Macro numeric values comparing - macros

Question

I am trying to compare two numberic value in a Macro.
But I keep getting the following message:
ERROR: A character operand was found in the %EVAL function or %IF condition where a numeric operand is required. The condition was: 0.2
ERROR: The %TO value of the %DO I loop is invalid.
ERROR: A character operand was found in the %EVAL function or %IF condition where a numeric operand is required. The condition was: 0.05
ERROR: The %BY value of the %DO I loop is invalid.
ERROR: The macro FAIL will stop executing.
My code is the following:
%macro fail;
%do i=0 %to 0.2 %by 0.05;
data failcrs;
set fail;
if f_p>=input(&i, 8.) then output;
run;
%end;
%mend failcrs;
f_p is a numeric variable.
What is wrong with my code? Please help.
Thank you so much!

Answer 1

Conditional tests in macro code (%if, %until, %while, etc) use %eval() macro function that only does integer arithmetic. This includes the increments and tests done in a %do-%to-%by loop.
To use floating point arithmetic you need to use the %sysvalf() macro function.
You could code your own increments to the loop counter.
%let i=0;
%do %while( %sysevalf( &I <= 0.2 ) );
...
%let i=%sysevalf(&i + 0.05);
%end;
Or make the loop counter an integer and use another macro variable to hold the fraction.
%do j=0 %to 20 %by 5 ;
%let i=%sysevalf(&j/100);
...
%end;

Answer 2

You have a couple of issues.
Macro loops work better with integers, but an easy workaround is a %DO %UNTIL loop instead.
Name on %MEND is different than on %MACRO
Invalid values for %DO %I loop.
Non-unique data set name, which means the output overwrites itself.
*fake data to work with;
data fail;
do f_p=0 to 0.2 by 0.01;
output;
end;
run;
%macro fail;
%let i=0;
%do %until(&i = 0.2); /*2*/
data failcrs_%sysevalf(&i*100); /*3*/
set fail;
if f_p>=&i then output;
run;
%let i = %sysevalf(&i + 0.05);
%end;
%mend fail; /*3*/
*test macro;
%fail;
The numbers in the comments align with the issues identified.

Answer 3

Try using best32. But why do you want to loop, when your dataset is overwritten for each loop. Please check log for each of step below. As at #Reeza in comments explains below you even do not an input statement
Options mprint;
/* do this*/
%macro fail;
%let i =15;
data failcrs;
set sashelp.class;
if age lt input(&i, best32.) then output;
run;
%mend fail;
%fail
/* dataset overwritten every time to finally pick up 15 as value check in the log*/
%macro fail1;
%do i = 1 %to 15;
data failcrs1;
set sashelp.class;
if age lt input(i, best32.) then output;
run;
%end;
%mend fail1;
%fail1

Answer 4

%macro fail;
%let i=0;
%do %until(&i = 0.2);
data failcrs;
set crse_grade_dist_fail;
if f_p>=&i then output;
run;
proc sql;
create table count_failclass as
select strm, count(class_nbr) as numfclass_%sysevalf(&i*100)
from failcrs
group by strm;
quit;
proc sql;
create table failfaculty as
select strm, instructor_id, instructor, count(class_nbr) as numfclass
from failcrs
group by strm, instructor_id, instructor;
quit;
proc sql;
create table count_failfaculty as
select strm, count(instructor) as numffaculty_%sysevalf(&i*100)
from failfaculty
group by strm;
quit;
data count_class_faculty;
set count_class_faculty;
set count_failclass;
set count_failfaculty;
run;
%let i = %sysevalf(&i + 0.05);
%end;
%mend fail;
Good thing is my data doesn't have f_p=0, all of them is greater than zero. Because I only want to count failed courses.

Answer 5

Documentation is written to be read, a simple search for "SAS 9.4 Macro Do" should explain it all -- start, stop and by are integers -- integers in the sense that whatever macro source expression in their place evaluates implicitly or explicitly to an integer at need time.
The macro you coded is a little strange. It will generate multiple data steps that all overwrite the same dataset. You might want to concentrate on not writing macro code first, and move to it when the need to have repetitive boilerplate code submitted. Writing good macro code means you have to think in terms of "will this generate appropriate source code and what side effect will these macro statements have in their resolution scope"
%DO, Iterative Statement
Syntax
%DO macro-variable=start %TO stop <%BY increment>;
  text and macro language statements
%END;
Required Arguments
macro-variable
names a macro variable or a text expression that generates a macro
variable name. Its value functions as an index that determines the
number of times the %DO loop iterates. If the macro variable specified
as the index does not exist, the macro processor creates it in the
local symbol table.
You can change the value of the
index variable during processing. For example, using conditional
processing to set the value of the index variable beyond the stop
value when a certain condition is met ends processing of the loop.
startstop
specify integers or macro expressions that generate integers
to control the number of times the portion of the macro between the
iterative %DO and %END statements is processed.
The first time the
%DO group iterates, macro-variable is equal to start. As processing
continues, the value of macro-variable changes by the value of
increment until the value of macro-variable is outside the range of
integers included by start and stop.
increment
specifies an integer
(other than 0) or a macro expression that generates an integer to be
added to the value of the index variable in each iteration of the
loop. By default, increment is 1. Increment is evaluated before the
first iteration of the loop. Therefore, you cannot change it as the
loop iterates.