Sas Basicsppt

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SAS Overview

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` Data Portion

` Rules for SAS name (Varibale/Data Set)


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` Observation flow via Data step


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` Program data vector (PDV) is a logical area in memory where SAS builds a data set, oneobservation at a time. When a program executes, SAS reads data values from the input buffer (alogical area in memory into which SAS reads each record of raw data when SAS executes anINPUT statement) or creates them by executing SAS language statements. The data values areassigned to the appropriate variables in the program data vector. From here, SAS writes the valuesto a SAS data set as a single observation. When the DATA step reads a SAS data set, SAS readsthe data directly into the program data vector.

1. The SAS automatic variables ( _N_ and _ERROR_ )

2. Temp variable (First., Last. , IN , END etc)

While reading a Raw data file:-

` Compilation Phase - It checks for syntax errors and conversion of data step into the machine codealong with creation of two things viz. INPUT BUFFER and PDV.

`

Execution Phase - Before beginning of the this phase all the variables will be initialized tomissing(if character) and periods(if numeric)[use "put _all_" statement to check PDV status in thelog]. Then when the input statement is encountered for the first time the first record from raw datafile is moved from it to INPUT BUFFER after that one observation is then again moved to PDV.When run statement is encountered, then the implicit OUTPUT statement forces the read data rowto the output data set.

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` Sample programe

Data Total_points (drop=TeamName); 1

input TeamName $ ParticipantName $ Event1 Event2 Event3; 2

TeamTotal + (Event1 + Event2 + Event3); 3

datalines;

Knights Sue 6 8 8

Kings Jane 9 7 8Knights John 7 7 7

;

Run;

` Values from the First Record are Read (Input buffer, PDV, Output)

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Computed Value of the Sum Statement

http://support.sas.com/documentation/cdl/en/lrcon/62955/HTML/default/viewer.htm#a000961108.htm


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` Parts of a Program

Introduction comments

Data import

Data manipulation/cleaning

Data analysis

Data export

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` Semi-colon at the end of every statement

` Spacing for aesthetics, not syntax

` Comments

/* Comment */

* Comment ;

*/; - completes open comments from prior runs

` Run; at the end to execute the code

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` OPTIONS statement

Specifies SAS system options

Often used at the beginning of a program to specify

page formatting, limit the number of observationsprocessed, etc.

Unless re-specified, options stay the samethroughout the entire SAS session for all DATA stepsand PROCs that execute (even if the currentprogram does not specify them).

OPTIONNOPRINT MLOGIC SYMBOLGENpagesize=60 ;

DM LOG 'CLEAR' LOG;

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` A Libname is a reference to a directory.

libname test c:\temp\;

Must be used for a permanent SAS data set

` A Fileref is a reference to a specific file. filename flatfile c:\temp\test.txt;

Provides an easy way to change the file used whentesting

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` % Let allows you to create substitution for namesthroughout the data set

Use % Let when high chance that it will change

Allows user to make changes in one place, rather

than throughout the program

Often use % Let for path names and file names

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` Example of a %Let statement

%LET OUTPUTPATH=C:\Documents and Settings\MyDocuments\SAS99 v3\Testing v3\Output;

Filename PROGFILE "&OUTPUTPATH.\PROGFILE.sas";Filename EXCLUDE "&OUTPUTPATH.\EXCLUDE.sas";

Filename OUT_ENT "&OUTPUTPATH.\Entry_nonzero.xls";

Filename OUT_DQ "&OUTPUTPATH.\Mat_Exceptions.xls";

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Importing Data into SAS

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` SAS can import the following types of files:

Text (fixed-length, variable-length and delimited)

Excel workbooks

Access databases

DBF files

EBCIDIC files (IBM Mainframe)

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SAS File Transfer.sas


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` There are two types of data sets:

Working

x Temporary data set stored in the Work directory

x Once SAS is closed, the data sets are deleted

Permanent

x Data sets stored in folder on computer

x Use libname reference as a pipeline to point to

permanent SAS datasets for programx If SAS is closed, data sets are saved on the

computer

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` SAS views dates as the number of days sinceJanuary 1, 1960.

` Since SAS considers dates to be numeric,

calculations are easily performed.

` SAS reads and prints a wide variety of datesincluding mm/dd/yy, yyyymmdd, Julian, etc..

` YEARCUTOFF= system optionhttp://ftp.sas.com/service/techsup/tsnews-l/0040.html

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` When raw data contains invalid dates (e.g. 000000),dates can be read in as character and then convertedto a date format to eliminate errors in the log. Forexample,

IF DATEVAR1 NE '000000' THEN DATEVAR =INPUT(DATEVAR1,YYMMDD6.);

` Comparisons to SAS date constants

IF date > 12312000; WRONG!

IF date > 31dec2000d; RIGHT!

` SAS Date Functions

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` Informat Tells SAS how to

read data valuesinto a variable

Used in inputstatements

` Format

Tells SAS how towrite data valueseither to a file, areport, or a screen

Used in outputstatements

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DATA TEMP;INFILE "G:\Mydocument\GLDET.TXT" DELIMITER = '~'

MISSOVER DSD LRECL=32767 FIRSTOBS=2 ;

INFORMAT GL_ACCOUNT__ $33. ;

INFORMAT GL_ACCOUNT_DESCRIPTION $128. ;

INFORMAT ACCOUNT_TYPE_INDICATOR $1. ;

INFORMAT FDC_CODE $10. ;

FORMAT GL_ACCOUNT__ $33. ;FORMAT GL_ACCOUNT_DESCRIPTION $128. ;

FORMAT ACCOUNT_TYPE_INDICATOR $1. ;

FORMAT FDC_CODE $10. ;

INPUT

GL_ACCOUNT__ $

GL_ACCOUNT_DESCRIPTION $

ACCOUNT_TYPE_INDICATOR $

FDC_CODE $

;

RUN;


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Data Analysis

and Manipulation

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` Once SAS imports the data, there are two types ofstatements for manipulation and analysis:

Data Step

x If-Then-Else statements

x Mergesx Loops

Proc Step

x

SAS-defined procedures for analysis (summaries,statistics, etc.)

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` DATA steps in SAS are used to:

Read in raw data files

x Use INPUT statement

Read in and manipulate SAS data sets

x Use SETor MERGEstatements

x Subset data

x Create additional fields

x Perform calculations

x Merge SAS data sets

x Append SAS data setsx Loop through SAS data sets

x etc.

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` The DROP= option eliminates the specified variables fromthe output data set. For example, DATA newdata1(DROP=field1 field2);

` The KEEP= option keeps only the specified variables in the

output data set. For example, DATA newdata2(KEEP=field3 field4);

` The RENAME= option renames variables in the output dataset. This is commonly used for merges. For example,

DATA new(REN

AME=(oldname=newname));

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` Example of a Data Step

data rev_chart (keep = acct_type rev_debit_amt rev_debit_ct rev_credit_amtrev_credit_ct

exp_debit_amt exp_debit_ct exp_credit_amt exp_credit_ct period);set input_data year_input_data;if Acct_Type = 'Revenue' then do;

rev_debit_amt = debit_amt;rev_debit_ct = debit_cnt;rev_credit_amt = credit_amt;rev_credit_ct = credit_cnt;

end;else if Acct_Type = 'Expense' then do;

exp_debit_amt = debit_amt;exp_debit_ct = debit_cnt;

exp_credit_amt = credit_amt;exp_credit_ct = credit_cnt;

end;else delete;run;

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` If-Then-Else Statements Simple logic in order to perform data manipulation

data data1;set libname1.perm_data1;IF day_of_Week = "MON" THEN ID = 2; ELSE

IF day_of_Week = "TUE" THEN ID = 3; ELSEIF day_of_Week = "WED" THEN ID = 4; ELSEIF day_of_Week = "THU" THEN ID = 5; ELSEIF day_of_Week = "FRI" THEN ID = 6; ELSEIF day_of_Week = "SAT" THEN ID = 7; ELSEIF day_of_Week = "SUN" THEN ID = 1; ELSEIF day_of_Week = "HOL" THEN ID = 8;

run;

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` Use If-Then-Else statements to subset your data

Use If condition to keep records with condition

Break up data set into several data sets by condition

` Example of SAS code to subset data:

DATA excep(RENAME=(sumfield=excepamt)gooddata(DROP=field1 field2);

SET origdata;

sumfield = field1 + field2;

IF sumfield GT 100 THENOUTPUT excep;ELSEOUTPUT gooddata;

RUN;

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` If there are several steps in an If-Then-Else statement, use a Then Do orElse Do

Use End statement at end of Do statement

` Example of code:

DATA DATAKEEP DATAEXCLUDE;SET DATA1;IF VAR1="KEEP" THEN DO;

DATASET="DATAKEEP";

OUTPUT DATAKEEP;

END;ELSE DO;

DATASET="DATAEXCLUDE";

OUTPUT DATAEXCLUDE;

END;RUN;

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` Blanks and Null Values

There are several ways to flag blank / null records:

x charvar = ;

x numvar = .;

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` A SAS merge combines records that have equalvalues based on the field(s) in the BYstatement.

` The data sets must be sorted by the field(s) in theBYstatement prior to performing the merge.

`

The IF statement will select the records to includein the resulting table.

` Many to many merges will not have the same resultas a many to many join.

` Overlaying of common variables will occur (Update

will be helpful) Use PROC CONTENTS and RENAME= data setoption

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SAS Dataset 1

CodeIn2

A 1A 1

B 1

C 1

D 1F 1

SAS Dataset 4

CodeAmt

A 9

B 1

C .

E 2

F .

3

1

SAS Dataset 2

CodeAmt

A 1

B .

C 2

D 5

F 3

SAS Dataset 2

CodeIn1

A 1

C 1

C 1

E 1

F 1

F 1


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Merge SAS Data Set1-2

CodeIn2 In1A 1 1A 1 1

B 1 0C 1 1C 1 1D 1 0E 0 1

F 1 1F 1 1

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Example SAS MERGE.SAS

Merge SAS Data Set3-4

Code AmtA 9B 1C .D 5E 2F .

Update SAS Data Set3-4

Code Amt

A 9B 1C 2D 5E 2F 3


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` Example of Merge in Data step:

data data_merge notina notinb;

merge data1 (in=a) data2 (in=b);

by field1 field2 field3;if a and b then output data_merge;

else if a and not b then output notinb;

else if not a and b then output noina;

run;

http://support.sas.com/techsup/technote/ts705.pdf

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` Loops allow the users to iterate through a variable or data step ina controlled manner

` Two types of loops in SAS Do Until Do While

` Must use an END statement

` Example of Do Loop code:

DATA newfile;SET oldfile;

DO WHILE (condition);task to perform during condition;

END;RUN;

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` CAT, CATS,CATT,CATX

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` Count

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` Countc

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` Ifc

ifc (condition, value #1, value #2, value #3)

looks at a condition and returns user specified, character values if the condition is true, false, orresults in a missing value.

Parameters: condition (numeric expression)

value #1: char expression if condition is true.

value #2: char expression if condition is false.

value #3: char expression if condition results in a missing value.

` Ifn

ifn (condition, value #1, value #2, value #3)

looks at a condition and returns user specified, numeric values if the condition is true, false, orresults in a missing value.

Parameters:

condition (numeric expression)

value #1: num expression if condition is true.

value #2: num expression if condition is false.

value #3: num expression if condition results in a missing value.

` ifn comparison to if/then/else

com= ifn(sales >= quota, sales* mqpct , sales* nmqpct );

is the same as:

if sales >= quota then

com=sales* mqpct

` else

com=sales* nmqpct );

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ifc.txt


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` lengthc, lengthm, lengthn

Differences:

lengthc: returns the length of a string including trailing blanks.

lengthm: returns the length of the variable allocated in memory.

lengthn: returns the length of a string excluding the trailing blanks.

1. returns 0 if a string is blank, compared to the length function whichreturns 1.

` subpad

parameters:

-string string to take an excerpt (substring) from.

-position location of first character in the substring.

-length the number of characters in the subpad WILL return a variable with the length specified, padding the resultswith spaces.

subpad can return a string with a length of zero.

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` substrn

parameters:

-string string to take an excerpt (substring) from.

-position - location of first character in the substring.

-length - the number of characters in the

same as the substr function except:

substrn truncates the result when length exceeds the length of the string.

there will be no error messages for invalid third arguments.

` ANYALNUM (variable)beats using: indexc(lowcase(variable),qwertyuiopasdfghjklzxcvbnm1234567890)

` ANYALPHA (variable)

beats using: indexc(lowcase(variable),qwertyuiopasdfghjklzxcvbnm)

` NOTALNUM (variable)

beats using: indexc(lowcase(variable),qwertyuiopasdfghjklzxcvbnm1234567890) =0

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substr.txt


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` Proc statements are SAS procedures for dataanalysis

Proc Contents

Proc Datasets

Proc Means Proc Summary

Proc Freq

Proc Format

Proc Univariate Proc Print

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` Provides field information and data set information

Field Info: Name, Type, Format, Label

Data Set Info: Creation date, Number of observations

Automatically prints to output

Very useful to perform prior to a merge to ensurevariables from one data set will not write over variablesfrom the other data set.

` Example of code:

PROC CONTENTS DATA=dataset;

RUN;

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` Provides information regarding a library, including datasets in thelibrary

Can perform the following:

x Append datasets together

x Copy datasets to other libraries

x Delete datasets

x Modify the contents of a dataset

x Rename a dataset

` Example of code:

PROC DATASETS LIBRARY=libname;

RUN;

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Proc dataset.txt


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` Computes descriptive statistics on numeric variables in a SASdata set. Results can be output to a new SAS data set. Defaults to print all descriptive statistics (e.g. mean, standard

deviation, minimum, etc.) Output automatically prints If no numeric variables are specified in the VAR statement, then

all numeric variables in the data set are analyzed

` Example of code:

PROC MEANS DATA=oldfile;CLASS division dept;

VAR units value;

RUN;

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` Computes descriptive statistics on numeric variables in a SASdata set and outputs the results into a new SAS data set

Descriptive statistics must be specified in the OUTPUTstatement

Output does not automatically print

If no numeric variables are specified in the VAR statement, then

a simple count of the observations is generated.

` Example of Code:

PROC SUMMARY DATA=oldfile NWAY;

CLASS division dept;

VAR units value;

OUTPUT OUT=currfile SUM=;

RUN;

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` Produces 1-way to n-way frequency and cross-tabulationtables

` Example of Code:

PRO

C FREQ DATA=dataset

NOPRI

NT;TABLES variable / LIST MISSINGOUT=datanew;

RUN;

DATA datanew2;SET datanew;

IF COUNT > 1 THENOUTPUT datanew2;RUN;

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` PROC FORMAT, because of its name, is most often used tochange the appearance of data for presentation.

` Example of Code:Proc format;value tempfmt low -< 61 = ' 1'

61 -< 63 = ' 2'63 - high = ' 3'other = ' ';run;data pme;set pme;tempcode=put(avgtemp, tempfmt.);Run;http://www2.sas.com/proceedings/sugi30/001-30.pdf

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Proc format.txt


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` Provides statistics on numeric variables

Automatically prints the results to output

` From the report:

Number of missing observations

Number of records > 0, = 0, and


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` Print data set to screen Less frequently used if using PC SAS However, when using SAS on the Mainframe, Proc

Print would allow you to see your data

*SET EXTERNAL LOG;

PROC PRINTTO

PRINT = "&PATH.\PROGRAMS\&CLIENT. &PERIOD. &PROGRAM..DOC"

LOG = "&PATH.\PROGRAMS\&CLIENT. &PERIOD. &PROGRAM..DOC

NEW;

RUN;

http://support.sas.com/documentation/cdl/en/proc/61895/HTML/default/viewer.htm#a000146809.htm

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` What is a macro?

A macro is a block of code meant for repetitiveruns through the data

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` Example of macro code:

%MACRO Macro_name(DATASET);

DATA &DATASET.;

SET &DATASET.;

IF Var1=. THEN Var1=0;

RUN;

%MEND Macro_name;

%Macro_name(TOTAL);

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SAS Output

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` There are several ways you can export data:

Proc Export

ODS (Output Delivery System)

DDE (Data Dynamic Exchange)

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` Proc Export is the mostcommon way to export data

` Very similar to the ProcImport step, but works in

the reverse` SAS can export to the

following files:

Excel

Access

DBF Text

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Example

SAS Program appended

at #17


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DOC File

Inven ory Data for SAS Basi s.txt

Input Data

SAS Basi s Exer ise1 Solution.sas

Input Data

Exercise1 Exercise2

DOC File

AR Inventory for SAS Training.txt AR Data SAS Training.txt

SAS Basi s Exer ise2 Solution.sas


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Debugging and Checking SAS

Programs

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` It is essential to check your SAS log for errors:

Error (in red): Very Bad!

Warning (in green): Maybe bad!

` SAS will not stop its processing if it finds errors!

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` Lets run Debug Program.sas to see different types oferrors.

` Things to look out for: Colors or perform search for error and warning

Dropped records or observations

` Visualize and understand how your results shouldlook. Did the results turn out as planned?

5858

Use inventory raw file appended on slide #50SAS Basics ebug Program.sas


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` proc SQL

` Macros

` Proc Tabulate/Report

` Merge using Proc format

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