/*****************************************/
/* alternative solution */
data _null_;
set sashelp.class (obs=0);
array temp{*} _numeric_;
call symputx('N',dim(temp));
run;
%put Numeric variables = &N.;
Now I found another solution with a little modification of the solution from #kl78
Before when I tried with call symput ('N',dim(varr)); I forgot to change the numeric format and to remove the uneccessary spaces. When I run it without format, the code tried to find Summ_____87, so it gave error.
Now I run it with format, call symput ('N',put(dim(varr),2.)); the code can find Summ87, so it is totally sucessfull now.
I am trying to create a macro that compute the inner(dot) product of a vector and a matrix.
Y*X*t(Y) ## equivalent to the Sum(yi*Xij*yj)
I don't have IML, so I try to do it using array manipulation.
How to create a multidimensional array from the data to avoid index
translation within single array.
How to debug my loop, or at least print some variable to control my program?
How to delete temporary variables?
I am a SAS newbie, but this is what I have tried so far:
%macro dot_product(X = ,y=, value= );
/* read number of rows */
%let X_id=%sysfunc(open(&X));
%let nrows=%sysfunc(attrn(&X_id,nobs));
%let rc=%sysfunc(close(&X_id));
data &X.;
set &X.;
array arr_X{*} _numeric_;
set &y.;
array arr_y{*} _numeric_;
do i = 1 to &nrows;
do j = 1 to &nrows;
value + arr_y[i]*arr_X[j + &nrows*(i-1)]*arr_y[j];
end;
end;
run;
%mend;
When I run this :
%dot_product(X=X,y=y,value=val);
I get this error :
ERROR: Array subscript out of range at line 314 column 158.
I am using this to generate data :
data X;
array myCols{*} col1-col5;
do i = 1 to 5;
do j = 1 to dim(myCols);
myCols{j}=ranuni(123);
end;
output;
end;
drop i j;
run;
/* create a vector y */
data y;
array myCols{*} col1-col5;
do j = 1 to dim(myCols);
myCols{j}=ranuni(123);
end;
output;
drop j;
run;
Thanks in advance for your help or any idea to debug my data.
Edit: The following relates to the description of the question, how to evaluate a quadratic form using dot, inner or scalar products. The actual code is nearly fine. end edit
If you want to reduce it to dot products, then your value is the dot product of the linearization of X_ij and the same linearization applied to Z_ij=Y_i*Y_j.
The other way is to portion X_ij into its rows or columns depending on the linearization of the matrix, and compute separate dot products of Y with, say, each row. Of the resulting vector you the compute the dot product again with Y.
Edit added: The length nrows of the nested loops in the code should be determined from the length of the vector y, perhaps with a check that the length of x is nrows*nrows.
I have a vector,"a", and a filter,"b".Both of those vectors contain only 0 or 1.
I would like to transform "a" such that any sequence of 1 only starts when b is at 1.
I have illustrated this using a loop but, as my vectors are huge, it is extremely inefficient.
The result I would like is stored in "r".
a=[0;0;1;1;1;1;1;1;0;0;1;1;0;0;1;1;1;1;1];
b=[0;0;0;0;1;0;1;0;0;1;0;1;0;1;1;0;0;0;0];
r=[0;0;0;0;1;1;1;1;0;0;0;1;0;0;1;1;1;1;1];
for i=2:length(a)
if a(i)==1 &&a(i-1)==0 && b(i)==0
a(i)=a(i-1);
end
end
assert(sum(a==r)==length(a))
Here's a two-liner:
r = a;
r([false; diff(a)>0 & b(2:end)==0]) = 0;
Please note that you need to adapt the code for row vectors (this works for column vectors).
Say I have two lists:
M=(0,1,2,3) and N=(0,2,4,6)
And I wish to put into a list all the combinations of Mi,Mj,Ns,Nt (where i,j,s,t are subscripts so for i=1 M=0, i=2 M=1 etc.) such that:
C = a^(Mi+Mj) + b^(Ns+Nj)
First in the list would be
C = a^(0+0) + b^(0+0)
C = a^(1+0) + b^(0+0)
C = a^(1+0) + b^(2+0)
Is there a neater way of writing this out than using the 'for' clause 4 times?
for i from 1 to 4 do
for j from 1 to 4 do
for s from 1 to 4 do
for t from 1 to 4 do
C = a^(Mi+Mj) + b^(Ns+Nj)
end do;
end do;
end do;
end do;
I will be putting it into an array, but I want to limit the recursion because maple doesn't like it! Is it possible to put this into a 2x2 array with 4 variables?
I considered making 2 lists of all the combinations of Mi+Mj and all the combinations of Ns+Nt then putting those together in an array, but it comes out similar to what I want, yet not quite right.
I do not use Maple, but after a quick Google search, it turns out that Maple at least supports nested loops. So....
First, iterate through all the combinations of M, calculate a^(Mi + Mj), and store the results in A.
for i from 1 to 4 do
for j from 1 to 4 do
A = a^(Mi+Mj)
end do;
end do;
Second, do the same for N, and store the results in B.
Third, get C.
for i from 1 to 16 do
for j from 1 to 16 do
C = Ai + Bj
end do;
end do;
Actually, the original approach requires a lot of redundant calculations, and the above approach eliminates the redundancy. Thus, I guess it is not only workable but also faster.