Price fraction: Difference between revisions
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<lang AutoHotkey>; Submitted by MasterFocus - http://tiny.cc/iTunis |
<lang AutoHotkey>; Submitted by MasterFocus --- http://tiny.cc/iTunis |
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Loop |
Loop |
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Revision as of 17:47, 10 April 2010
You are encouraged to solve this task according to the task description, using any language you may know.
A friend of mine runs a Pharmacy. He has a specialised rounding function in his Dispensary application which receives a decimal value of currency and forces it to a standard value. This value is regulated by a government department.
Task: Given a floating point value between 0.00 and 1.00, rescale according to the following table:
>= 0.00 < 0.06 := 0.10 >= 0.06 < 0.11 := 0.18 >= 0.11 < 0.16 := 0.26 >= 0.16 < 0.21 := 0.32 >= 0.21 < 0.26 := 0.38 >= 0.26 < 0.31 := 0.44 >= 0.31 < 0.36 := 0.50 >= 0.36 < 0.41 := 0.54 >= 0.41 < 0.46 := 0.58 >= 0.46 < 0.51 := 0.62 >= 0.51 < 0.56 := 0.66 >= 0.56 < 0.61 := 0.70 >= 0.61 < 0.66 := 0.74 >= 0.66 < 0.71 := 0.78 >= 0.71 < 0.76 := 0.82 >= 0.76 < 0.81 := 0.86 >= 0.81 < 0.86 := 0.90 >= 0.86 < 0.91 := 0.94 >= 0.91 < 0.96 := 0.98 >= 0.96 < 1.01 := 1.00
AutoHotkey
<lang AutoHotkey>; Submitted by MasterFocus --- http://tiny.cc/iTunis
Loop {
InputBox, OutputVar, Price Fraction Example, Insert the value to be rounded.`n* [ 0 < value < 1 ]`n* Press ESC or Cancel to exit, , 200, 150 If ErrorLevel Break MsgBox % "Input: " OutputVar "`nResult: " PriceFraction( OutputVar )
}
- -----------------------------------------
PriceFraction( p_Input ) {
If p_Input is not float ; returns 0 if input is not a float Return 0
If ( ( p_Input <= 0 ) OR ( p_Input >= 1 ) ) ; returns 0 is input is out of range Return 0
; declaring the table (arbitrary delimiters in use are '§' and '|') l_List := "0.06|0.10§0.11|0.18§0.16|0.26§0.21|0.32§0.26|0.38§0.31|0.44§0.36|0.50§0.41|0.54§0.46|0.58§0.51|0.62§0.56|0.66§0.61|0.70§0.66|0.74§0.71|0.78§0.76|0.82§0.81|0.86§0.86|0.90§0.91|0.94§0.96|0.98§1.01|1.00"
Loop, Parse, l_List, § ; retrieves each field (delimited by '§')
{
StringSplit, l_Array, A_LoopField, | ; splits current field (using delimiter '|')
If ( p_Input <= l_Array1 )
Return l_Array2 ; returns the second value if input <= first value
}
Return 0 ; returns 0, indicating failure (shouldn't be reached though)
}</lang>
BASIC
This could also be done by building an array, but I felt that this was simpler.
<lang qbasic>DECLARE FUNCTION PriceFraction! (price AS SINGLE)
RANDOMIZE TIMER DIM x AS SINGLE x = RND PRINT x, PriceFraction(x)
FUNCTION PriceFraction! (price AS SINGLE)
'returns price unchanged if invalid value
SELECT CASE price
CASE IS < 0!
PriceFraction! = price
CASE IS < .06
PriceFraction! = .1
CASE IS < .11
PriceFraction! = .18
CASE IS < .16
PriceFraction! = .26
CASE IS < .21
PriceFraction! = .32
CASE IS < .26
PriceFraction! = .38
CASE IS < .31
PriceFraction! = .44
CASE IS < .36
PriceFraction! = .5
CASE IS < .41
PriceFraction! = .54
CASE IS < .46
PriceFraction! = .58
CASE IS < .51
PriceFraction! = .62
CASE IS < .56
PriceFraction! = .66
CASE IS < .61
PriceFraction! = .7
CASE IS < .66
PriceFraction! = .74
CASE IS < .71
PriceFraction! = .78
CASE IS < .76
PriceFraction! = .82
CASE IS < .81
PriceFraction! = .86
CASE IS < .86
PriceFraction! = .9
CASE IS < .91
PriceFraction! = .94
CASE IS < .96
PriceFraction! = .98
CASE IS < 1.01
PriceFraction! = 1!
CASE ELSE
PriceFraction! = price
END SELECT
END FUNCTION</lang>
Sample outputs (run 5 times):
.7388727 .82 .8593103 .9 .826687 .9 .3444635 .5 .0491907 .1
C++
<lang C++>#include <iostream>
- include <cmath>
int main( ) {
double froms[ ] = { 0.00 , 0.06 , 0.11 , 0.16 , 0.21 , 0.26 ,
0.31 , 0.36 , 0.41 , 0.46 , 0.51 , 0.56 , 0.61 , 0.66 ,
0.71 , 0.76 , 0.81 , 0.86 , 0.91 , 0.96 } ;
double tos[ ] = { 0.06 , 0.11 , 0.16 , 0.21 , 0.26 , 0.31 ,
0.36 , 0.41 , 0.46 , 0.51 , 0.56 , 0.61 , 0.66 , 0.71 ,
0.76 , 0.81 , 0.86 , 0.91 , 0.96 , 1.01 } ;
double replacements [] = { 0.10 , 0.18 , 0.26 , 0.32 , 0.38 ,
0.44 , 0.50 , 0.54 , 0.58 , 0.62 , 0.66 , 0.70 , 0.74 ,
0.78 , 0.82 , 0.86 , 0.90 , 0.94 , 0.98 , 1.00 } ;
double number = 0.1 ;
std::cout << "Enter a fractional number between 0 and 1 ( 0 to end )!\n" ;
std::cin >> number ;
while ( number != 0 ) {
if ( ( number < 0 ) || ( number > 1 ) ) {
std::cout << "Error! Only positive values between 0 and 1 are allowed!\n" ; return 1 ;
}
double integerpart = floor ( number ) ;
double remainder = number - integerpart ;
int n = 0 ;
while ( ! ( ( remainder >= froms[ n ] ) && ( remainder < tos[ n ] ) ) )
n++ ;
std::cout << "-->" << ( integerpart + replacements[ n ] ) << '\n' ;
std::cout << "Enter a fractional number ( 0 to end )!\n" ;
std::cin >> number ;
}
return 0 ;
} </lang>
Sample output: Enter a fractional number between 0 and 1 ( 0 to end )! 0.7 -->0.78 Enter a fractional number ( 0 to end )! 0.32 -->0.5 Enter a fractional number ( 0 to end )! 0.12 -->0.26 Enter a fractional number ( 0 to end )! 0
Clipper
<lang dbase>FUNCTION PriceFraction( npQuantDispensed )
LOCAL aPriceFraction := { {0,.06,.1},;
{.06,.11,.18}, ;
{.11,.16,.26}, ;
{.16,.21,.32}, ;
{.21,.26,.38}, ;
{.26,.31,.44}, ;
{.31,.36,.5}, ;
{.36,.41,.54}, ;
{.41,.46,.58}, ;
{.46,.51,.62}, ;
{.51,.56,.66}, ;
{.56,.61,.7}, ;
{.61,.66,.74}, ;
{.66,.71,.78}, ;
{.71,.76,.82}, ;
{.76,.81,.86}, ;
{.81,.86,.9}, ;
{.86,.91,.94}, ;
{.91,.96,.98} }
LOCAL nResult
LOCAL nScan
IF npQuantDispensed = 0
nResult = 0
ELSEIF npQuantDispensed >= .96
nResult = 1
ELSE
nScan := ASCAN( aPriceFraction, ;
{ |aItem| npQuantDispensed >= aItem[ 1 ] .AND.;
npQuantDispensed < aItem[ 2 ] } )
nResult := aPriceFraction[ nScan ][ 3 ]
END IF
RETURN nResult</lang>
Fortran
<lang fortran>program price_fraction
implicit none integer, parameter :: i_max = 10 integer :: i real, dimension (20), parameter :: in = & & (/0.00, 0.06, 0.11, 0.16, 0.21, 0.26, 0.31, 0.36, 0.41, 0.46, & & 0.51, 0.56, 0.61, 0.66, 0.71, 0.76, 0.81, 0.86, 0.91, 0.96/) real, dimension (20), parameter :: out = & & (/0.10, 0.18, 0.26, 0.32, 0.38, 0.44, 0.50, 0.54, 0.58, 0.62, & & 0.66, 0.70, 0.74, 0.78, 0.82, 0.86, 0.90, 0.94, 0.98, 1.00/) real :: r
do i = 1, i_max call random_number (r) write (*, '(f8.6, 1x, f4.2)') r, out (maxloc (in, r >= in)) end do
end program price_fraction</lang> Sample output: <lang>0.997560 1.00 0.566825 0.70 0.965915 1.00 0.747928 0.82 0.367391 0.54 0.480637 0.62 0.073754 0.18 0.005355 0.10 0.347081 0.50 0.342244 0.50</lang>
J
Solution: <lang j>le =: -0.96 0.91 0.86 0.81 0.76 0.71 0.66 0.61 0.56 0.51 0.46 0.41 0.36 0.31 0.26 0.21 0.16 0.11 0.06 0.0 out =: 1.00 0.98 0.94 0.90 0.86 0.82 0.78 0.74 0.70 0.66 0.62 0.58 0.54 0.50 0.44 0.38 0.32 0.26 0.18 0.1
priceFraction =: out {~ le I. -</lang>
Example: <lang j> priceFraction 0.34 0.070145 0.06 0.05 0.50214 0.56 1 0.99 0 0.5 0.18 0.18 0.1 0.62 0.7 1 1 0.1</lang>
OCaml
<lang ocaml>let price_fraction v =
if v < 0.0 || v >= 1.01 then
invalid_arg "price_fraction";
let rec aux = function
| (x,r)::tl ->
if v < x then r
else aux tl
| [] -> assert false
in
aux [
0.06, 0.10; 0.11, 0.18; 0.16, 0.26; 0.21, 0.32; 0.26, 0.38;
0.31, 0.44; 0.36, 0.50; 0.41, 0.54; 0.46, 0.58; 0.51, 0.62;
0.56, 0.66; 0.61, 0.70; 0.66, 0.74; 0.71, 0.78; 0.76, 0.82;
0.81, 0.86; 0.86, 0.90; 0.91, 0.94; 0.96, 0.98; 1.01, 1.00;
]</lang>
<lang ocaml>let () =
let ok_tests = [ (0.3793, 0.54); (0.4425, 0.58); (0.0746, 0.18); (0.6918, 0.78); (0.2993, 0.44); (0.5486, 0.66); (0.7848, 0.86); (0.9383, 0.98); (0.2292, 0.38); ] in Printf.printf " input res ok\n"; List.iter (fun (v,ok) -> let r = price_fraction v in Printf.printf " %6g %g %b\n" v r (r = ok); ) ok_tests;
- </lang>
Oz
Using a for-loop with return and a default value for values >= 1.01. For out-of-range input, a "failed value" is returned, i.e. a value that throws an exception when it is accessed.
<lang oz>fun {PriceFraction X}
OutOfRange = {Value.failed outOfRange(X)}
in
for Limit#Result in
[0.00#OutOfRange
0.06#0.10 0.11#0.18 0.16#0.26 0.21#0.32 0.26#0.38 0.31#0.44 0.36#0.5
0.41#0.54 0.46#0.58 0.51#0.62 0.56#0.66 0.61#0.70 0.66#0.74 0.71#0.78
0.76#0.82 0.81#0.86 0.86#0.90 0.91#0.94 0.96#0.98 1.01#1.00
]
return:Return
default:OutOfRange
do
if X < Limit then {Return Result} end
end
end</lang>
PL/I
<lang PL/I> declare t(20) fixed decimal (3,2) static initial (
.06, .11, .16, .21, .26, .31, .36, .41, .46, .51, .56, .61, .66, .71, .76, .81, .86, .91, .96, 1.01);
declare r(20) fixed decimal (3,2) static initial (
.10, .18, .26, .32, .38, .44, .50, .54, .58, .62, .66, .70, .74, .78, .82, .86, .90, .94, .98, 1);
declare x float, d fixed decimal (3,2); declare i fixed binary;
loop:
do i = 1 to 20;
if x < t(i) then
do; d = r(i); leave loop; end;
end;
</lang>
PureBasic
<lang PureBasic>Procedure.f PriceFraction(price.f)
;returns price unchanged if value is invalid
Protected fraction
Select price * 100
Case 0 To 5
fraction = 10
Case 06 To 10
fraction = 18
Case 11 To 15
fraction = 26
Case 16 To 20
fraction = 32
Case 21 To 25
fraction = 38
Case 26 To 30
fraction = 44
Case 31 To 35
fraction = 5
Case 36 To 40
fraction = 54
Case 41 To 45
fraction = 58
Case 46 To 50
fraction = 62
Case 51 To 55
fraction = 66
Case 56 To 60
fraction = 7
Case 61 To 65
fraction = 74
Case 66 To 70
fraction = 78
Case 71 To 75
fraction = 82
Case 76 To 80
fraction = 86
Case 81 To 85
fraction = 9
Case 86 To 90
fraction = 94
Case 91 To 95
fraction = 98
Case 96 To 100
fraction = 100
Default
ProcedureReturn price
EndSelect
ProcedureReturn fraction / 100
EndProcedure
If OpenConsole()
Define x.f, i For i = 1 To 10 x = Random(10000)/10000 PrintN(StrF(x, 4) + " -> " + StrF(PriceFraction(x), 2)) Next Print(#CRLF$ + #CRLF$ + "Press ENTER to exit") Input() CloseConsole()
EndIf</lang> Sample output:
0.3793 -> 0.54 0.4425 -> 0.58 0.0746 -> 0.18 0.6918 -> 0.78 0.2993 -> 0.44 0.5486 -> 0.66 0.7848 -> 0.86 0.9383 -> 0.98 0.2292 -> 0.38 0.9560 -> 1.00
Python
Using the bisect standard module to reduce the comparisons with members of the cin array.
<lang python>>>> import bisect >>> _cin = [.06, .11, .16, .21, .26, .31, .36, .41, .46, .51, .56, .61, .66, .71, .76, .81, .86, .91, .96, 1.01] >>> _cout = [.10, .18, .26, .32, .38, .44, .50, .54, .58, .62, .66, .70, .74, .78, .82, .86, .90, .94, .98, 1.00] >>> def pricerounder(pricein): return _cout[ bisect.bisect_right(_cin, pricein) ]</lang>
When dealing with money it is good to think about possible loss of precision. If we change the units to be integer cents we could use the following exact routine: <lang python>>>> import bisect >>> _cin = [ 6, 11, 16, 21, 26, 31, 36, 41, 46, 51, 56, 61, 66, 71, 76, 81, 86, 91, 96, 101] >>> _cout = [10, 18, 26, 32, 38, 44, 50, 54, 57, 62, 66, 70, 74, 78, 82, 86, 90, 94, 98, 100] >>> def centsrounder(centsin): return _cout[ bisect.bisect_right(_cin, centsin) ]</lang> Other options are to use the fractions or decimals modules for calculating money to a known precision.
Ruby
A simple function with hardcoded values. <lang ruby>def rescale_price_fraction(value)
raise ArgumentError, "value=#{value}, must have: 0 <= value < 1.01" if value < 0 || value >= 1.01
if value < 0.06 then 0.10
elsif value < 0.11 then 0.18
elsif value < 0.16 then 0.26
elsif value < 0.21 then 0.32
elsif value < 0.26 then 0.38
elsif value < 0.31 then 0.44
elsif value < 0.36 then 0.50
elsif value < 0.41 then 0.54
elsif value < 0.46 then 0.58
elsif value < 0.51 then 0.62
elsif value < 0.56 then 0.66
elsif value < 0.61 then 0.70
elsif value < 0.66 then 0.74
elsif value < 0.71 then 0.78
elsif value < 0.76 then 0.82
elsif value < 0.81 then 0.86
elsif value < 0.86 then 0.90
elsif value < 0.91 then 0.94
elsif value < 0.96 then 0.98
elsif value < 1.01 then 1.00
end
end</lang>
Or, where we can cut and paste the textual table in one place
for the String#lines method.
For Ruby 1.8.6, use String#each_line
<lang ruby>class Price
ConversionTable = <<-END_OF_TABLE >= 0.00 < 0.06 := 0.10 >= 0.06 < 0.11 := 0.18 >= 0.11 < 0.16 := 0.26 >= 0.16 < 0.21 := 0.32 >= 0.21 < 0.26 := 0.38 >= 0.26 < 0.31 := 0.44 >= 0.31 < 0.36 := 0.50 >= 0.36 < 0.41 := 0.54 >= 0.41 < 0.46 := 0.58 >= 0.46 < 0.51 := 0.62 >= 0.51 < 0.56 := 0.66 >= 0.56 < 0.61 := 0.70 >= 0.61 < 0.66 := 0.74 >= 0.66 < 0.71 := 0.78 >= 0.71 < 0.76 := 0.82 >= 0.76 < 0.81 := 0.86 >= 0.81 < 0.86 := 0.90 >= 0.86 < 0.91 := 0.94 >= 0.91 < 0.96 := 0.98 >= 0.96 < 1.01 := 1.00 END_OF_TABLE
@@conversion_table = ConversionTable.lines.collect do |line|
line.scan(/\d\.\d\d/).collect {|str| str.to_f}
end
MIN = @@conversion_table[0][0] MAX = @@conversion_table[-1][1]
def initialize(value)
if value < MIN || value >= MAX
raise ArgumentError, "value=#{value}, must have: #{MIN} <= value < #{MAX}"
end
@standard_value = (@@conversion_table.find do |lower, upper, standard|
value.between?(lower, upper)
end)[2]
end
attr_reader :standard_value
end</lang>
And a test suite <lang ruby>require 'test/unit'
class PriceFractionTests < Test::Unit::TestCase
@@ok_tests = [ [0.3793, 0.54], [0.4425, 0.58], [0.0746, 0.18], [0.6918, 0.78], [0.2993, 0.44], [0.5486, 0.66], [0.7848, 0.86], [0.9383, 0.98], [0.2292, 0.38], ] @@bad_tests = [1.02, -3]
def test_ok
@@ok_tests.each do |val, exp|
assert_equal(exp, rescale_price_fraction(val))
assert_equal(exp, Price.new(val).standard_value)
end
@@bad_tests.each do |val|
assert_raise(ArgumentError) {rescale_price_fraction(val)}
assert_raise(ArgumentError) {Price.new(val).standard_value}
end
end
# demonstrate why it's bad to use floats for money # 0.06 should map to 0.18, but the floating point representation of 0.06 is # slightly less, so the conversion returns 0.10 instead def test_uhoh assert_equal(0.18, Price.new(0.06).standard_value) end
end</lang>
output
Loaded suite price_fraction Started .F Finished in 0.018000 seconds. 1) Failure: test_uhoh(PriceFractionTests) [price_fraction.rb:119]: <0.18> expected but was <0.1>. 2 tests, 23 assertions, 1 failures, 0 errors, 0 skips
Tcl
Structured as two functions, one to parse the input data as described in the problem into a form which Tcl can work with easily, and the other to perform the mapping. <lang tcl># Used once to turn the table into a "nice" form proc parseTable table {
set map {}
set LINE_RE {^ *>= *([0-9.]+) *< *([0-9.]+) *:= *([0-9.]+) *$}
foreach line [split $table \n] {
if {[string trim $line] eq ""} continue if {[regexp $LINE_RE $line -> min max target]} { lappend map $min $max $target } else { error "invalid table format: $line" }
} return $map
}
- How to apply the "nice" table to a particular value
proc priceFraction {map value} {
foreach {minimum maximum target} $map {
if {$value >= $minimum && $value < $maximum} {return $target}
} # Failed to map; return the input return $value
}</lang> How it is used: <lang tcl># Make the mapping set inputTable {
>= 0.00 < 0.06 := 0.10 >= 0.06 < 0.11 := 0.18 >= 0.11 < 0.16 := 0.26 >= 0.16 < 0.21 := 0.32 >= 0.21 < 0.26 := 0.38 >= 0.26 < 0.31 := 0.44 >= 0.31 < 0.36 := 0.50 >= 0.36 < 0.41 := 0.54 >= 0.41 < 0.46 := 0.58 >= 0.46 < 0.51 := 0.62 >= 0.51 < 0.56 := 0.66 >= 0.56 < 0.61 := 0.70 >= 0.61 < 0.66 := 0.74 >= 0.66 < 0.71 := 0.78 >= 0.71 < 0.76 := 0.82 >= 0.76 < 0.81 := 0.86 >= 0.81 < 0.86 := 0.90 >= 0.86 < 0.91 := 0.94 >= 0.91 < 0.96 := 0.98 >= 0.96 < 1.01 := 1.00
} set map [parseTable $inputTable]
- Apply the mapping to some inputs (from the Oz example)
foreach example {.7388727 .8593103 .826687 .3444635 .0491907} {
puts "$example -> [priceFraction $map $example]"
}</lang> Output:
.7388727 -> 0.82 .8593103 -> 0.90 .826687 -> 0.90 .3444635 -> 0.50 .0491907 -> 0.10
Ursala
<lang Ursala>#import flo
le = <0.06,.11,.16,.21,.26,.31,.36,.41,.46,.51,.56,.61,.66,.71,.76,.81,.86,.91,.96,1.01> out = <0.10,.18,.26,.32,.38,.44,.50,.54,.58,.62,.66,.70,.74,.78,.82,.86,.90,.94,.98,1.>
price_fraction = fleq@rlPlX*|rhr\~&p(le,out)</lang> main points:
~&p(le,out)zips the pair of listsleandoutinto a list of pairs- A function of the form
f\yapplied to an argumentxevaluates tof(x,y) - A function of the form
f*|applied to a pair(x,y)whereyis a list, makes a list of pairs withxon the left of each item and an item ofyon the right. Then it appliesfto each pair, makes a list of the right sides of those for whichfreturned true, and makes a separate list of the right sides of those for whichfreturned false. - The suffix
rhrafter the*|operator extracts the right side of the head of the right list from the result. - The operand to the
*|operator,fleq@rlPlXis the less-or-equal predicate on floating point numbers, composed with the function~&rlPlXwhich transforms a triple(u,(v,w))to(v,u)
test program: <lang Ursala>#cast %eL
test = price_fraction* <0.34,0.070145,0.06,0.05,0.50214,0.56,1.,0.99,0.> </lang> output:
< 5.000000e-01, 1.800000e-01, 1.800000e-01, 1.000000e-01, 6.200000e-01, 7.000000e-01, 1.000000e+00, 1.000000e+00, 1.000000e-01>