### SAS programming - Using SAS function and Array - INPUT

**Assignment Detail:- ** ITECH3101 Business Analytics and Decision Support - Federation University
Exercise - SAS programming - Using SAS function and Array
Project 1: Knowing functions other than character functions
The SAS programming language has a rich assortment of functions that can greatly simplify some complex programming problems- We summarize some useful facts about SAS functions:• All SAS function names are followed by zero or more arguments-• Arguments to SAS functions can be variables, constants, expressions or even other functions-• Functions can only return a single values and , in most cases, the arguments to SAS functions do not change after the function is executed-
1- MISSING function
The MISSING function returns a value of true -1- if the argument is a missing value and false -0- otherwise- Argument of this function can be a character or numeric value-
Example
In above code, missing function tests if age is a missing value- If so, we assign a missing value to the variable age_group-
After clicking Run tap, we get:
2- INPUT and PUT functions
INPUT function performs character-to-numeric conversion, and PUT function performs numeric-to-character conversion-
IINPUT function performs character-to-numeric conversion- Its first argument is a character value, typically a character variable, and its second argument is the informat you want to use to associate with the first argument-
Example
In above code, double-trailing @@ symbol " holds the line strongly-" In other words, the reading pointer will move to the next record only if there are no more data values to be read on a line- Use the retain statement when you want SAS to preserve a variable's value from the previous iteration of the DATA step- In this program, we want to read data values that may either represent groups -'A' or 'B'- or numeric scores- Because we don't know if we'll be reading a character or a number, we read very value as a character and test if it is an 'A' or a 'B'- If not, we assume it is a score and use the INPUT function to convert the character variable to numeric- In the statement score = input-test,5--;, the first argument test includes a character such as 45, the second argument the informat -5-- is larger than we need - only need 2--- However, INPUT function will not read past the end of a character value, so there is no harm in choosing a large number for the numeric informat-
After clicking Run tap, we get:
PUT function performs numeric-to-character conversion- Its first argument is a numeric or character value, and its second argument is the format- either a built-in SAS format or one that you wrote-- PUT function takes the first argument, formats it using the second argument, and assigns the result to a character value-
Example
In above code, we use PROC FORMAT to create own formats- The FORMAT procedure creates formats that will later be associated with variables in a FOTMAT statement- The procedure starts with statement PROC FORMAT and continues with one or more VALUE statement:
PROC FORMAT;VALUE name range-1 = 'formatted-text-1'range-2 = 'formatted-text-2'--;
where name must start with a $ if the format is for character data- Each range is the value of a variable that is assigned to the text given in quotation marks on the right side of the equal sign-
In this example, we have a data about age and create a format that places the ages into four groups- The variable age4 is character variable with values of '1','2','3', or '4'-
After clicking Run tap, we get:
3- LAG and DIF functions
The LAG -lagged- function returns the value of its argument the last time the function executed- If we execute the LAG function for every iteration of DATA step, it returns the value of its argument from previous observation- In SAS, we may want to compare a data value from a current observation with a value form a previous observation and may also want to look back several observations-
Example
In above code, the variable up_down will be the current day's price minus the price from the previous day because the program is executing LAG function for every iteration of DATA step-
After clicking Run tap, we get:
DIF -X- function is equal to X - LAG-X-- We can substitute the line on the above program with up-down = dif-price-;
4- Arithmetic and mathematical functions
Some of the more common arithmetic and mathematical functions and their purposes are listed below:
Function name ActionLOG Base e logLOG10 Base 10 logSIN Sine of he argument-in radians-COS Cosine -in radians-TAN Tangent-in radians-INT Drops the fractional part of a numberSQRT Square root
Example
In above code, the program creates a new variable called loglos that is natural log of los -length of staying in hospital-- loglos will be written in data set func_eg and its values will be the natural -base e- log of los-
After clicking Run tap, we get:
Project 2: Character functions
In this project, we discuss some functions that deal with character values-
1- LENGTHE and LENGTHC functions
LENGTHN function returns the length of a character value, not counting trailing blanks- If the argument is a missing value, the function returns a 0- LENGTHC function returns the storage length of a character variable-
Example
After clicking Run tap, we get:
In above code, the variable string is assigned a length of 5 and the variable miss is assigned a length of 4- The lengthn function returns a 3, the length of string with the-2- trailing blanks removed- The storage length shows that string has a length of 5- The lengthn function returns a length of 0 for the variable miss while lengthc returns the storage length -4--
2- COMPRESS function- Remove characters from a string
The COMPRESS function can remove any number of specified characters from a character variable- With the 'k' modifier, we can use this function to extract characters- for example, all digits - from a string- This is one of the most powerful character functions in the SAS- If we provide only one argument- a character value-, this function removes blanks from the string- An optional second argument is a string of characters that we ant to remove from the first argument-
Some of more useful modifiers are:
Modifier Description'a' All upper- and lowercase letters'd' All digits'p' All punctuation-such as periods, commas,etc's' All whitespace characters-spaces, tabs-linefeeds, carriage returns-'i' Ignore case'k' Keep the specified characters; remove allothers- very useful-
Example
string1='abc def 123'; string2='-908- 782-1234'; string3='120 Lbs-';
-1- compress -string1-= abcdef123Because there is only one argument, compress function removes all blanks-
-2- compress-string1,'0123456789'- = abc def The second argument are removed-
-3- compress-string1,,'d'-= abc defUsing two commas tells the function that 'd' is the third argument-modifier- and you want to remove all digits- Note that using one comma means that 'd' is the second argument and you are trying to remove all 'd' from the string--4- compress-string2,,'kd'-= 9087821234This keeps digits and throws everything else away-
3- Character data verification
We sometimes want to be sure that only certain values are present in a character variable- In this case, we can use VERIFY function to test if there are any invalid characters present-
After clicking Run tap, we get:
In above code, only the values 'A','B','C','D', and 'E' are valid data values- To verify data, the VERIFY function inspects every character in the first argument, and if it finds any value not in the verify string -the second argument-, it will return the position of the first offending value- If all the values of the string are located in the verify string, a value of 0 is returned- In this program, for the first observation, p will be 0; in the second observation, p will be 3; in the third observation, p will be 1 and in the fourth observation, p will be 4-
Project 3: Using Array
In this project, we work on the usage of array- SAS arrays are good tools that can reduce the amount of coding in a SAS DATA step and save you huge amounts of time-A SAS array is a collection of SAS variables- Using the array name and a subscript, an array element can represent any one of the variables included in the array-
1- Converting all numeric values of 999 to missing values
In some applications, we may have certain data on a group of subjects such as age, height, and weight, etc- Missing values may be coded as 999 for each of these variables- In this case, we need to convert every value of 999 to a SAS missing value because SAS doesn't treat values of 999 as missing values-
In above code, the first iteration of the DO loop is statement: if miss-1- = 999 then miss-1- = -; , which becomes if age = 999 then age = - ;-
Once DO loop has finished, each of variables in the array have been processed- As we don't need to DO loop counter -i- in the output data set, so we use a DROP statement to remove it from the data set-
After clicking Run tap, we get:
2- Using temporary arrays
Temporary array does not actually refer to a list of variables- In other words, no real variables are created when you use a temporary array- You can declare an array to be temporary and use the array elements in their subscripted from in DATA step-
In above code, the program uses a temporary array to hold the passing scores on five exams- Students' scores are then read and compared to these passing scores, and the number of failed courses is recorded- We define a temporary array pass by using the keyword _temporary_ following the brackets- pass-1- through pass-5- keep five passing initial values of scores- The five passing scores are available for comparison to the student grades in every iteration of DATA step because values of temporary array elements are automatically retained- The array statement array score-5- is equivalent to array scores-5- score1-score5;- We place an asterisk in the brackets of array score-*- to save time of counting the number numeric variables in the array-
After clicking Run tap, we get:
Project 4- Answering questions -Please do this at your home by using your own computer-
1 What is the difference between white hat and black hat SEO-Search Engine Optimization- activities????
2- A data set -MANY- contains the variables X1-X5,Y1-Y5- First, run the following program to create this data set:
DATA MANY;INPUT X1-X5 Y1-Y5; DATALINES;1 2 3 4 5 6 7 8 9 103 - 5 - 7 5 - - - 159 8 - - - 4 4 4 4 1;
Write a program to include the following in data set MANY:-1- The mean-average- of the X1-X5-call it MEAN_X- and the mean of Y1-Y5- call it MEAN_Y-hint: use MEAN function such as MEAN-OF X1-X5--2- The minimum value of X1-X5-call it MIN_X- and the minimum value of Y1- Y5-call it MIN_Y--hint: use MIN function such as MIN-OF X1-X5---
3- Describe and explain the structure of a typical internet search engine
4- What were the challenges, the proposed solution, and the obtained results for IGN company to increase search traffic????
Project 5- Creating a Professional Report
Summarize the above experiments procedure, results, answering questions and screenshots -project 1, 2, 3, 4- into one report- Your report is the assignment that is required to be submitted for evaluation on week 11- Create a report by following below steps-
You can add a chapter called Chapter 9 in your previous report-
1- Open your last week's report and find the end of last week's report-2- Copy this week's related experimental results, your findings and Screenshots, and paste them at the end of last week's report-3- Delete original Table of Content you created-4- Select all content , align all text to both left and right margin5- Use shortcut key approach, generate Chapter 9: SAS programming -3 Using SAS function and Array6- Then use shortcut key approach to generate proper sub-chapters for this week's lab work-7- Insert Table of Contents to your report-
Attachment:- Using SAS function and Array-rar

## Post a Comment