Reading Unaligned Data

The simplest form of the INPUT statement uses list input. List input is used to read data values that are separated by a delimiter character (by default, a blank space). With list input, SAS reads a data value until it encounters a blank space. SAS assumes the value has ended and assigns the data to the appropriate variable in the program data vector. SAS continues to scan the record until it reaches a nonblank character again. SAS reads a data value until it encounters a blank space or the end of the input record.

This program uses the health and fitness club data from Introduction to DATA Step Processing to illustrate a DATA step that uses list input in an INPUT statement.

data club1;
   input IdNumber Name $ Team $ StartWeight EndWeight;3 
   datalines;1 
1023 David red 189 165 2 
1049 Amelia yellow 145 124 
1219 Alan red 210 192 
1246 Ravi yellow 194 177 
1078 Ashley red 127 118 
1221 Jim yellow 220 . 2 
; 1  

proc print data=club1;
   title 'Weight of Club Members';
run;

The following list corresponds to the numbered items in the preceding program:

The output that follows shows the resulting data set. The PROC PRINT statement that follows the DATA step produces this listing.

Data Set Created with List Input

                             Weight of Club Members                            1

                      Id                           Start      End
             Obs    Number    Name      Team      Weight    Weight

              1      1023     David     red         189       165 
              2      1049     Amelia    yellow      145       124 
              3      1219     Alan      red         210       192 
              4      1246     Ravi      yellow      194       177 
              5      1078     Ashley    red         127       118 
              6      1221     Jim       yellow      220         . 

This program also uses the health and fitness club data but notice that here the data is delimited by a comma instead of a blank space, the default delimiter.

options pagesize=60 linesize=80 pageno=1 nodate;
data club1; 
   infile datalines2  dlm=','3 ;
   input IdNumber Name $ Team $ StartWeight EndWeight;
   datalines;
1023,David,red,189,1651  
1049,Amelia,yellow,145,124 
1219,Alan,red,210,192 
1246,Ravi,yellow,194,177 
1078,Ashley,red,127,118 
1221,Jim,yellow,220,. 
;  
proc print data=club1;
   title 'Weight of Club Members';
run;

The following list corresponds to the numbered items in the preceding output:

Reading Data Delimited by Commas

                             Weight of Club Members                            1

                      Id                           Start      End
             Obs    Number    Name      Team      Weight    Weight

              1      1023     David     red         189       165 
              2      1049     Amelia    yellow      145       124 
              3      1219     Alan      red         210       192 
              4      1246     Ravi      yellow      194       177 
              5      1078     Ashley    red         127       118 
              6      1221     Jim       yellow      220         . 

The points to remember when you use list input are:

• Use list input when each field is separated by at least one blank space or delimiter.

• Specify each field in the order that they appear in the records of raw data.

• Represent missing values by a placeholder such as a period. (Under the default behavior, a blank field causes the variable names and values to become mismatched.)

• Character values cannot contain embedded blanks.

• The default length of character variables is eight bytes. SAS truncates a longer value when it writes the value to the program data vector. (To read a character variable that contains more than eight characters with list input, use a LENGTH statement. See Defining Enough Storage Space for Variables.)

• Data must be in standard character or numeric format (that is, it can be read without an informat).

Note:   List input requires the fewest specifications in the INPUT statement. However, the restrictions that are placed on the data may require that you learn to use other styles of input to read your data. For example, column input, which is discussed in the next section, is less restrictive. This section has introduced only simple list input. See Understanding How to Make List Input More Flexible to learn about modified list input.  

Copyright © 2007 by SAS Institute Inc., Cary, NC, USA. All rights reserved.