Sas-training-in-mumbai

*Built-in functions
*Data manipulation
*Updated often to include new applications
*Different packages complete certain tasks
more easily than others
*Packages we will introduce
*SAS
*R (S-plus)

*Easy to input and output data sets
*Preferred for data manipulation
*“proc” used to complete analyses with built-in
functions
*Macros used to build your own functions

*SAS Structure
*Efficient SAS Code for Large Files
*SAS Macro Facility

*Missing semicolon
*Misspelling
*Unmatched quotes/comments
*Mixed proc and data statement
*Using wrong options

*Data Step: input, create, manipulate or output
data
*Always start with a data line
*Ex. data one;
*Procedure Step: complete an operation on data
*Always start with a proc line
*Ex. proc contents;

*System options are global instructions that
affect the entire SAS session and control the
way SAS performs operations. SAS system
options differ from SAS data set options and
statement options in that once you invoke a
system option, it remains in effect for all
subsequent data and proc steps in a SAS job,
unless you specify them.
*In order to view which options are available and
in effect for your SAS session, use proc options;
run;

* center controls whether SAS procedure output is centered. By default, output is
centered. To specify not centered, use nocenter.
* date prints the date and time to the log and output window. By default, the date and
time is printed. To suppress the printing of the date, use nodate.
* label allows SAS procedures to use labels with variables. By default, labels are
permitted. To suppress the printing of labels, use nolabel.
* notes controls whether notes are printed to the SAS log. By default, notes are printed.
To suppress the printing of notes, use nonotes.
* number controls whether page numbers are printed. By default, page numbers are
printed. To suppress the printing of page numbers, use nonumber.
* linesize= specifies the line size (printer line width) for the SAS log and the SAS
procedure output file used by the data step and procedures.
* pagesize= specifies # of lines that can be printed per page of SAS output.
* missing= specifies the character to be printed for missing numeric values.
* formchar= specifies the the list of graphics characters that define table boundaries.
Example:
OPTIONS NOCENTER NODATE NONOTES LINESIZE=80 MISSING=. ;

SAS data set control options specify how SAS data
sets are input, processed, and output.
*firstobs= causes SAS to begin reading at a specified observation in a
data set. The default is firstobs=1.
*obs= specifies the last observation from a data set or the last
record from a raw data file that SAS is to read. To return to using
all observations in a data set use obs=all
*replace specifies whether permanently stored SAS data sets are to
be replaced. By default, the SAS system will over-write existing SAS
data sets if the SAS data set is re-specified in a data step. To
suppress this option, use noreplace.
Example:
*OPTIONS OBS=100 NOREPLACE;

Error handling options specify how the SAS System
reports on and recovers from error conditions.
* errors= controls the maximum number of observations for which
complete error messages are printed. The default maximum number
of complete error messages is errors=20
* fmterr controls whether the SAS System generates an error message
when the system cannot find a format to associate with a variable.
SAS will generate an ERROR message for every unknown format it
encounters and will terminate the SAS job without running any
following data and proc steps. To read a SAS system data set without
requiring a SAS format library, use nofmterr.
Example:
OPTIONS ERRORS=100 NOFMTERR;

*data statement names the data set you are
making
*Can use any of the following commands to
input data
*infile Identifies an external raw data file to read
with an INPUT statement
*input Lists variable names in the input file
*cards Indicates internal data
*set Reads a SAS data set

*To look at the variables in a data set, use
*proc contents data=dataset;
run;
*To look at the actual data in the data set,
*proc print data=dataset (obs=num);
var varlist;
run;

data treat;
infile “g:sharedBIO271treat.dat”;
input id bpa bpb chola cholb;
run;
proc print data = treat (obs=10);
run;
proc contents data=treat;
run;

*blank space (default)
*DELIMITER= option specifies that the INPUT
statement use a character other than a blank
as a delimiter for data values that are read
with list input

Sometimes you want to input the data yourself
Try the following data step:
data nums;
infile datalines dsd delimiter=‘&';
input X Y Z;
datalines;
1&2&3
4&5&6
7&8&9 ;
Notice that there are no semicolons until the
end of the datalines

*Another way to input data using the
keyboard (and often a last resort if having
problems input the data) is cards
*Similar to datalines
*data score;
input test1 test2 test3;
cards;
91 87 95
97 . 92
. 89 99
;
run;

*Sometimes your data will have characters
*Example:
data fam;
input name$ age;
cards;
Brian 27
Andrew 29
Kate 24
run;
proc print data=fam;
run;
*What is different and what happens if you
don’t have the dollar sign?

*The final way we will show to input data is if
you have a SAS data set , you can use a
libname command
libname summer "g:sharedbio271";
data treat2;
set summer.treat2;
run;
*Look at the data set with proc print

Variable label: Use the label statement in the data step
to assign labels to the variables. You could also assign
labels to variables in proc steps, but then the labels only
exist for that step. When labels are assigned in the data
step they are available for all procedures that use that
data set.
Example:
DATA labtreat;
SET treat;
LABEL id=“patient id” bpa =“BP on treatment A" bpb =“BP on treatment B"
cholA=“Cholesterol on treatment A” cholB=“Cholesterol on treatment B";
RUN;
PROC CONTENTS DATA=labtreat;
RUN;

*Make a data set with the following data calling
it redsox
*8, 58, 491, 163
7, 50, 469, 133
31, 107, 458, 136
33, 111, 410, 117
*Label the variables HR, RBI, AB, HITS
*Use proc print to ensure that you have input
the data correctly

*One of the best parts of SAS is the ability to complete data
manipulations
*There are four major types of manipulations
*Subset of data
*Drop / keep variables
*Drop observations
*Concatenate data files
*Merge data files
*Create new variables

*SAS easily allows you to make a data set
with a subset of the variables
*What do you think happens with this code?
DATA redsox2;
SET redsox;
KEEP ba rbi;
RUN;
*How do you think you could use drop to do
the same thing?

*We can also get a subset of the observations
*Read in treat2 from the g: drive
*This is helpful when we want to remove
missing data
DATA notreat2;
SET treat2;
IF cholA ^= . ;
RUN;

*SAS allows us to combine dataset by adding
more observations, using
data tottreat;
set treat treat2;
run;
*Check that it worked using proc print
*If a variable is called by a different name in
each dataset, you must use:
data momdad;
set dads(RENAME=(dadinc=inc)) moms(RENAME=(mominc=inc));
run;

*SAS also allows us to add more variables by merging
data files
*The data set demo gives demographic information
about the patients in treat
*Read in demo
*Now, use this code to combine the information
data extratreat;
merge treat demo;
by id;
run;
*Note: the data in each data set must be sorted to
use this code

*We can make new variables in a data step
*Let’s make a new variable in the redsox data set by
finding batting average and a variable for hr30
data redsox2;
set redsox;
ba=hits/ab;
if hr>=30 then hr30=1 else hr30=0;
run;

*Make a new data set called redsox3 using the
following data and combine it with redsox
7, 51, 378, 113
4, 41, 367, 99
20, 58, 361, 109
*Make a new variable in redsox3 that equals 1 if
rbi is more than 100 and 0 if rib is less than or
equal to 100

*file: Specifies the current output file for PUT
statements
*put: Writes lines to the SAS log, to the SAS
procedure output file, or to an external file
that is specified in the most recent FILE
statement.
Example:
data _null_;
set redsox;
file ‘p:redsox.csv' delimiter=',' dsd;
put hr rbi ab hits;
run;

*The INFILE statement specifies the input file for
any INPUT statements in the DATA step. The FILE
statement specifies the output file for any PUT
statements in the DATA step.
*Both the FILE and INFILE statements allow you to
use options that provide SAS with additional
information about the external file being used.
*An INFILE statement usually identifies data from an
external file. A DATALINES statement indicates that
data follow in the job stream. You can use the
INFILE statement with the file specification
DATALINES to take advantage of certain data-
reading options that effect how the INPUT
statement reads in-stream data.

*Missing values in SAS are shown by .
*As a general rule, SAS procedures that perform
computations handle missing data by omitting
the missing values, including proc means, proc
freq, proc corr, and proc reg
*Check SAS web page for more information

* SAS treats a missing value as the smallest
possible value (e.g., negative infinity) in
logical statements.
data times6;
set times ;
if (var1 <= 1.5) then varc1 = 0; else varc1 = 1 ;
run ;
Output:
Obs id var1 varc1
1 1 1.5 0
2 2 . 0
3 3 2.1 1

*proc print and proc contents- we have seen
these
*proc sort
*proc means
*proc univariate
*proc plot

*var: lists the variables you want to perform the
proc on
*by: breaks the data into groups
*where: limits the data set to a specific group
of observations
*output: allows you to output the results into a
data set

*We can use proc sort to sort data
*The code to complete this is
proc sort data=extratreat ; by gender ; run ;
proc sort data=extratreat out=extreat ; by gender ; run ;
proc sort data=extratreat out=extreat2; by descending
gender ; run ;
proc sort data=extratreat out=extreat3 noduplicates;
by gender ; run ;

*The basic form of proc means is
*proc means data=extratreat;
var ______;
by _______;
where _______;
output out=stat mean=bpamean cholamean;
run;
*The basic form of proc univariate is the
same, but much more information is given
*It is helpful to use the output window to
get the info you need

*To make different plots in SAS, you use
proc plot
*Scatterplot
*proc plot data=redsox;
plot rbi*ab;
run;
*You can also make plots using
*proc univariate data=redsox plot;
var rbi;
run;

*Find the mean blood pressure on treatment A
in women
*Make a scatterplot of blood pressure on
treatment B versus blood pressure on
treatment A in men
*Find the median number of home runs hit by
the Red Sox

Macros are the SAS method of making functions
*Avoid repetitious SAS code
*Create generalizable and flexible SAS code
*Pass information from one part of a SAS job to
another
*Conditionally execute data steps and PROCs

*SAS macro variable
*SAS Macro
*There are many discussions of macro variables
on the web; one good one is given here:
http://www2.sas.com/proceedings/sugi30/130
-30.pdf

Two delimiters will trigger the macro
processor in a SAS program.
*&macro-variable
This refers to a macro variable. The current
value of the variable will replace &macro-variable;
*%macro-name
This refers to a macro, which consists of one or
more complete SAS statements, or even whole data
or proc steps.

*SAS Macro variables can be defined and used
anywhere in a SAS program, except in data
lines. They are independent of a SAS dataset.

%LET: assign text to a macro variable;
%LET macrovar = value
1. Macrovar is the name of a global macro variable;
2. Value is macro variable value, which is a character
string without quotation or macro expression.
%PUT: display macro variable values as text
in the SAS log; %put _all_, %put _user_
&macrovar: Substitute the value of a macro
variable in a program;

*Here is an example of how to use a macro variable:
*%let int=treat;
proc means data=∫
run;
*Now we can rerun the code again simply changing the
value of the macro variable, without altering the rest
of the code.
*%let int=redsox;
proc means data=∫
run;
*This is extremely helpful when you have a large
amount of code you want to reference

*Definition:
%MACRO macro-name (parm1, parm2,…parmk);
Macro definition (&parm1,&parm2,…&parmk)
%MEND macro-name;
*Application:
%macro-name(values of parm1, parm2,…,parmk);

Import Excel to SAS Datasets by a Macro
%macro excelsas(in, out);
proc import out=work.&out
datafile=“g:sharedbio271&in"
dbms=excel replace;
getnames=yes; run;
%mend excelsas;
% excelsas(practice.xls,test)
Use proc print to ensure that you have the data
input properly

%let int=treat;
%let dop=%str(id bpa);
%macro happy;
data new;
set ∫
drop &dop;
run;
proc means data=new;
run;
%mend happy;
%happy

Sas-training-in-mumbai

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