Need help converting Perl to Ruby (detecting integers and de


#1

I am trying to convert a Perl script to Ruby and have been having some
difficulty along the way (mostly because I don’t know Perl).

I am currently stumped on one particular line in the old Perl script:

foreach (@rawfields) {if ($_ > 0){$_ = int($_*100)/100}}

Background context: @rawfields is an array that holds the contents of
an imported line from a text file. Here are some sample lines from
the input file:

“0” “0” “0” “0” “0” “0” “Bar”
“5.66666” “0” “3.566662” “1.383332” “6” “0” “Foo”

My guess is that the Perl line iterates through each of the elements
in the array and rounds any integers to 2 decimals.

This raises a few problems for me.

  1. How can I easily tell if the (string) value in each array element
    is an integer or has a decimal value?

=> The desired output for text file line 2 is :

“5.67” “0” “3.57” “1.38” “6” “0” “Foo”

I tried the following in Ruby:

@rawfields.each_index do |x|
if ( @rawfields[x].to_f > 0 )
@rawfields[x] = ( (( @rawfields[x].to_f * 100 ).round.to_i ).to_f /
100 ).to_s
end
end

But it produces the following output:

“5.67” “0” “3.57” “1.38” “6.0” “0” “Foo”

…which is close, but not quite what I want. My output file now has
values like 1.0, 5.0, 62.0, etc. If it’s an integer, I don’t want to
see the decimal.

Can anyone suggest an improvement to my code or a better translation
from Perl?

TIA. Paul.


#2

On 15.03.2007 22:39, Paul wrote:

the input file:

  1. How can I easily tell if the (string) value in each array element
    @rawfields.each_index do |x|

…which is close, but not quite what I want. My output file now has
values like 1.0, 5.0, 62.0, etc. If it’s an integer, I don’t want to
see the decimal.

Can anyone suggest an improvement to my code or a better translation
from Perl?

TIA. Paul.

How about

irb(main):005:0> fields = %w{5.6666 0 Foo}
=> [“5.6666”, “0”, “Foo”]
irb(main):006:0> fields.map {|v| sprintf("%4.2f", Float(v)) rescue v}
=> [“5.67”, “0.00”, “Foo”]

This uses the fact that Float() will throw if the string is not a valid
number. If you really need “0” instead of “0.00” you could apply
another test. If you need the quotes you could do

irb(main):008:0> puts fields.map {|v| (sprintf("%4.2f", Float(v)) rescue
v).inspect}.join(" ")
“5.67” “0.00” “Foo”

Kind regards

robert


#3

On 3/16/07, Paul removed_email_address@domain.invalid wrote:

Background context: @rawfields is an array that holds the contents of
an imported line from a text file. Here are some sample lines from
the input file:

“0” “0” “0” “0” “0” “0” “Bar”
“5.66666” “0” “3.566662” “1.383332” “6” “0” “Foo”

rawfields = [“5.66666”, “0”, “3.566662”, “1.383332”, “6”, “0”, “Foo”]
=> [“5.66666”, “0”, “3.566662”, “1.383332”, “6”, “0”, “Foo”]

rawfields.map {|field| “%0.2f” % Float(field) rescue field}
=> [“5.67”, “0.00”, “3.57”, “1.38”, “6.00”, “0.00”, “Foo”]

Breaking it up,

Float(string) either converts a string to a float, or raises an
exception if it cannot be so converted.

% is the sprintf operator, so “%0.2f” % float rounds the float to two
decimal places and interpolates it into the string. Note that it does
round properly, as per the printf spec, rather than truncating.

finally, expression1 rescue expression2 means return expression1,
unless it raises an exception in which case return expression2

martin


#4

On 3/16/07, Martin DeMello removed_email_address@domain.invalid wrote:

=> [“5.66666”, “0”, “3.566662”, “1.383332”, “6”, “0”, “Foo”]

rawfields.map {|field| “%0.2f” % Float(field) rescue field}
=> [“5.67”, “0.00”, “3.57”, “1.38”, “6.00”, “0.00”, “Foo”]

oops - missed the fact that you didn’t want integers converted into
decimals. Best way I can think of is a two level try/rescue-try/rescue

rawfields.map {|field| “%d” % Integer(field) rescue “%0.2f” %
Float(field) rescue field}
=> [“5.67”, “0”, “3.57”, “1.38”, “6”, “0”, “Foo”]

More explicitly

rawfields.map do |field|
begin
“%d” % Integer(field)
rescue
begin
“%0.2f” % Float(field)
rescue
field
end
end
end

martin


#5

Hi –

On 3/15/07, Paul removed_email_address@domain.invalid wrote:

the input file:

  1. How can I easily tell if the (string) value in each array element
    @rawfields.each_index do |x|

…which is close, but not quite what I want. My output file now has
values like 1.0, 5.0, 62.0, etc. If it’s an integer, I don’t want to
see the decimal.

Can anyone suggest an improvement to my code or a better translation
from Perl?

See if this helps:

@rawfields.map! do |x|
if x =~ /^\d+.\d+$/
“%.2f” % x
else
x
end
end

David


#6

rawfields.map { |f| f.to_f.to_s == f ? “%0.2f” % f.to_f : f }
=> [“5.67”, “0”, “3.57”, “1.38”, “6”, “0”, “Foo”]


#7

That is brilliant! Thank you, Jon! Of all the good suggestions
posted, I like this one best. You guys all rock! Thanks so much for
the responses.

Cheers! Paul. =)


#8

On 3/16/07, Paul removed_email_address@domain.invalid wrote:

That is brilliant! Thank you, Jon! Of all the good suggestions
posted, I like this one best. You guys all rock! Thanks so much for
the responses.

Cheers! Paul. =)

On Mar 15, 6:22 pm, Jon G. wrote:

rawfields.map { |f| f.to_f.to_s == f ? “%0.2f” % f.to_f : f }

rawfields.map{|f| Integer(f) rescue Float(f) rescue f}


#9

Hi –

On 3/15/07, Michael F. removed_email_address@domain.invalid wrote:

rawfields.map{|f| Integer(f) rescue Float(f) rescue f}

That doesn’t produce the desired output.

David