m14 - reading sas data sets - 30 of 32.mht

sas的考试样题

      variables, FIRST. and LAST. When you specify <A=20
      onmouseover=3D"window.status=3D'Display details on multiple BY =
variables.';"=20
      onclick=3DsuggestBack() onmouseout=3D"window.status=3D''"=20
      =
href=3D"http://www.sas.com/apps/OLTRN/59080/m14/m14_11.htm">multiple BY=20
      variables</A>, a change in the value of a primary BY variable =
forces=20
      <CODE>LAST.<EM>variable</EM></CODE> to equal <EM>1</EM> for the =
secondary=20
      BY variables.=20
      <P><STRONG>Reading Observations Using Direct Access</STRONG><BR>In =

      addition to reading input data sequentially, you can <A=20
      onmouseover=3D"window.status=3D'Display details on the POINT=3D =
option.';"=20
      onclick=3DsuggestBack() onmouseout=3D"window.status=3D''"=20
      href=3D"http://www.sas.com/apps/OLTRN/59080/m14/m14_14.htm">access =

      observations directly</A> by using the POINT=3D option to go =
directly to a=20
      data set observation. There is no end-of-file condition when you =
use=20
      direct access, so include an explicit <A=20
      onmouseover=3D"window.status=3D'Display details on the OUTPUT =
statement.';"=20
      onclick=3DsuggestBack() onmouseout=3D"window.status=3D''"=20
      href=3D"http://www.sas.com/apps/OLTRN/59080/m14/m14_16.htm">OUTPUT =

      statement</A> and then the <A=20
      onmouseover=3D"window.status=3D'Display details on the STOP =
statement.';"=20
      onclick=3DsuggestBack() onmouseout=3D"window.status=3D''"=20
      href=3D"http://www.sas.com/apps/OLTRN/59080/m14/m14_15.htm">STOP=20
      statement</A> to prevent continuous looping.=20
      <P><STRONG>Detecting the End of a Data Set</STRONG><BR>To =
determine when=20
      the <A onmouseover=3D"window.status=3D'Display details on the =
END=3D option.';"=20
      onclick=3DsuggestBack() onmouseout=3D"window.status=3D''"=20
      href=3D"http://www.sas.com/apps/OLTRN/59080/m14/m14_17.htm">last=20
      observation</A> in an input data set has been read, use the END=3D =
option in=20
      the SET statement. The specified variable is initialized to =
<EM>0</EM>,=20
      then set to <EM>1</EM> when the SET statement reads the last =
observation=20
      of the data set. </P></TD></TR></TBODY></TABLE><!-- =
InstanceEndEditable --><BR>
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<P><!-- InstanceBeginEditable name=3D"syntax" -->
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    <TD><STRONG><A name=3DSyntax>Syntax</A></STRONG>=20
      <P><EM>To go to the page where a statement or option was =
presented, select=20
      a link.</EM>=20
      <P>
      <BLOCKQUOTE>
        <DL>
          <DT><FONT color=3D#003399><STRONG>LIBNAME</STRONG> =
<EM>libref</EM>=20
          =
<STRONG>'</STRONG><EM>SAS-data-library</EM><STRONG>';</STRONG></FONT>=20
          <DT><FONT color=3D#003399><A=20
          onmouseover=3D"window.status=3D'Display details on the DATA =
statement.';"=20
          onclick=3DsuggestBack() onmouseout=3D"window.status=3D''"=20
          =
href=3D"http://www.sas.com/apps/OLTRN/59080/m14/m14_2.htm"><STRONG>DATA</=
STRONG>=20
          <EM>&lt;SAS-data-set&gt;</EM></A> <A=20
          onmouseover=3D"window.status=3D'Display details on the KEEP=3D =
option.';"=20
          onclick=3DsuggestBack() onmouseout=3D"window.status=3D''"=20
          =
href=3D"http://www.sas.com/apps/OLTRN/59080/m14/m14_7.htm">(<STRONG>KEEP=3D=
=20
          </STRONG><EM>variable-1=20
          &lt;...variable-n&gt;</EM>)<STRONG>;</STRONG></A></FONT>=20
          <DD><NOBR><FONT color=3D#003399><A=20
          onmouseover=3D"window.status=3D'Display details on the SET =
statement.';"=20
          onclick=3DsuggestBack() onmouseout=3D"window.status=3D''"=20
          =
href=3D"http://www.sas.com/apps/OLTRN/59080/m14/m14_2.htm"><STRONG>SET</S=
TRONG>=20
          <EM>SAS-data-set</EM></A> <A=20
          onmouseover=3D"window.status=3D'Display details on the DROP=3D =
option.';"=20
          onclick=3DsuggestBack() onmouseout=3D"window.status=3D''"=20
          =
href=3D"http://www.sas.com/apps/OLTRN/59080/m14/m14_7.htm">(<STRONG>DROP=3D=
</STRONG>=20
          <EM>variable-1 &lt;...variable-n&gt;</EM>)</A></FONT></NOBR>=20
          =
<DD><NOBR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT=20
          color=3D#003399><A=20
          onmouseover=3D"window.status=3D'Display details on the =
POINT=3D option.';"=20
          onclick=3DsuggestBack() onmouseout=3D"window.status=3D''"=20
          =
href=3D"http://www.sas.com/apps/OLTRN/59080/m14/m14_14.htm"><STRONG>POINT=
=3D</STRONG><EM>variable</EM></A>=20
          | <A=20
          onmouseover=3D"window.status=3D'Display details on the END=3D =
option.';"=20
          onclick=3DsuggestBack() onmouseout=3D"window.status=3D''"=20
          =
href=3D"http://www.sas.com/apps/OLTRN/59080/m14/m14_17.htm"><STRONG>END=3D=
</STRONG><EM>variable</EM><STRONG>;</STRONG></A></FONT></NOBR>=20

          <DD><A=20
          onmouseover=3D"window.status=3D'Display details on the OUTPUT =
statement.';"=20
          onclick=3DsuggestBack() onmouseout=3D"window.status=3D''"=20
          =
href=3D"http://www.sas.com/apps/OLTRN/59080/m14/m14_16.htm"><FONT=20
          color=3D#003399><STRONG>OUTPUT</STRONG>=20
          &lt;<EM>SAS-data-set</EM>&gt;<STRONG>;</STRONG></FONT></A>=20
          <DD><A=20
          onmouseover=3D"window.status=3D'Display details on the STOP =
statement.';"=20
          onclick=3DsuggestBack() onmouseout=3D"window.status=3D''"=20
          =
href=3D"http://www.sas.com/apps/OLTRN/59080/m14/m14_15.htm"><FONT=20
          color=3D#003399><STRONG>STOP;</STRONG></FONT></A>=20
          <DT><FONT color=3D#003399><STRONG>RUN;</STRONG></FONT>=20
      </DT></DL></BLOCKQUOTE></TD></TR></TBODY></TABLE>
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<P><!-- InstanceBeginEditable name=3D"sampleprogram" -->
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    <TD align=3Dleft><STRONG><A name=3DSample>Sample =
Program</A></STRONG> <PRE>     <FONT color=3D#003399>proc sort =
data=3Dcompany.usa out=3Dwork.temp2;</FONT>
        <FONT color=3D#003399>by manager jobtype;</FONT>
     <FONT color=3D#003399>data company.budget2(keep=3Dmanager jobtype =
payroll);</FONT>
        <FONT color=3D#003399>set work.temp2;</FONT>
        <FONT color=3D#003399>by manager jobtype;</FONT>
        <FONT color=3D#003399>if wagecat=3D'S' then =
Yearly=3Dwagerate*12;</FONT>
        <FONT color=3D#003399>else if wagecat=3D'H' then =
Yearly=3Dwagerate*2000;</FONT>
        <FONT color=3D#003399>if first.jobtype then Payroll=3D0;</FONT>
        <FONT color=3D#003399>payroll+yearly;</FONT>
        <FONT color=3D#003399>if last.jobtype;</FONT>
     <FONT color=3D#003399>run;</FONT>

     <FONT color=3D#003399>data work.getobs5(drop=3Dobsnum);</FONT>
        <FONT color=3D#003399>obsnum=3D5;</FONT>
        <FONT color=3D#003399>set company.usa(keep=3Dmanager payroll) =
point=3Dobsnum;</FONT>
        <FONT color=3D#003399>output;</FONT>
        <FONT color=3D#003399>stop;</FONT>
     <FONT color=3D#003399>run;</FONT>

     <FONT color=3D#003399>data work.addtoend(drop=3Dtimemin =
timesec);</FONT>
        <FONT color=3D#003399>set clinic.stress2(keep=3Dtimemin timesec) =
end=3Dlast;</FONT>
        <FONT color=3D#003399>TotalMin+timemin;</FONT>
        <FONT color=3D#003399>TotalSec+timesec;</FONT>
        <FONT color=3D#003399>TotalTime=3Dtotalmin*60+timesec;</FONT>
        <FONT color=3D#003399>if last;</FONT>
     <FONT color=3D#003399>run;</FONT></PRE>
      <P>
      <HR>
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<P><!-- InstanceBeginEditable name=3D"pointstoremember" -->
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    <TD align=3Dleft><STRONG><A name=3DPoints>Points to =
Remember</A></STRONG>=20
      <UL>
        <LI>When you perform BY-group processing, the data sets listed =
in the=20
        SET statement must either be sorted by the values of the BY =
variable(s),=20
        or they must have an appropriate index.<BR><BR>
        <LI>When using direct access to read data, you =
<STRONG>must</STRONG>=20
        prevent continuous looping. Add a STOP statement to the DATA =
step, or=20
        use programming logic that checks for an invalid value of the =
POINT=3D=20
        variable.<BR><BR>
        <LI>Do not specify the END=3D option with the POINT=3D option in =
a SET=20
        statement.=20
</LI></UL></TD></TR></TBODY></TABLE><!-- InstanceEndEditable =
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    <TD width=3D14><IMG height=3D7 alt=3D""=20
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src=3D"http://www.sas.com/apps/elearning/images/en/navimages/linebox.gif"=
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      width=3D14></TD>
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    <TD>&nbsp;</TD>
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