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Challenges Decode periodic decimal fractions

Rational numbers in decimal representation can have an infinite periodic part. One common way to write this down is to repeat the periodic digits and then add three dots. Numbers without those thre...

2 answers · posted 3y ago by celtschk‭ · edited 3y ago by General Sebast1an‭

Question code-golf number parsing

#3: Post edited by

General Sebast1an‭ · 2021-09-25T11:31:36Z (about 3 years ago)

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Decode periodic decimal fractions

Rational numbers in decimal representation can have an infinite periodic part. One common way to write this down is to repeat the periodic digits and then add three dots. Numbers without those three dots are taken to be non-periodic (or equivalently, have a periodic `0` after the given digits). Your task is to decode this representation into a fully cancelled fraction.
In particular, the numbers to decode are given as follows:
* There is an optional sign (+ or -). If omitted, + is assumed.
* There is an integral part. If empty, it is taken
to be 0.
* There is a decimal point, which is optional if the number
is an integer and the integral part was not omitted.
* There is an fractional part following the integer.
* If the fractional part has at least one digit, it may be
followed by three dots.
The program shall take a string as input, and give a fully cancelled fraction (as pair numerator/denominator) as result. It may assume that the given string conforms to the number format.
The string has to be interpreted as follows:
* If the string does not end in three dots, it is interpreted
as exact number.
* If the string does end in three dots, find the longest
repeating digit sequence in the fractional part preceding
the three dots. If no such repeating sequence is found,
the period consists of just the last digit. Otherwise
it consists of that longest repeating digit sequence.
* Output the fraction that corresponds to the determined
periodic digit sequence. The denominator shall be
positive. The fraction shall be completely cancelled.
* Your code must handle at least up to 6 digits before and
up to 6 digits after the decimal point.
~~This is code golf, that is the shortest code wins.~~
Test cases:
```
"0" -> 0/1
"-0" -> 0/1
"+0.0" -> 0/1
"42" -> 42/1
"+2" -> 2/1
"-6" -> -6/1
"-2.0" -> -2/1
"0815" -> 815/1
"." -> 0/1
"+." -> 0/1
"-." -> 0/1
".0" -> 0/1
"+00.0" -> 0/1
"-.2" -> -1/5
"3.14" -> 157/50
".3..." -> 1/3
"+.11..." -> 1/9
"1.0..." -> 1/1
"2.9..." -> 3/1
"0.121..." -> 109/900
"0.1212..." -> 4/33
"0.12121..." -> 4/33
"0.12122..." -> 1091/9000
".122122..." -> 122/999
".022122..." -> 1991/90000
".0221221..." -> 221/9990
"-123456.123434..." -> -611107811/4950
```

Rational numbers in decimal representation can have an infinite periodic part. One common way to write this down is to repeat the periodic digits and then add three dots. Numbers without those three dots are taken to be non-periodic (or equivalently, have a periodic `0` after the given digits). Your task is to decode this representation into a fully cancelled fraction.
In particular, the numbers to decode are given as follows:
* There is an optional sign (+ or -). If omitted, + is assumed.
* There is an integral part. If empty, it is taken
to be 0.
* There is a decimal point, which is optional if the number
is an integer and the integral part was not omitted.
* There is an fractional part following the integer.
* If the fractional part has at least one digit, it may be
followed by three dots.
The program shall take a string as input, and give a fully cancelled fraction (as pair numerator/denominator) as result. It may assume that the given string conforms to the number format.
The string has to be interpreted as follows:
* If the string does not end in three dots, it is interpreted
as exact number.
* If the string does end in three dots, find the longest
repeating digit sequence in the fractional part preceding
the three dots. If no such repeating sequence is found,
the period consists of just the last digit. Otherwise
it consists of that longest repeating digit sequence.
* Output the fraction that corresponds to the determined
periodic digit sequence. The denominator shall be
positive. The fraction shall be completely cancelled.
* Your code must handle at least up to 6 digits before and
up to 6 digits after the decimal point.
This is <a class="badge is-tag">code-golf</a>, that is the shortest code wins.
Test cases:
```
"0" -> 0/1
"-0" -> 0/1
"+0.0" -> 0/1
"42" -> 42/1
"+2" -> 2/1
"-6" -> -6/1
"-2.0" -> -2/1
"0815" -> 815/1
"." -> 0/1
"+." -> 0/1
"-." -> 0/1
".0" -> 0/1
"+00.0" -> 0/1
"-.2" -> -1/5
"3.14" -> 157/50
".3..." -> 1/3
"+.11..." -> 1/9
"1.0..." -> 1/1
"2.9..." -> 3/1
"0.121..." -> 109/900
"0.1212..." -> 4/33
"0.12121..." -> 4/33
"0.12122..." -> 1091/9000
".122122..." -> 122/999
".022122..." -> 1991/90000
".0221221..." -> 221/9990
"-123456.123434..." -> -611107811/4950
```

code-golf number parsing

#2: Post edited by

celtschk‭ · 2021-09-15T05:53:36Z (about 3 years ago)
Added forgotten scoring criterion

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Rational numbers in decimal representation can have an infinite periodic part. One common way to write this down is to repeat the periodic digits and then add three dots. Numbers without those three dots are taken to be non-periodic (or equivalently, have a periodic `0` after the given digits). Your task is to decode this representation into a fully cancelled fraction.
In particular, the numbers to decode are given as follows:
* There is an optional sign (+ or -). If omitted, + is assumed.
* There is an integral part. If empty, it is taken
to be 0.
* There is a decimal point, which is optional if the number
is an integer and the integral part was not omitted.
* There is an fractional part following the integer.
* If the fractional part has at least one digit, it may be
followed by three dots.
The program shall take a string as input, and give a fully cancelled fraction (as pair numerator/denominator) as result. It may assume that the given string conforms to the number format.
The string has to be interpreted as follows:
* If the string does not end in three dots, it is interpreted
as exact number.
* If the string does end in three dots, find the longest
repeating digit sequence in the fractional part preceding
the three dots. If no such repeating sequence is found,
the period consists of just the last digit. Otherwise
it consists of that longest repeating digit sequence.
* Output the fraction that corresponds to the determined
periodic digit sequence. The denominator shall be
positive. The fraction shall be completely cancelled.
* Your code must handle at least up to 6 digits before and
up to 6 digits after the decimal point.
Test cases:
```
"0" -> 0/1
"-0" -> 0/1
"+0.0" -> 0/1
"42" -> 42/1
"+2" -> 2/1
"-6" -> -6/1
"-2.0" -> -2/1
"0815" -> 815/1
"." -> 0/1
"+." -> 0/1
"-." -> 0/1
".0" -> 0/1
"+00.0" -> 0/1
"-.2" -> -1/5
"3.14" -> 157/50
".3..." -> 1/3
"+.11..." -> 1/9
"1.0..." -> 1/1
"2.9..." -> 3/1
"0.121..." -> 109/900
"0.1212..." -> 4/33
"0.12121..." -> 4/33
"0.12122..." -> 1091/9000
".122122..." -> 122/999
".022122..." -> 1991/90000
".0221221..." -> 221/9990
"-123456.123434..." -> -611107811/4950
```

Rational numbers in decimal representation can have an infinite periodic part. One common way to write this down is to repeat the periodic digits and then add three dots. Numbers without those three dots are taken to be non-periodic (or equivalently, have a periodic `0` after the given digits). Your task is to decode this representation into a fully cancelled fraction.
In particular, the numbers to decode are given as follows:
* There is an optional sign (+ or -). If omitted, + is assumed.
* There is an integral part. If empty, it is taken
to be 0.
* There is a decimal point, which is optional if the number
is an integer and the integral part was not omitted.
* There is an fractional part following the integer.
* If the fractional part has at least one digit, it may be
followed by three dots.
The program shall take a string as input, and give a fully cancelled fraction (as pair numerator/denominator) as result. It may assume that the given string conforms to the number format.
The string has to be interpreted as follows:
* If the string does not end in three dots, it is interpreted
as exact number.
* If the string does end in three dots, find the longest
repeating digit sequence in the fractional part preceding
the three dots. If no such repeating sequence is found,
the period consists of just the last digit. Otherwise
it consists of that longest repeating digit sequence.
* Output the fraction that corresponds to the determined
periodic digit sequence. The denominator shall be
positive. The fraction shall be completely cancelled.
* Your code must handle at least up to 6 digits before and
up to 6 digits after the decimal point.
This is code golf, that is the shortest code wins.
Test cases:
```
"0" -> 0/1
"-0" -> 0/1
"+0.0" -> 0/1
"42" -> 42/1
"+2" -> 2/1
"-6" -> -6/1
"-2.0" -> -2/1
"0815" -> 815/1
"." -> 0/1
"+." -> 0/1
"-." -> 0/1
".0" -> 0/1
"+00.0" -> 0/1
"-.2" -> -1/5
"3.14" -> 157/50
".3..." -> 1/3
"+.11..." -> 1/9
"1.0..." -> 1/1
"2.9..." -> 3/1
"0.121..." -> 109/900
"0.1212..." -> 4/33
"0.12121..." -> 4/33
"0.12122..." -> 1091/9000
".122122..." -> 122/999
".022122..." -> 1991/90000
".0221221..." -> 221/9990
"-123456.123434..." -> -611107811/4950
```

number parsing

code-golf number parsing

#1: Initial revision by

celtschk‭ · 2021-09-13T16:27:55Z (about 3 years ago)

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Decode periodic decimal fractions

Rational numbers in decimal representation can have an infinite periodic part. One common way to write this down is to repeat the periodic digits and then add three dots. Numbers without those three dots are taken to be non-periodic (or equivalently, have a periodic `0` after the given digits). Your task is to decode this representation into a fully cancelled fraction.

In particular, the numbers to decode are given as follows:

  * There is an optional sign (+ or -). If omitted, + is assumed.

  * There is an integral part. If empty, it is taken
    to be 0.

  * There is a decimal point, which is optional if the number
    is an integer and the integral part was not omitted.

  * There is an fractional part following the integer.

  * If the fractional part has at least one digit, it may be
    followed by three dots.

The program shall take a string as input, and give a fully cancelled fraction (as pair numerator/denominator) as result. It may assume that the given string conforms to the number format.

The string has to be interpreted as follows:

  * If the string does not end in three dots, it is interpreted
    as exact number.

  * If the string does end in three dots, find the longest
    repeating digit sequence in the fractional part preceding
    the three dots. If no such repeating sequence is found,
    the period consists of just the last digit. Otherwise
    it consists of that longest repeating digit sequence.

  * Output the fraction that corresponds to the determined
    periodic digit sequence. The denominator shall be
    positive. The fraction shall be completely cancelled.

  * Your code must handle at least up to 6 digits before and
    up to 6 digits after the decimal point.

Test cases:
```
                "0" -> 0/1
               "-0" -> 0/1
             "+0.0" -> 0/1
               "42" -> 42/1
               "+2" -> 2/1
               "-6" -> -6/1
             "-2.0" -> -2/1
             "0815" -> 815/1
                "." -> 0/1
               "+." -> 0/1
               "-." -> 0/1
               ".0" -> 0/1
            "+00.0" -> 0/1
              "-.2" -> -1/5
             "3.14" -> 157/50
            ".3..." -> 1/3
          "+.11..." -> 1/9
           "1.0..." -> 1/1
           "2.9..." -> 3/1
         "0.121..." -> 109/900
        "0.1212..." -> 4/33
       "0.12121..." -> 4/33
       "0.12122..." -> 1091/9000
       ".122122..." -> 122/999
       ".022122..." -> 1991/90000
      ".0221221..." -> 221/9990
"-123456.123434..." -> -611107811/4950
```

number parsing

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