units-of-measurement | 易学教程

Maintaining Units of measure across type converstions

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问题 If we define a unit of measure like: [<Measure>] type s and then an integer with a measure let t = 1<s> and then convert it to a float let r = float t we see that r = 1.0 without a measure type. This seems very odd, as all the measure information has been lost. You can use LanguagePrimitives.FloatWithMeasure to convert back to a float with something like let inline floatMeasure (arg:int<'t>) : (float<'t>) = LanguagePrimitives.FloatWithMeasure (float arg) which enforces the right types, but

Converting unit abbreviations to numbers

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I have a dataset that abbreviates numerical values in a column. For example, 12M mean 12 million, 1.2k means 1,200. M and k are the only abbreviations. How can I write code that allows R to sort these values from lowest to highest? I've though about using gsub to convert M to 000,000 etc but that does not take into account the decimals (1.5M would then be 1.5000000). So you want to translate SI unit abbreviations ('K','M',...) into exponents, and thus numerical powers-of-ten. Given that all units are single-letter, and the exponents are uniformly-spaced powers of 10**3, here's working code

Setting medium and long measurement symbols in Swift 3

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问题 In Swift when I create custom units I can only define one symbol. With the built in units there can be short, medium and long units. How do you set the other unit styles for a custom unit? extension UnitEnergy { static let footPounds = UnitEnergy(symbol: "ft-lbs", converter: UnitConverterLinear(coefficient: 1)) } var test = Measurement<UnitEnergy>( value: 10, unit: .footPounds) var formatter = MeasurementFormatter() formatter.locale = Locale(identifier: "es") formatter.unitStyle = .short

Fractional power of units of measures in F#

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Is it true to say that : there are no fractional power units in F# Tomas Petricek In addition to what has already been said, the best resource for information about (not just) F# units of measure is Andrew Kennedy's PhD thesis , who actually designed F# units. He mentions fractional units: The most important decision is whether or not to allow fractional exponents of dimensions. The argument against them is philosophical: a quantity with a dimension such as M 1/2 makes no sense physically, and if such a thing arose, it would suggest revision of the set of base dimensions rather than a re

F# operator overloading for conversion of multiple different units of measure

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I want to be able to do this: let duration = 1<hours> + 2<minutes> + 3<seconds> with the following types and functions (and possibly more units of measure): type [<Measure>] seconds type [<Measure>] minutes type [<Measure>] hours let seconds_per_minute = 60<seconds> / 1<minutes> let minutes_per_hour = 60<minutes> / 1<hours> let minutes_to_seconds minutes seconds = minutes * seconds_per_minute + seconds let hours_to_minutes hours minutes = hours * minutes_per_hour + minutes So basically "hours_to_minutes" should be used for adding hours and minutes, and "minutes_to_seconds" should be used for

How to convert DLU into pixels?

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问题 Microsoft uses dialog length units (DLU) in their guidelines for UI. How can I convert them into pixels? As I know, DLU depending on system font size. Can you advise some simple method of such conversion in Delphi for Win32? 回答1: You should use the MapDialogRect() function. Pass in a RECT in dialog units, and the equivalent RECT in pixel units is returned. Note that you need a handle to a dialog in order to give MapDialogRect() sufficient context. The function needs to know the font in order

Is there any available API to represent various units of item like KG, Litre, Metre, KM, etc

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In my project, somewhere I have to work with a unitOfIssue of Items . Now, various items of course can have different units of representation. So, I was searching for some API or some way, to elegantly handle this situation. Is there any available API, that provides some way to represent these units? I've heard of JScience which seems impressive, but again I am facing another problem with mapping it in JPA . After some google work, I found out that some work is going on in this context as - JScience-JPA , but it seems like it is not yet stable to be used in production. I also found something

SQL Server units question

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问题 This may be a really dumb question, but... What units does Geography.STLength return? The official MSDN page doesn't say anything about the units returned, and this blog entry here says STLength() returns a float indicating the length of the instance in units . Yes, that's right, it says it returns it in units . Can anyone shed some light on what units STLength returns? Feet? Meters? Inches? Help! 回答1: The units are entirely dependent on the Spatial Reference ID (SRID) of the geography

Using real world units instead of types

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问题 I have a project with many calculations involving a lot of real world units : Distance; Temperature; Flow rate; ... This project involves complicated and numerous calculation formulas. That's why I supposed the use of custom types like Temperature , Distance ... can be good for code readability. For example: Temperature x = -55.3; Meter y = 3; or var x = new Temperature(-55.3); I tried to make a Temperature class that uses a double internal value. public class Temperature { double _Value =

Convert letter-tracking value set in Photoshop to equivalent letter-spacing in CSS

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I am currently building a site from a PSD. Most of the fonts have a letter-tracking of -25 ( <- AV-> : I'm guessing that is the symbol for letter spacing?). How would I get the same effect in CSS? I know the property is letter-spacing: X but it doesn't take percentages and -25px or pts would be a huge figure! You can use the em dimension instead of px , thus sizing the spacing relative to the font size (so photoshop's 25% is somewhere around .25em ). In Photoshop letter-spacing is called letter-tracking and is specifically the space between each letter of text. The problem is that Photoshop