Sql versus looking up john smiths address in the phone book and. This weeks sas tip is from michele burlew and her latest book sas hash object programming made easy. The cryptic appearance of hash table syntax belies the fact that it isnt hard to setup and provides much functionality with few statements. Whats your reason for wanting to change the sql to data step a hash lookup.
The two first objects available through this interface to a data step. Provides comprehensive information about the base sas component objects, which include the hash, hash iterator, and java objects. The common variable in the hash table is unique and is used as a key that provides very fast lookup into the internal memory table. Additionally, users from diverse fields with different requirements can adapt the examples in sas hash object programming made easy to fit their unique situations.
A censor variable is created based on the values from the component hash objects. Data variables four types of hash object structure. Beside doing merges using hash objects, i am struggling with hash objects when it comes to do a lookup within the same database. Technically, hash objects, interchangeably called hash tables in this book, are data structures that provide a way to efficiently search data. Therefore, if no assignment to a key or data variable appears in the program, sas issues a note stating that the variable is.
Find the power of hash how, why and when to use the. Creating a clinical summary table within a single data. This talk will cover advanced features of the sas hash object, including key summaries, check, ref, multikey objects, and sorting. That is, you cannot create a hash object in one data step and use it in another data step. We would like to show you a description here but the site wont allow us. Sep 01, 2012 hash objects, an efficient lookup tool in the sas data step, are objectoriented programming structures that function differently from traditional sas language statements. Download it once and read it on your kindle device, pc, phones or tablets. The call missing statement sets the value of these variables in the output dataset to missing initially. As usual, my favorite reference is the book data management solutions using sas hash table operations. Posted the hash object, recursion and documentation on sas communities library. I knew this book was written for me when i read the opening sentence, programming hash objects in sas sounds like a geeky process, and then immediately saw examples using data step merge, proc sql, and the hash object to present problems and show how the hash object fits in the solution space. Shelly goodin, author at sas blogs sas blogs sas blogs. Carpenters guide to innovative sas techniques textbook chapter 3.
A hash object is a type of array that a program accesses using keys. Download book sas hash object programming made easy pdf sas hash object programming made easy by michele m. Data management solutions using sas hash table operations. Michele is the author of several extremely helpful sas books. Ran a test with 10,000 in the format dataset and 1 million in the bigger dataset, and it ran pretty similarly. Five things you probably dont know you can do with a hash. Hashobject programming in sas malcolm macrae, aeso sean mccarthy, enmax 0.
For more information, see the remove method in sas component objects. Sas hash object programming made easy ebook, 2012 worldcat. A big advantage of working with hash objects is that sas dynamically allocates memory as it needs it. Paul dorfman and i wrote, data management solutions using sas hash table operations. Also see the blog post 5 tips to learn and understand the hash object in sas. Sas hash object programming made easy 9781607648017. Sas hash object programming made easy 1, michele m. It is a highperformance lookup table residing completely in the data step. A business intelligence case study, because we wanted to make sas programmers and users aware of the fact that hash tables can do a lot more than just table lookup. I like the options sas hash tables provide but its not a fitforall approach. Sas hash object programming made easy oreilly media. Sas provides various lookup techniques, and hash objects are among the newest, so therefore many users may not have yet used them.
Acknowledgments i had two concerns when i started writing this book. You do not have to determine the size of your hash object before you can use it. As you will see, hash objects are multipurpose data containers that can dramatically reduce processing time, even when dealing with hundreds of millions of records. Here ill some of the concepts and programming techniques about hash object. The values of the component hash objects are read into the program data vector and merged with the adsl data. To join table using hash objects there are four basic steps to follow.
For those unfamiliar with component objects such as hash tables, the book is a thorough introduction, offering clear explanations of elements associated with objectoriented programming and contrasting them to familiar sas concepts such as array processing, sorting, and matchmerging. Reference, replace method in sas component objects. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, or otherwise, without the prior written permission of the publisher, sas institute inc. However, one novel concept stands out as a breakthrough. Acknowledgments sas hash object programming made easy book. We have seen that these can be carried out in two different ways. The book is centered around a story line of doing a proof of concept about how hash objects can be used for many data management and business. If you are like most sas programmers, youve heard amazing claims regarding sas hash objects lightningfast lookups without the need to.
Michele burlews sas hash object programming made easy shows readers how to use these powerful features, which they can program to quickly look up and manage data and to conserve computing resources. Browse other questions tagged hash sas or ask your own question. Burlew hash objects, an efficient lookup tool in the sas data step, are objectoriented programming structures that function differently from traditional sas language statemen. The hash object provides an efficient method for quick data storage and data retrieval. Performance comparing sql, merge and the hash object to joinmerge sas. If youve already used hash objects some, then this book offers you some examples for techniques that you may not have tried or understood how to use. Sas hash object programming made easy kindle edition by michele m. Visit her author page to read free chapters and for additional bonus content. Using hash to access data outside of sas one of the most compelling reasons to use hash objects involves working with large data sets stored outside of sas.
Hash objects, an efficient lookup tool in the sas data step, are objectoriented programming structures that function differently from traditional sas language statements. Using the data step hash object to perform common clinical programming chores. The declare statement tells sas that the object reference h is a hash object. But did you know that it can contain other hash objects as well. After all, burlews book is the only one dedicated to sas hash object programming im aware of oct 2016. Because the examples presented vary in complexity, sas hash object programming made easy is useful to sas users of all experience levels, from novice programmer to advanced programmer.
Michele is the author of several revered userfriendly books. The hash key, which will be used to perform lookups, is defined to be date. Sas hash object programming made easy by michele m. The approach of comparing traditional processing techniques to those that use hash objects book description sounded promising to me and reminded me of howard schreiers book proc sql by example, which i had enjoyed reading. Michele burlews sas hash object programming made easy shows readers how to use these powerful features, which they can program to quickly look up and manage data and to. This book shows you how to make hash objects fit into what you already know, and it often compares the hash solution to a solution that uses sas language and. Reference, and the replacedup method in sas component objects. Using a common set of lookup keys, hash objects can be used to retrieve data, store data, merge join. This book is the most comprehensive coverage available of how to use and why to use the hash object for. One data variable simple hash object compositekey hash object multiple data variables multivariable hash object complex hash object hash object structure is defined by. Hash objects, an efficient lookup tool in the sas data step, are object oriented programming structures that function differently from traditional sas language statements. December i used an example on joining data using hash object instead of merge statement in the data step. This is a crucial concept if we want to fully understand the hash object. Hash tables are in existence since sas 9 version and are part of data step programming.
The hash table is created from a sas data set that is loaded into memory and is available for use by the data step that created it. Hash objects made their debut with sas 9 and has since gained some popularity, mainly for fast lookup tables and sortless merges. The declare statement tells the compiler that the object reference myhash is of type hash. A sas hash object of hash objects hash of hashes the sas hash object is a very flexible data structure. Sas hash objects have the prestige of being the fastest way to do searches using lookup tables provided that they can be loaded into memory limited by the available. Hash object lookup within the same database stack overflow.
This book shows you how to make hash objects fit into what you already know, and it often compares the hash solution to a solution that uses sas language and procedures, one that youre likely already familiar with applying. Acknowledgments sas hash object programming made easy. I am struggling with hash objects when it comes to do a lookup within the same database. Reference, removedup method in sas component objects. Sas 9 hash objects are also able to compute counts, for. Jul 26, 20 understanding how sas stores hash objects in memory. It can contain numeric and character data variables. This book introduces you to hash object programming and connects it to concepts you already understand. Save up to 80% by choosing the etextbook option for isbn. Michele burlews sas hash object programming made selection from sas hash object programming made easy book. This book helps more experienced programmers learn how to take advantage of hash object programming by comparing traditional processing techniques to those that use hash objects.
You can create a data set that contains the data in a specified hash object by using the output. A hash object exists only during a single data step. Be sure to take a look at the free chapter from her latest after reading this weeks tip. Was there enough material to develop a full book and was the topic of hash objects too technical to selection from sas hash object programming made easy book. Intuitively, we will not consider h1 and h2 as equal if h1 has one element and h2 has 2. Macro programming is a required skill for many sas programming jobs, and the sas advanced programming certification exam tests macro processing concepts. Using randomnumber functions and call routines in the data step is updated with information about new rngs and streams. Dec 06, 2019 provides comprehensive information about the base sas component objects, which include the hash, hash iterator, and java objects. The hash object operations, or their combination thereof, lend themselves to diverse sas programming functionalities well beyond the original focus on data search and retrieval.
Hash object programming is a feature in many programming languages. Using a common set of lookup keys, hash objects can be used to retrieve data, store data, merge or join tables of data, and split a single table into multiple tables. You declare a hash object using the declare statement. Initializing variables in a data step that contains a hash object. You create, use and destroy the hash object in a data step. The hash object, introduced to the sas programming language in late 2003, increased the utility of sas data step programming by orders of magnitude. The hash object does not assign values to key variables for example, h.
Utilizing sas hash objects to accomplish many of the data joins and. Creating data sets from hash objects and updating contents of hash objects creating a data set from a hash object adding, modifying, and removing data from a hash selection from sas hash object programming made easy book. Using the hash object to store and retrieve data tree level 3. This weeks sas tip is from michele burlew and her new book sas hash object programming made easy.
An overview of hash objects hash object terminology and concepts basic hash object applications creating data sets from hash objects and ubdating contents of hash objects hash objects with multiple sets of data items per key value managing hash objects. Novice programmers can adapt some of the simpler hash programming techniques as they develop their sas programming skills. By group processing is part of the game when we work with data in sas. Sort the data, use the by statement in the data step or procedure. Hash object propaedeutics what is the sas hash object. Hashing functions and hash based message authentication code is added providing general information about hashing and hmac. The novel counting approach demonstrated in this paper involves the hash suminc. Hash objects, an efficient lookup tool in the sas data step, are objectoriented programming structures that function differently from traditional. In this paper, we outline the functionality of the hash object well beyond table lookup as a compendium of the book data management solutions using sas hash table operations. The hash data is defined to be mktrf, smb, hml, umd, rf. A hash object consists of key items and data items. An introduction to sas hash programming techniques kirk paul lafler, software intelligence corporation, spring valley, california abstract sas users are always interested in learning techniques that will help them improve the performance of table lookup, search, and sort operations.
For example, most marketing organizations will use sas to access data from a data warehouse in an rdbms. Find the power of hash how, why and when to use the sas. The usual approach for most sas programmers goes as follows. This book introduces you to hash object programming and connects it to concepts you. Typically sas programmers will extract data into temporary data sets and then. The hash iterator object is defined using a declare hiter statement that associates the hash iterator object with the name of the hash object you want to traverse.
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