Difference: PrintingInAMPL (4 vs. 5)

Revision 52008-03-04 - MichaelOSullivan

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META TOPICPARENT name="AMPLSyntax"
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Displaying Information

You have already seen how to display a variable using the {\tt display} command. We can also display {a href="Expressioins in AMPL">AMPL expressions the same way, e.g., we might want to see how supply we are using in a transportation problem.

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Displaying Information

 
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Often when we display something (like variable values) many of the resulting numbers are 0 and we are only interested in the non-zero numbers. To stop any rows of zeros being displayed you can set the {\tt omit_zero_rows} option:

\begin{verbatim}

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You have already seen how to display a variable using the display command. We can also display AMPL expressions the same way, e.g., we might want to see how supply we are using in a transportation problem.

src="display.jpg"

Often when we display something (like variable values) many of the resulting numbers are 0 and we are only interested in the non-zero numbers. To stop any rows of zeros being displayed you can set the omit_zero_rows option:


 option omit_zero_rows 1;
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\end{verbatim}

To stop any columns of zeros being displayed you can set the {\tt omit_zero_cols} option:

\begin{verbatim}

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To stop any columns of zeros being displayed you can set the omit_zero_cols option:

 option omit_zero_cols 1;
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\end{verbatim}

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src="omit.jpg"

You can also force display to use either tables or a single column by using the display_1col option. This option will use one column if the number of values to display is less than display_1col. The initial value of display_1col is 20, so any display command that shows less than 20 values will be displayed as a column. Setting display_1col to 0 forces display to use tables whenever possible.

src="display_1col.jpg"

Printing Information

By playing with the display options we can get the display command to format output in a nice way. However, we can also decide exactly what is displayed by using print and printf.

 
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You can also force {\tt display} to use either tables or a single column by using the {\tt display_1col} option. This option will use one column if the number of values to display is less than {\tt display_1col}. The initial value of {\tt display_1col} is 20, so any {\tt display} command that shows less than 20 values will be displayed as a column. Setting {\tt display_1col} to 0 forces {\tt display} to use tables whenever possible.

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src="print.jpg"
 
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Printing Information

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The print command only writes strings to the output.
 
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By playing with the {\tt display} options we can get the {\tt display} command to format output in a nice way. However, we can also decide exactly what is displayed by using {\tt print} and {\tt printf}. <p

The {\tt print} command only writes strings to the output.

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The printf command allows you to print text and values together in a format you can control. It uses the same printf format as C and Matlab.
 
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The {\tt printf} command allows you to print text and values together in a format you can control. It uses the same {\tt printf} format as C and Matlab.

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src="printf.jpg"
 
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You can print over sets or set expressions as well

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You can print over sets or set expressions as well
 
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Printing to a File

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src="printf_set.jpg"
 
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All the output commands can be directed to a file. Adding {\tt > <filename>} to the end of an output command creates the file with the given name and writes to it. Subsequent output commands append output to the file by adding {\tt >> <filename>} to the commands. You should close your file when done so you can open it with another program. This is very useful for saving your solutions (in a useful format with {\tt printf}), for example

brewery.run

\begin{verbatim}

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Printing to a File

All the output commands can be directed to a file. Adding > <filename&gt to the end of an output command creates the file with the given name and writes to it. Subsequent output commands append output to the file by adding >> <filename> to the commands. You should close your file when done so you can open it with another program. This is very useful for saving your solutions (in a useful format with printf), for example


 # brewery.run reset;
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  solve;
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print 'TRANSPORTATION SOLUTION -- Non-zero shipments' > brewery.out;
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print 'TRANSPORTATION SOLUTION -- Non-zero shipments' > brewery.out;
  display TotalCost >> brewery.out;
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  Flow[s, d], s, d >> brewery.out;

close brewery.out;

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\end{verbatim}

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Running {\tt brewery.run} in AMPL creates a file brewery.out.
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Running brewery.run in AMPL creates a file brewery.out.
  -- MichaelOSullivan - 02 Mar 2008
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  • display.jpg:
    display.jpg

  • omit.jpg:
    omit.jpg

  • display_1col.jpg:
    display_1col.jpg

  • print.jpg:
    print.jpg

  • printf.jpg:
    printf.jpg

  • printf_set.jpg:
    printf_set.jpg

 
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META FILEATTACHMENT attachment="brewery.out" attr="" comment="" date="1204604566" name="brewery.out" path="brewery.out" size="374" stream="brewery.out" tmpFilename="" user="MichaelOSullivan" version="1"
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