How to convert string into number

ruby-talk
1

Hi all,

I read several rows of numbers and split each row into an array. I get
an array of array. By default Ruby treat each number as a string. I want
to convert each string into a number. The only way I can think of is to
loop through the old array of array, change each element in each row
using #to_f and put them back into a new array. It is not efficient.
What other options might be better?

Thanks,

Li

# file format

1 100 33 32
2 500 33 20

....

···

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Posted via http://www.ruby-forum.com/.

2

Hi,

i would do it like this:

array =

yourfile.each_line{|line| array << line.split(' ').collect(|item| item.to_f)}

Cheers
detlef

···

Am Freitag, den 06.07.2007, 07:36 +0900 schrieb Guest:

Hi all,

I read several rows of numbers and split each row into an array. I get
an array of array. By default Ruby treat each number as a string. I want
to convert each string into a number. The only way I can think of is to
loop through the old array of array, change each element in each row
using #to_f and put them back into a new array. It is not efficient.
What other options might be better?

Thanks,

Li

# file format

1 100 33 32
2 500 33 20

....

3

I read several rows of numbers and split each row into an array. I get
an array of array. By default Ruby treat each number as a string. I want
to convert each string into a number. The only way I can think of is to
loop through the old array of array, change each element in each row
using #to_f and put them back into a new array. It is not efficient.
What other options might be better?

Thanks,

Li

# file format

1 100 33 32
2 500 33 20

One way would be to use #map:

irb(main):013:0> rows = [["1", "100", "33", "32"], ["2", "500", "33", "20"]]
=> [["1", "100", "33", "32"], ["2", "500", "33", "20"]]

irb(main):014:0> rows.each {|row| row.map! {|c| c.to_f} }
=> [[1.0, 100.0, 33.0, 32.0], [2.0, 500.0, 33.0, 20.0]]

You could also use #to_i if you wanted integers.

Hope this helps,

Bill

···

From: "Guest" <chen_li3@yahoo.com>

4

Hi --

Hi all,

I read several rows of numbers and split each row into an array. I get
an array of array. By default Ruby treat each number as a string. I want
to convert each string into a number. The only way I can think of is to
loop through the old array of array, change each element in each row
using #to_f and put them back into a new array. It is not efficient.
What other options might be better?

Thanks,

Li

# file format

1 100 33 32
2 500 33 20

You could do:

require 'scanf'
File.open("filename") do |fh|
   fh.scanf("%f%f%f%f") {|n| n }
end

The point of the {|n| n} is to force a capture of each set of numbers,
using the block form of scanf. If you're not sure how many numbers
are on each line, you'd have to do a little more work but scanf might
still be a good option.

David

···

On Fri, 6 Jul 2007, Guest wrote:

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