Madanswer Technologies Interview Questions Data|Agile|DevOPs|Python - Recent questions and answers in Software Defined Networking

Answered: Two ways to reverse order of data

Mon, 26 Aug 2024 15:35:09 +0000

Reverse order of data

Answered: How to combine tables vertically with PROC SQL

Mon, 26 Aug 2024 15:34:48 +0000

PROC SQL : Combine tables vertically

Answered: Use of Multiple SET Statments

Mon, 26 Aug 2024 15:34:30 +0000

SAS : Use of Multiple SET Statements

Answered: What is the use of 'BY statement' in Data Step Merge?

Mon, 26 Aug 2024 15:34:12 +0000

Without 'BY' statement, Data Step Merge performs merging without matching. In other words, the records are combined based on their relative position in the data set. The second data set gets placed to the "right" of the first data set (no matching based on the unique identifier - if data is not sorted based on unique identifier, wrong records can be merged).

When you use 'BY' statement, it matches observations according to the values of the BY variables that you specify.

Answered: How Data Step Merge and PROC SQL handle many-to-many relationship?

Mon, 26 Aug 2024 15:33:53 +0000

Data Step MERGE does not create a cartesian product incase of a many-to-many relationship. Whereas, Proc SQL produces a cartesian product.

SAS : Many-to-Many Merge

Answered: How to save log in an external file

Mon, 26 Aug 2024 15:33:32 +0000

Use PROC PRINTTO

proc printto log="C:\Users\Deepanshu\Downloads\LOG2.txt" new;

run;

Answered: How to debug SAS Macros

Mon, 26 Aug 2024 15:33:08 +0000

There are some system options that can be used to debug SAS Macros: MPRINT, MLOGIC, SYMBOLGEN.

Answered: Difference between %EVAL and %SYSEVALF

Mon, 26 Aug 2024 15:32:47 +0000

%EVAL cannot perform arithmetic calculations with operands that have the floating point values. It is when the %SYSEVALF function comes into picture.

%let last=%eval (4.5+3.2);

%let last2=%sysevalf(4.5+3.2);

%put &last2;

Answered: How to merge two data sets using PROC SQL?

Mon, 26 Aug 2024 15:32:28 +0000

PROC SQL Merging

Answered: How to count unique values by a grouping variable?

Mon, 26 Aug 2024 15:32:09 +0000

You can use PROC SQL with COUNT(DISTINCT variable_name) to determine the number of unique values for a column.

Answered: How to remove duplicates using PROC SQL?

Mon, 26 Aug 2024 15:31:52 +0000

Proc SQL noprint;

Create Table mergedtbl as

Select distinct * from readin ;

Quit;

Answered: How to use IF THEN ELSE in PROC SQL?

Mon, 26 Aug 2024 15:31:31 +0000

PROC SQL;

SELECT WEIGHT,

CASE

WHEN WEIGHT BETWEEN 0 AND 50 THEN ’LOW’

WHEN WEIGHT BETWEEN 51 AND 70 THEN ’MEDIUM’

WHEN WEIGHT BETWEEN 71 AND 100 THEN ’HIGH’

ELSE ’VERY HIGH’

END AS NEWWEIGHT FROM HEALTH;

QUIT;

Answered: When grouping is in effect, can the WHERE clause be used in PROC SQL to subset data?

Mon, 26 Aug 2024 15:31:08 +0000

No. In order to subset data when grouping is in effect, the HAVING clause must be used. The variable specified in having clause must contain summary statistics.

PROC SQL Made Easy

Answered: For what purpose would you use the RETAIN statement?

Mon, 26 Aug 2024 15:30:48 +0000

A RETAIN statement tells SAS not to set variables to missing when going from the current iteration of the DATA step to the next. Instead, SAS retains the values.

Answered: The following data step executes:

Mon, 26 Aug 2024 15:30:24 +0000

* DONALD DUCK [(Leading blanks are displayed using an asterisk *]

Answered: Difference between SCAN and SUBSTR?

Mon, 26 Aug 2024 15:29:57 +0000

SCAN extracts words within a value that is marked by delimiters. SUBSTR extracts a portion of the value by stating the specific location. It is best used when we know the exact position of the sub string to extract from a character value.

Answered: How to count the number of intervals between two given SAS dates?

Thu, 22 Aug 2024 14:43:04 +0000

INTCK(interval,start-of-period,end-of-period) is an interval function that counts the number of intervals between two give SAS dates, Time and/or datetime.

Answered: Which date function advances a date, time or datetime value by a given interval?

Thu, 22 Aug 2024 14:42:40 +0000

The INTNX Function advances a date, time, or datetime value by a given interval, and returns a date, time, or datetime value. Example : INTNX(interval,start-from,number-of-increments,alignment).

Answered: What are SYMGET and SYMPUT?

Thu, 22 Aug 2024 14:42:18 +0000

SYMPUT puts the value from a dataset into a macro variable where as SYMGET gets the value from the macro variable to the dataset.

Answered: Use of CALL SYMPUT

Thu, 22 Aug 2024 14:41:58 +0000

CALL SYMPUT puts the value from a dataset into a macro variable.

proc means data=test;

var x;

output out=testmean mean=xbar;

run;

data _null_;

set testmean;

call symput("xbarmac",xbar);

run;

%put mean of x is &xbarmac;

Answered: Describe the ways in which you can create macro variables

Thu, 22 Aug 2024 14:41:39 +0000

There are 5 ways to create macro variables:

%Let

Iterative %DO statement

Call Symput

Proc SQl into clause

Macro Parameters.

Detailed Tutorial : SAS Macros Made Easy

Answered: How to count missing values for all variables?

Thu, 22 Aug 2024 14:41:17 +0000

proc format;

value $missfmt ' '='Missing' other='Not Missing';

value missfmt .='Missing' other='Not Missing';

run;

proc freq data=one;

format _CHAR_ $missfmt.;

tables _CHAR_ / missing missprint nocum nopercent;

format _NUMERIC_ missfmt.;

tables _NUMERIC_ / missing missprint nocum nopercent;

run;

Answered: How to count missing values for numeric variables?

Thu, 22 Aug 2024 14:40:54 +0000

Use PROC MEANS with NMISS option.

Types of Missing Values in SAS

Answered: How to generate detailed summary statistics?

Thu, 22 Aug 2024 14:40:35 +0000

Use PROC UNIVARIATE code.

PROC UNIVARIATE DATA=READIN;

CLASS Age;

VAR Q1;

RUN;

Note : Q1 is a numeric variable and Age a grouping variable.

Answered: How to generate cross tabulation?

Thu, 22 Aug 2024 14:40:15 +0000

Use PROC FREQ code.

PROC FREQ DATA=auto;

TABLES A*B ;

RUN;

SAS will produce table of A by B.

Answered: How to calculate mean for a variable by group?

Thu, 22 Aug 2024 14:39:52 +0000

Suppose Q1 is a numeric variable and Age a grouping variable. You wish to compute mean for Q1 by Age.

PROC MEANS DATA=READIN;

VAR Q1;

CLASS AGE;

RUN;

Answered: How to use arrays to recode all the numeric variables?

Thu, 22 Aug 2024 14:39:32 +0000

Use _numeric_ and dim functions in array.

data readin;

set outdata;

array Q(*) _numeric_;

do i=1 to dim(Q);

if Q(i)=6 then Q(i)=.;

end;

run;

Note : DIM returns a total count of the number of elements in array dimension Q.

Answered: How to use arrays to recode set of variables?

Thu, 22 Aug 2024 14:39:11 +0000

Recode the set of questions: Q1,Q2,Q3...Q20 in the same way: if the variable has a value of 6 recode it to SAS missing.

data readin;

set outdata;

array Q(20) Q1-Q20;

do i=1 to 20;

if Q(i)=6 then Q(i)=.;

end;

run;

Answered: How to label values and use it in PROC FREQ?

Thu, 22 Aug 2024 02:28:18 +0000

Use PROC FORMAT to set up a format.

proc format;

value score 0 - 100=‘100-‘

101 - 200=‘101+’

other=‘others’

;

proc freq data=readin;

tables outdata;

format outdatascore. ;

run;

Answered: How do I create a data set with observations=100, mean 0 and standard deviation 1?

Thu, 22 Aug 2024 02:27:54 +0000

data readin;

do i=1 to 100;

temp=0 + rannor(1) * 1;

output;

end;

run;

proc means data=readin mean stddev;

var temp;

run;

Answered: How to do Matched Merge and output consisting of observations from only file1?

Thu, 22 Aug 2024 02:27:31 +0000

data readin;

merge file1(in=infile1)file2(in=infile2);

by id;

if infile1;

run;

Answered: How to do Matched Merge and output consisting of observations in file1 but not in file2, or in file2 but not in file1?

Thu, 22 Aug 2024 02:27:07 +0000

data readin;

merge file1(in=infile1)file2(in=infile2);

by id;

if infile1 ne infile2;

run;

SAS Merge

Answered: How to do Matched Merge and output only consisting of observations from both files?

Thu, 22 Aug 2024 02:26:47 +0000

Use IN=variable in MERGE statements. It is used for matched merge to track and select which observations in the data set from the merge statement will go to a new data set.

data readin;

merge file1(in=infile1) file2(in=infile2);

by id;

if infile1=infile2;

run;

Answered: Difference between SET and MERGE?

Thu, 22 Aug 2024 02:26:23 +0000

SET concatenates the data sets where as MERGE matches the observations of the data sets.

SET

SAS SET STATEMENT

MERGE

Join Horizontally

Detailed Explanation : Data Step Merging

Detailed Explanation : Combine Data Sets

Answered: Difference between CEIL and FLOOR functions?

Thu, 22 Aug 2024 02:25:58 +0000

The ceil function returns the smallest integer greater than/equal to the argument whereas the floor returns the greatest integer less than/equal to the argument.

For example : ceil(4.4) returns 5 whereas floor(4.4) returns 4.

Answered: How SUBSTR function works?

Thu, 22 Aug 2024 02:25:31 +0000

The SUBSTR function is used to extract substring from a character variable.

The SUBSTR function has three arguments:

SUBSTR ( character variable, starting point to begin reading the variable, number of characters to read from the starting point)

There are two basic applications of the SUBSTR function:

RIGHT SIDE APPLICATION

data _null_;

phone='(312) 555-1212';

area_cd=substr(phone, 2, 3);

put area_cd=;

run;

Result : In the log window, it writes area_cd=312 .

LEFT SIDE APPLICATION

It is used to change just a few characters of a variable.

data _null_ ;

phone='(312) 555-1212' ;

substr(phone, 2, 3)='773' ;

put phone=;

run ;

Result : The variable PHONE has been changed from(312) 555-1212 to (773) 555-1212.

Answered: Can PROC MEANS analyze ONLY the character variables?

Thu, 22 Aug 2024 02:25:10 +0000

No, Proc Means requires at least one numeric variable.

Answered: What's the difference between VAR A1 - A3 and VAR A1 -- A3?

Tue, 20 Aug 2024 15:22:08 +0000

Single Dash : It is used to specify consecutively numbered variables. A1-A3 implies A1, A2 and A3.

Double Dash : It is used to specify variables based on the order of the variables as they appear in the file,regardless of the name of the variable. A1--A3 implies all the variables from A1 to A3 in the order they appear in the data set.

Example : The order of variables in a data set : ID Name A1 A2 C1 A3

So using A1-A3 would return A1 A2 A3. A1--A3 would return A1 A2 C1 A3.

Answered: How to convert a character variable to a numeric variable?

Tue, 20 Aug 2024 15:21:39 +0000

You must create a differently-named variable using theINPUTfunction.

The example below shows the use of the INPUT function.

numvar=input(charvar,4.0);

Answered: How to convert a numeric variable to a character variable?

Tue, 20 Aug 2024 15:21:20 +0000

You must create a differently-named variable using the PUT function.

The example below shows the use of the PUT function.

charvar=put(numvar, 7.) ;

Answered: Under what circumstances would you code a SELECT construct instead of IF statements?

Tue, 20 Aug 2024 15:20:59 +0000

When you have a long series of mutually exclusive conditions and the comparison is numeric, using a SELECT group is slightly more efficient than using IF-THEN or IF-THEN-ELSE statements because CPU time is reduced.

The syntax for SELECT WHEN is as follows :

SELECT (condition);

WHEN (1) x=x;

WHEN (2) x=x*2;

OTHERWISE x=x-1;

END;

Example :

SELECT (str);

WHEN ('Sun') wage=wage*1.5;

WHEN ('Sat') wage=wage*1.3;

OTHERWISE DO;

wage=wage+1;

bonus=0;

END;

Answered: How to sort in descending order?

Tue, 20 Aug 2024 15:20:37 +0000

Use DESCENDING keyword in PROC SORT code. The example below shows the use of the descending keyword.

PROC SORT DATA=auto;

BY DESCENDING engine ;

RUN ;

Answered: What are _numeric_ and _character_ and what do they do?

Tue, 20 Aug 2024 15:20:10 +0000

1. _NUMERIC_ specifies all numeric variables that are already defined in the current DATA step.

2. _CHARACTER_ specifies all character variables that are currently defined in the current DATA step.

3. _ALL_ specifies all variables that are currently defined in the current DATA step.

Example : To include all the numeric variables in PROC MEANS.

proc means;

var _numeric_;

run;

Answered: Difference between NODUP and NODUPKEY Options?

Tue, 20 Aug 2024 15:19:46 +0000

The NODUPKEY option removes duplicate observations where value of a variable listed in BY statement is repeated while NODUP option removes duplicate observations where values in all the variables are repeated (identical observations).

Answered: How to identify and remove unique and duplicate values?

Tue, 20 Aug 2024 15:19:18 +0000

1. Use PROC SORT with NODUPKEY and NODUP Options.

2. Use First. and Last. Variables - Detailed Explanation

The detailed explanation is shown below :

SAMPLE DATA SET

ID Name Score

1 David 45

1 David 74

2 Sam 45

2 Ram 54

3 Bane 87

3 Mary 92

3 Bane 87

4 Dane 23

5 Jenny 87

5 Ken 87

6 Simran 63

8 Priya 72

Create this data set in SAS

data readin;

input ID Name $ Score;

cards;

1 David 45

1 David 74

2 Sam 45

2 Ram 54

3 Bane 87

3 Mary 92

3 Bane 87

4 Dane 23

5 Jenny 87

5 Ken 87

6 Simran 63

8 Priya 72;

run;

There are several ways to identify and remove unique and duplicate values:

PROC SORT

In PROC SORT, there are two options by which we can remove duplicates.

1. NODUPKEY Option 2. NODUP Option

PROC SORT DATA=readin NODUPKEY;

BY ID;

RUN;

PROC SORT DATA=readin NODUP;

BY ID;

RUN;

The output is shown below :

SAS : NODUPKEY vs NODUP

The NODUPKEY has deleted 5 observations with duplicate values whereas NODUP has not deleted any observations.

Answered: What is the difference between '+' operator and SUM function?

Tue, 20 Aug 2024 15:18:50 +0000

SUM function returns the sum of non-missing arguments whereas “+” operator returns a missing value if any of the arguments are missing.

Suppose we have a data set containing three variables - X, Y and Z. They all have missing values. We wish to compute sum of all the variables.

data mydata2;

set mydata;

a=sum(x,y,z);

p=x+y+z;

run;

The output is shown in the image below :

SUM Function vs PLUS Operator

SAS : SUM Function vs Plus Operator

In the output, value of p is missing for 4th, 5th and 6th observations.

Answered: What is DATA _NULL_?

Tue, 20 Aug 2024 15:18:30 +0000

The DATA _NULL_ is mainly used to create macro variables. It can also be used to write output without creating a dataset.The idea of "null" here is that we have a data step that actually doesn't create a data set.

Answered: How PDV is created?

Tue, 20 Aug 2024 15:18:13 +0000

SAS creates a dataset one observation at a time.Input buffer is created at the time of compilation, for holding a record from external file.PDV is created followed by the creation of input buffer.SAS builds dataset in the PDV area of memory.

Answered: What is Program Data Vector (PDV)?

Tue, 20 Aug 2024 15:17:52 +0000

PDV is a logical area in the memory.

Answered: Differences between WHERE and IF statement?

Mon, 19 Aug 2024 22:13:30 +0000

For detailed explanation, see this tutorial -SAS : Where Vs IF

WHERE statement can be used in procedures to subset data while IF statement cannot be used in procedures.

WHERE can be used as a data set option while IF cannot be used as a data set option.

WHERE statement is more efficient than IF statement. It tells SAS not to read all observations from the data set

WHERE statement can be used to search for all similar character values that sound alike while IF statement cannot be used.

WHERE statement can not be used when reading data using INPUT statement whereas IF statement can be used.

Multiple IF statements can be used to execute multiple conditional statements

When it is required to use newly created variables, useIF statement as it doesn't require variables to exist in the READIN data set