I would like to set the length of an array depending on what value i obtain from reading a dataset:number which has one variable num with one numeric value. But I am getting an error message: saying that I cannot initiate the probs array. Can i get any suggestion on how to solve this issue? (I really don't want to hardcode the length of the probs array)
data test;
if _n_=1 then do;
set work.number;
i = num +1;
end;
array probs{i} _temporary_ .....
SAS Data step arrays can not be dynamically sized during step run-time.
One common approach is to place the computed number of rows of the data set into a macro variable before the data step.
I'm not sure what you are doing with probs.
What values will be going into the array elements ?
Do you need all prob data while iterating through each row of the data set ?
Is a single result computed from the probs data ?
Example - Compute row count in a data null using nobs set option:
data _null_;
if 0 then set work.number nobs=row_count;
call symputx ('ROW_COUNT', row_count);
stop;
run;
data test;
array probs (&ROW_COUNT.) _temporary_;
* something with probs[index] ;
* maybe fill it ?
do index = 1 by 1 until (last_row);
set work.number;
probs[index] = prob; * prob from ith row;
end;
* do some computation that a procedure isn't able to;
…
result_over_all_data = my_magic; * one result row from processing all prob;
output;
stop;
run;
Of course your actual use of the array will vary.
The many other ways to get row_count include dictionary.table views, sql select count(*) into and a variety of ATTRN invocations.
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 am a SAS beginner. I have an array-like piece of data in my code, which needs to be passed to a different data step much lower in the code to do computations with it. My code does something like this (computation simplified for this example):
data _null_;
call symput('numRuns', 10000);
run;
/* this is the pre-computation step, building CompressArray for later use */
data _null_;
do i = 1 to &numRuns;
value = exp(rand('NORMAL', 0.1, 0.5)));
call symput(compress('CompressArray'||i), value);
end;
run;
data reportData;
set veryLargeDataSet; /* 100K+ observations on 30+ vars */
array outputValues[10000];
do i = 1 to &numRuns;
precomputedValue = symget(compress('CompressArray'||i));
outputValues[i] = /* calculation using precomputedValue */
end;
run;
I am trying to redo this using arrays, is that possible? E.g. to store it in some global array and access it later...
Arrays in SAS only exist for the duration of the data step in which they are created. You would need to save the contents of your array in a dataset or, as you have done, in a series of macro variables.
Alternatively, you might be able to rewrite some of your code to do all of the work that uses the array within one data step. DOW-loops are quite good in this regard.
Based on the updates to your question, it sounds as though you could use a temporary array to do what you want:
data reportData;
set veryLargeDataSet; /* 100K+ observations on 30+ vars */
array outputValues[&numruns];
array precomputed[&numruns] _temporary_;
if _n_ = 1 then do i = 1 to &numruns;
if i = 1 then call streaminit(1);
precomputed[i] = exp(rand('NORMAL', &meanNorm, &stDevNorm));
end;
do i = 1 to &numRuns;
outputValues[i] = /* calculation using precomputed[i] */
end;
run;
Defining an array as _temporary_ causes the values of the array elements to be retained across iterations of the data step, so you only have to populate it once and then you can use it for the rest of the data step.
There are a lot of ways to do this, but the hash table lookup is one of the most straightforward.
%let meannorm=5;
%let stDevNorm=1;
%let numRuns=10000;
/* this is the pre-computation step, building CompressArray for later use */
data my_values;
call streaminit(7);
do i = 1 to &numRuns;
Value= rand('Normal',&meannorm., &stDevNorm.);
output;
end;
run;
data reportData;
if _n_=1 then do;
declare hash h(dataset:'my_values');
h.defineKey('i'); *the "key" you are looking up from;
h.defineData('value'); *what you want back;
h.defineDone();
call missing(of i value);
end;
set sashelp.class; /* 100K+ observations on 30+ vars */
array outputValues[10000];
do i = 1 to &numRuns;
rc=h.find();
outputValues[i] = value;
end;
run;
Basically, you need to 'load' the table in some fashion and do [something] with it. Here's one easy way.
In your particular example there's another pretty simple way: bring it in an as array.
In this case we don't put 10k rows out, but 10k variables - then declare it as an array (again) in the new data step. (Arrays are, as noted by user667489, transient; they're not stored on the dataset in any way, except as the underlying variables, so they have to be re-declared each data step.)
%let meannorm=5;
%let stDevNorm=1;
%let numRuns=10000;
/* this is the pre-computation step, building CompressArray for later use */
data my_values;
call streaminit(7);
array values[&numruns.];
do i = 1 to &numRuns;
Values[i]= rand('Normal',&meannorm., &stDevNorm.);
end;
run;
data reportData;
if _n_=1 then set my_values(drop=i);
set sashelp.class; /* 100K+ observations on 30+ vars */
array outputValues[&numruns.];
array values[&numruns.]; *this comes from my_values;
do i = 1 to &numRuns;
outputValues[i] = values[i];
end;
drop values:;
run;
Here note that I have the set in if _n_=1 still - otherwise it would terminate the data step after the first iteration.
You could also use a format, as Reeza notes, or several other options - but I think these are the simplest.
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 am trying to loop through a column with 50000 rows. I would like to compare the value in say i with (i+1). The only way I know how to do this is by defining an array. However, there is only one variable i.e. The variables column name e.g. Col but 50000 observations within the column. When I use:
array Transform {50000} Col
where Transform is the name of the array and Col is the column name in my dataset, I receive a subscript error as there are too few variables i.e. Only 1 vs 50000. I have tried replacing {50000} with {50000,1} (and even {*}) so the compiler recognizes that there are 50k observations and only one column. Further I have attempted to transpose the dataset but this seems difficult as I need to add on another variable on to the dataset later which depends on the values of i and (i+1).
Is there a method to loop through the column to compare i and (i+1) using any method (not necessarily an array)? Thanks for the help :)
Example of using LAG:
data input;
infile cards;
input transform;
cards;
3
5
8
12
16
;
run;
data comp;
set input;
transform_change = transform - lag1(transform);
run;
For reversed order of rows:
data input_rownum / view=input_rownum;
set input;
rownum = _N_;
run;
proc sort data=input_rownum out=input_reversed;
by descending rownum;
run;
data comp_reverse;
set input_reversed;
transform_change = transform - lag1(transform);
run;
LAG1 means previous value of the variable. LAG2 is for pre-previous, and so on. Consult the documentation for more.
Arrays work across variables, so aren't suitable for your task here. There's a couple of options for you, given the small number of rows the easiest is probably to just join the dataset on itself, with the row number offset by one. You can then do your comparison.
data want;
merge have have (firstobs=2 rename=(col=col_plus1));
run;
If you only want to compare row i with i+1 you could use the lag function. This pulls the value from the previous row read (beware when using this with loops as not all rows will be processed in a loop)