Question

I need to control the data type when reading XML data in SAS. The XML data are written and accessed using the XML libname engine in SAS.

SAS seems to guess the data type based on the contents of a column: If I write ‘20081002’ to my XML data in a character column, it will be read back in as a numerical variable.

An example:

filename my_xml '/tmp/my.xml'; * Yes, I use SAS on Unix *; libname my_xml XML;  data my_xml.data_type_test;   text_char='This is obviously text';   date_char='20081002';   num_char='42';   genuine_num=42; run;  proc copy inlib=my_xml outlib=WORK; run;  libname my_xml; filename my_xml CLEAR; 

Only the last column is defined as numerical data type in the XML data, but when I copy it into my WORK library, only the column text_char is character. The other 3 are now numeric.

How can I control the data type when reading XML data in SAS?

Answer 1

Take a look at the SAS XML Mapper. It allows you to create a map to read (and wrte in 9.2) XML files and specifying column attributes.

If this is your XML file:

This is obviously text 20081002 42 42 You could create a MAP like this:

<!-- ############################################################ --> <TABLE name='DATA_TYPE_TEST'>     <TABLE-PATH syntax='XPath'>/TABLE/DATA_TYPE_TEST</TABLE-PATH>      <COLUMN name='text_char'>         <PATH syntax='XPath'>/TABLE/DATA_TYPE_TEST/text_char</PATH>         <TYPE>character</TYPE>         <DATATYPE>string</DATATYPE>         <LENGTH>22</LENGTH>     </COLUMN>      <COLUMN name='date_char'>         <PATH syntax='XPath'>/TABLE/DATA_TYPE_TEST/date_char</PATH>         <TYPE>numeric</TYPE>         <DATATYPE>integer</DATATYPE>         <FORMAT width='9'>DATE</FORMAT>         <INFORMAT width='8'>ND8601DA</INFORMAT>     </COLUMN>      <COLUMN name='num_char'>         <PATH syntax='XPath'>/TABLE/DATA_TYPE_TEST/num_char</PATH>         <TYPE>character</TYPE>         <DATATYPE>string</DATATYPE>         <LENGTH>2</LENGTH>     </COLUMN>      <COLUMN name='genuine_num'>         <PATH syntax='XPath'>/TABLE/DATA_TYPE_TEST/genuine_num</PATH>         <TYPE>numeric</TYPE>         <DATATYPE>integer</DATATYPE>     </COLUMN>  </TABLE> 

And then read the XML file:

filename  my 'C:\temp\my.xml'; filename  SXLEMAP 'C:\temp\MyMap.map'; libname   my xml xmlmap=SXLEMAP access=READONLY;  title 'Table DATA_TYPE_TEST'; proc contents data=my.DATA_TYPE_TEST varnum;  run; proc print data=my.DATA_TYPE_TEST(obs=10);  run; 

Result:

Table DATA_TYPE_TEST  The CONTENTS Procedure  Data Set Name        MY.DATA_TYPE_TEST    Observations             Member Type          DATA                 Variables             4  Engine               XML                  Indexes               0  Created              .                    Observation Length    0  Last Modified        .                    Deleted Observations  0  Protection                                Compressed            NO Data Set Type                             Sorted                NO Label                                                              Data Representation  Default                                       Encoding             Default                                         Variables in Creation Order  #    Variable       Type    Len    Format    Informat      Label  1    text_char      Char     22    $22.      $22.          text_char   2    date_char      Num       8    DATE9.    ND8601DA8.    date_char   3    num_char       Char      2    $2.       $2.           num_char    4    genuine_num    Num       8    F8.       F8.           genuine_num  Table DATA_TYPE_TEST                                                                 genuine_      Obs    text_char                 date_char    num_char      num         1    This is obviously text    02OCT2008       42             42