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Brian_Alexander
Asked: 2020-05-11 05:21:17 +0800 CST 2020-05-11 05:21:17 +0800 CST

How do I add a column from a table to an array in Ruby?

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I have the following file .txt, which I opened with File.Open("productos.txt", "r").

The thing is that this file comes in the following format.

Producto1, 10, 15, 21
Producto2, 20, 0, 3
Producto3, 4, 8, 0
Producto8, 1, 2, NR
Producto12, NR, 2, NR

And I have to add the numbers of the first column, it is also complicated for me since the last number of the column is a string and I have to transform it.

In short, I have to do that sum from column , and I can't find a way to do that separation or get to that position .

ruby

1 Answers

  1. Best Answer

    Considering that the file is not very big (as in your example), I would do the following:

    • Read the entire content of the file
    • Create an array with each line
    • Create an array for each line with the values
    • Convert the values ​​of the first column to number and add them

    In code it would look like this:

    File.read("productos.txt")
    .map(&:strip)
    .sum { |producto| producto.split(",")[1].to_i }
#=> 35

    In case the file is very large, you could choose to use File.foreachinstead of File.readto read the file line by line; for instance:

    File.foreach("productos.txt").sum { |producto| producto.split(",")[1].to_i }
#=> 35

    It is important to note that when applying to_ito a string that does not start with a number , the result is always0 .

    Examples:

    "10".to_i    #=> 10
"NR".to_i    #=> 0
"NR10".to_i  #=> 0
"10NR".to_i  #=> 10
"01NR".to_i  #=> 1
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