topic Re: Question on Pointer Location with List Input in SAS Programming

Question on Pointer Location with List Input

cosmid — Thu, 10 Jan 2019 18:50:03 GMT

Noob question. I was reading a document from SAS support about List Inputs. The example given below is from their website. My question is why the pointer is located in column 5 and not column 4 after the value red is read?

data scores;

input Team $ Score;

datalines;

red 59

blue 95

yellow 63

green 76

;

The following figure shows that the pointer is located in column 5 after the value red is read. Because Score, the next variable, is read with list input, the pointer scans for the next nonblank space before it begins to read a value for Score. Unlike column and formatted input, you do not have to explicitly move the pointer to the beginning of the next field in list input.

Pointer Position: List Input

Link of original document, the above is at the very bottom of the page:

http://support.sas.com/documentation/cdl/en/basess/58133/HTML/default/viewer.htm#a002645710.htm

Re: Question on Pointer Location with List Input

Astounding — Thu, 10 Jan 2019 19:04:40 GMT

With LIST input, SAS has to read across the line until it finds a blank. That's how it knows it has found all the characters. So to find "red" as the value, SAS has to read the blank in column 4. That's how it knows it has found all the nonblank characters, and it's why the pointer is now at column 5.

Re: Question on Pointer Location with List Input

data_null__ — Thu, 10 Jan 2019 19:07:16 GMT

From the document you reference.

 With list input, the pointer reads until a blank is reached and then stops in the next column

Re: Question on Pointer Location with List Input

novinosrin — Thu, 10 Jan 2019 19:12:40 GMT

How i understand:

Both list and column/formatted points to 1 column to the right after reading values.

List input :read until delimiter is found (this makes it an extra read--so in your example if red-3bytes read+1 until delim makes it 4, and then as mentioned above move 1 to the right)

Column/formatted : read exactly specified by the format width/number range in the input statement, then as usual move 1 column to the right

Re: Question on Pointer Location with List Input

Tom — Thu, 10 Jan 2019 19:26:25 GMT

Note also that with LIST mode it is not always SPACE characters that it is used to mark the end of a field. It is whatever characters are included in the DLM= option of the INFILE statement. Space is the default, unless the DSD option is specified. The DSD option changes the default to comma instead.

Similar behavior when using the DLMSTR= option also. Cursor is left at the character after the end of the delimiter string that was found.

Re: Question on Pointer Location with List Input

data_null__ — Thu, 10 Jan 2019 19:32:39 GMT

@Tom wrote:

Note also that with LIST mode it is not always SPACE characters that it is used to mark the end of a field. It is whatever characters are included in the DLM= option of the INFILE statement. Space is the default, unless the DSD option is specified. The DSD option changes the default to comma instead.

Similar behavior when using the DLMSTR= option also. Cursor is left at the character after the end of the delimiter string that was found.

DSD also changes the way consecutive delimiters are handled. I'm not sure about pointer position for consecutive delimiters, reckon I need to find out.

Re: Question on Pointer Location with List Input

Tom — Thu, 10 Jan 2019 20:52:30 GMT

@data_null__ wrote:

@Tom wrote:

...

DSD also changes the way consecutive delimiters are handled. I'm not sure about pointer position for consecutive delimiters, reckon I need to find out.

I think the DSD option changes what happens when a read STARTS with the current position containing a delimiter. Without DSD all of the leading delimiters are skipped and the read starts with the next non-delimiter. With DSD a null value is used for the current read and the cursor advances past the delimiter.

Re: Question on Pointer Location with List Input

cosmid — Mon, 14 Jan 2019 15:10:46 GMT

Sorry everyone for accepting a solution so late. I wasn't getting any notifications for this post and I thought I have asked a stupid question. Checked my email today and saw it. Again, my apologies. And thanks for all the great inputs!

@data_null__ I can't believe I missed it when reading the document. Thanks for pointing it out!