Ruby – How to convert only strings hash values that are numbers to integers

integerrubystringtype conversion

I have rows of hashes imported from several different XML database dumps that look like this (but with varying keys):

{"Id"=>"1", "Name"=>"Cat", "Description"=>"Feline", "Count"=>"123"}

I tried using #to_i but it converts a non-number string to 0:

"Feline".to_i
# => 0

But what I'd like is a way for "Feline" to remain a string, while Id and Count in the above example become integers 1 and 123.

Is there an easy way to convert only the strings values that are numbers into integers?

Best Answer

One line answer: Using regex approach

h.merge(h) { |k, v| v.match(/\A[+-]?\d+?(\.\d+)?\Z/) ? v.to_i : v }

Using Integer approach

h.merge(h) { |k, v| Integer(v) rescue v }

Related Solutions

Python – How to convert strings into integers

int() is the Python standard built-in function to convert a string into an integer value. You call it with a string containing a number as the argument, and it returns the number converted to an integer:

>>> int("1") + 1
2

If you know the structure of your list, T1 (that it simply contains lists, only one level), you could do this in Python 3:

T2 = [list(map(int, x)) for x in T1]

In Python 2:

T2 = [map(int, x) for x in T1]

Python – Checking if a string can be converted to float in Python

I would just use..

try:
    float(element)
except ValueError:
    print "Not a float"

..it's simple, and it works. Note that it will still throw OverflowError if element is e.g. 1<<1024.

Another option would be a regular expression:

import re
if re.match(r'^-?\d+(?:\.\d+)$', element) is None:
    print "Not float"

Best Answer

Related Solutions

Python – How to convert strings into integers

Python – Checking if a string can be converted to float in Python

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