# 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

\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:

• omit.jpg:

• display_1col.jpg:

• print.jpg:

• printf.jpg:

• printf_set.jpg:

 META FILEATTACHMENT attachment="four_dp.jpg" attr="h" comment="" date="1204604433" name="four_dp.jpg" path="four_dp.jpg" size="35091" stream="four_dp.jpg" tmpFilename="" user="MichaelOSullivan" version="1" attachment="five_dp.jpg" attr="h" comment="" date="1204604447" name="five_dp.jpg" path="five_dp.jpg" size="36558" stream="five_dp.jpg" tmpFilename="" user="MichaelOSullivan" version="1"
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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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 META FILEATTACHMENT attachment="display.jpg" attr="h" comment="" date="1204605023" name="display.jpg" path="display.jpg" size="43546" stream="display.jpg" tmpFilename="" user="MichaelOSullivan" version="1" attachment="omit.jpg" attr="h" comment="" date="1204605041" name="omit.jpg" path="omit.jpg" size="20893" stream="omit.jpg" tmpFilename="" user="MichaelOSullivan" version="1" attachment="display_1col.jpg" attr="h" comment="" date="1204605073" name="display_1col.jpg" path="display_1col.jpg" size="23462" stream="display_1col.jpg" tmpFilename="" user="MichaelOSullivan" version="1" attachment="print.jpg" attr="h" comment="" date="1204605128" name="print.jpg" path="print.jpg" size="19738" stream="print.jpg" tmpFilename="" user="MichaelOSullivan" version="1" attachment="printf.jpg" attr="h" comment="" date="1204605145" name="printf.jpg" path="printf.jpg" size="49225" stream="printf.jpg" tmpFilename="" user="MichaelOSullivan" version="1" attachment="printf_set.jpg" attr="h" comment="" date="1204605157" name="printf_set.jpg" path="printf_set.jpg" size="54976" stream="printf_set.jpg" tmpFilename="" user="MichaelOSullivan" version="1"

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