Software Salariman

More ways to extract a block of text from a stream and prepend the line number to each line.

Below is the Gawk version. The built-in variables NR is the number of the current line and $0 is the content of the current line.

gawk "(NR >= r1 && NR <= r2) {printf("""%4d %s\n""", NR, $0)}"

The Perl and Ruby scripts are exactly the same. The built-in variable $. holds the number of the current line and $_ holds the text of the current line.

perl|ruby -ne "printf '%4d %s', $., $_ if $. >= r1 && $. <= r2"

The Groovy command line options are similar to the Perl and Ruby version, except that you have to separate -n and -e. The built-in variable count hods the number of the current line and line holds the text of the current line.

groovy -n -e "if (count >= r1 && count <= r2) out.format '%4d %s\n', count, line"

The Python version is verbose due to boilerplate code to iterate through all rows in a file:

python -c "import sys; print ''.join('%4d %s' % (r, l) for r, l in enumerate(sys.stdin) if r >= r1 and r <= r2)"

See Also

• PowerShell and Cat Extract Lines with Line Numbers

PS

2008-07-29: Added Groovy version.

Labels: Gawk, Groovy, Perl, Python, Ruby

link posted by Kam-Hung Soh @ 9:39 AM   0 comments
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Groovy is scripting language on the Java platform. Groovy is interesting because it can be compiled into Java byte-code and makes heavy use of closures.

Groovy Hello World

In the beginning, I ported my Jython version into Groovy. It looks pretty much the same as the Jython version:

// Hello World in Groovy
f = new javax.swing.JFrame("Hello World")
f.setSize(170,70)
f.contentPane.layout = new java.awt.FlowLayout()
f.defaultCloseOperation = javax.swing.JFrame.EXIT_ON_CLOSE
f.add(new javax.swing.JLabel("Label me:"))
f.add(new javax.swing.JButton("Press me"))
f.show()

Groovy + SwingBuilder Hello World

Groovy has a helper class called SwingBuilder to make it much easier to write Swing applications. Here's one way to re-write the program:

// Hello World Window in Groovy + SwingBuilder
sb = new groovy.swing.SwingBuilder()
f = sb.frame(
  title:"Hello World"
  ,size:[170,70]
  ,defaultCloseOperation: javax.swing.JFrame.EXIT_ON_CLOSE) {
  flowLayout()
  label(text:"Label me:")
  button(text:"Press me")
}
f.show()

SwingBuilder is quite wonderful because it allows you to define a GUI with a minimum of code noise. The definition of a JFrame probably maps a keyword X to a setX() function but I haven't worked out how SwingBuilder converts words such as flowLayout(), label and button to Swing objects and functions.

Labels: Groovy, Java

link posted by Kam-Hung Soh @ 6:53 PM   0 comments
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