signifix
Number Formatter of Fixed Significance with Metric or Binary Prefix
Formats a given number in one of the three Signifix notations
as defined below by determining
- the appropriate metric or binary prefix and
- the decimal mark position in such a way as to sustain a fixed number of
four significant figures.
Contents
Signifix Notations
Three notations are defined,
With Metric Prefix
The two Signifix notations with metric prefix comprise
- a signed significand of four significant figures normalized from
±1.000
to ±999.9
to cover the three powers of ten of a particular
metric prefix with the three different decimal mark positions between
these four figures, and
- a metric prefix symbol or its placeholder in case of no prefix
- either being appended along with a whitespace as in
±1.234␣k
,
that is the default notation,
- or replacing the decimal mark of the significand as in
±1k234
,
that is the alternate notation.
In default notation the placeholder is another whitespace as in ±1.234␣␣
to align consistently, while in alternate notation it is a number sign as in
±1#234
to conspicuously separate the integer from the fractional part of
the significand. The locale-sensitive decimal mark defaults to a decimal
point. The plus sign of positive numbers is optional.
With Binary Prefix
The one Signifix notation with binary prefix comprises
- a signed significand of four significant figures normalized from
±1.000
over ±999.9
to ±1 023
to cover the four powers of ten of a
particular binary prefix with the three different decimal mark positions
between these four figures and a thousands separator, and
- a binary prefix symbol or its placeholder in case of no prefix being
appended along with a whitespace as in
±1.234␣Ki
.
To align consistently, the placeholder is another two whitespaces as in
±1.234␣␣␣
. The locale-sensitive decimal mark defaults to a decimal point
while the locale-sensitive thousands separator defaults to a whitespace as
in ±1␣023␣Ki
. The plus sign of positive numbers is optional.
Usage
This crate works since Rust 1.34 on stable channel. It is
on crates.io and can be used by adding
signifix
to the dependencies in your project's Cargo.toml
:
[dependencies]
signifix = "0.10"
Examples
The Notations
The Signifix notations result in a fixed number of characters preventing
jumps to the left or right while making maximum use of their occupied space:
use std::convert::TryFrom;
use signifix::{metric, binary, Result};
let metric = |number| -> Result<(String, String)> {
let number = metric::Signifix::try_from(number)?;
Ok((format!("{}", number), format!("{:#}", number)))
};
let binary = |number| -> Result<String> {
let number = binary::Signifix::try_from(number)?;
Ok(format!("{}", number))
};
assert_eq!(metric(1E-04), Ok(("100.0 µ".into(), "100µ0".into()))); assert_eq!(metric(1E-03), Ok(("1.000 m".into(), "1m000".into()))); assert_eq!(metric(1E-02), Ok(("10.00 m".into(), "10m00".into()))); assert_eq!(metric(1E-01), Ok(("100.0 m".into(), "100m0".into()))); assert_eq!(metric(1E+00), Ok(("1.000 ".into(), "1#000".into()))); assert_eq!(metric(1E+01), Ok(("10.00 ".into(), "10#00".into()))); assert_eq!(metric(1E+02), Ok(("100.0 ".into(), "100#0".into()))); assert_eq!(metric(1E+03), Ok(("1.000 k".into(), "1k000".into()))); assert_eq!(metric(1E+04), Ok(("10.00 k".into(), "10k00".into()))); assert_eq!(metric(1E+05), Ok(("100.0 k".into(), "100k0".into()))); assert_eq!(metric(1E+06), Ok(("1.000 M".into(), "1M000".into())));
assert_eq!(binary(1_024f64.powi(0) * 1E+00), Ok("1.000 ".into())); assert_eq!(binary(1_024f64.powi(0) * 1E+01), Ok("10.00 ".into())); assert_eq!(binary(1_024f64.powi(0) * 1E+02), Ok("100.0 ".into())); assert_eq!(binary(1_024f64.powi(0) * 1E+03), Ok("1 000 ".into())); assert_eq!(binary(1_024f64.powi(1) * 1E+00), Ok("1.000 Ki".into())); assert_eq!(binary(1_024f64.powi(1) * 1E+01), Ok("10.00 Ki".into())); assert_eq!(binary(1_024f64.powi(1) * 1E+02), Ok("100.0 Ki".into())); assert_eq!(binary(1_024f64.powi(1) * 1E+03), Ok("1 000 Ki".into())); assert_eq!(binary(1_024f64.powi(2) * 1E+00), Ok("1.000 Mi".into()));
assert_eq!(metric(999.949_999_999_999_8),
Ok(("999.9 ".into(), "999#9".into())));
assert_eq!(metric(999.949_999_999_999_9),
Ok(("1.000 k".into(), "1k000".into())));
assert_eq!(binary(1_023.499_999_999_999_94),
Ok("1 023 ".into()));
assert_eq!(binary(1_023.499_999_999_999_95),
Ok("1.000 Ki".into()));
Transfer Rate
This is useful to smoothly refresh a transfer rate within a terminal:
use std::convert::TryFrom;
use std::f64;
use std::time::Duration;
use signifix::metric::{Signifix, Error, DEF_MIN_LEN};
let transfer_rate = |bytes: u64, duration: Duration| -> String {
let seconds = duration.as_secs() as f64
+ duration.subsec_nanos() as f64 * 1E-09;
let bytes_per_second = bytes as f64 / seconds;
let unit = "B/s";
let rate = match Signifix::try_from(bytes_per_second) {
Ok(rate) => if rate.factor() < 1E+00 {
" - slow - ".into() } else {
format!("{}{}", rate, unit) },
Err(case) => match case {
Error::OutOfLowerBound(rate) => if rate == 0f64 {
" - idle - " } else {
" - slow - " },
Error::OutOfUpperBound(rate) => if rate == f64::INFINITY {
" - ---- - " } else {
" - fast - " },
Error::Nan => " - ---- - ", }.into(),
};
debug_assert_eq!(rate.chars().count(),
DEF_MIN_LEN + unit.chars().count());
rate
};
assert_eq!(transfer_rate(42_667, Duration::from_secs(300)), "142.2 B/s");
assert_eq!(transfer_rate(42_667, Duration::from_secs(030)), "1.422 kB/s");
assert_eq!(transfer_rate(42_667, Duration::from_secs(003)), "14.22 kB/s");
assert_eq!(transfer_rate(00_001, Duration::from_secs(003)), " - slow - ");
assert_eq!(transfer_rate(00_000, Duration::from_secs(003)), " - idle - ");
assert_eq!(transfer_rate(42_667, Duration::from_secs(000)), " - ---- - ");
Measured Amps
Or to monitor a measured quantity like an electrical current including its
direction with positive numbers being padded to align with negative ones:
use std::convert::TryFrom;
use signifix::metric::{Signifix, Result, DEF_MAX_LEN};
let measured_amps = |amps| -> Result<String> {
if let Some(amps) = amps {
Signifix::try_from(amps)
.map(|amps| format!("{:>1$}A", amps, DEF_MAX_LEN))
} else {
Ok(" 0 A".into())
}
};
assert_eq!(measured_amps(Some( 1.476E-06)), Ok(" 1.476 µA".into()));
assert_eq!(measured_amps(None), Ok(" 0 A".into()));
assert_eq!(measured_amps(Some(-2.927E-06)), Ok("-2.927 µA".into()));
Filesize Diff
While to visualize a change in file size, a plus sign might be preferred for
positive numbers:
use std::convert::TryFrom;
use signifix::metric::{Signifix, Error, Result};
let filesize_diff = |curr, prev| -> Result<String> {
Signifix::try_from(curr - prev).map(|diff| format!("{:+#}", diff))
.or_else(|case| if case == Error::OutOfLowerBound(0f64)
{ Ok("=const".into()) } else { Err(case) })
};
assert_eq!(filesize_diff(78_346, 57_393), Ok("+20k95".into()));
assert_eq!(filesize_diff(93_837, 93_837), Ok("=const".into()));
assert_eq!(filesize_diff(27_473, 36_839), Ok("-9k366".into()));
Boundary Stat
The binary prefix instead suits well to visualize quantities being multiples
of powers of two, such as memory boundaries due to binary addressing:
use std::convert::TryFrom;
use signifix::binary::{Signifix, Error, Result};
let boundary_stat = |used: u64, size: u64| -> Result<String> {
if used == 0 {
let size = Signifix::try_from(size)?;
return Ok(format!(" 0 B ( 0 %) of {}B", size));
}
let p100 = Signifix::try_from(used as f64 / size as f64 * 100.0)
.map(|p100| format!("{:.*} %", p100.exponent(), p100.significand()))
.or_else(|error| if let Error::OutOfLowerBound(_) = error
{ Ok(" < 1 %".into()) } else { Err(error) })?;
let used = Signifix::try_from(used)?;
let size = Signifix::try_from(size)?;
Ok(format!("{}B ({}) of {}B", used, p100, size))
};
assert_eq!(boundary_stat(0_000u64.pow(1), 1_024u64.pow(3)),
Ok(" 0 B ( 0 %) of 1.000 GiB".into()));
assert_eq!(boundary_stat(1_024u64.pow(2), 1_024u64.pow(3)),
Ok("1.000 MiB ( < 1 %) of 1.000 GiB".into()));
assert_eq!(boundary_stat(3_292u64.pow(2), 1_024u64.pow(3)),
Ok("10.34 MiB (1.009 %) of 1.000 GiB".into()));
assert_eq!(boundary_stat(8_192u64.pow(2), 1_024u64.pow(3)),
Ok("64.00 MiB (6.250 %) of 1.000 GiB".into()));
assert_eq!(boundary_stat(1_000u64.pow(3), 1_024u64.pow(3)),
Ok("953.7 MiB (93.13 %) of 1.000 GiB".into()));
assert_eq!(boundary_stat(1_024u64.pow(3), 1_024u64.pow(3)),
Ok("1.000 GiB (100.0 %) of 1.000 GiB".into()));
Localizations
Until there is a recommended and possibly implicit localization system for
Rust, explicit localization can be achieved by wrapping the Signifix
type
into a locale-sensitive newtype which implements the Display
trait via the
Signifix::fmt()
method:
use std::convert::TryFrom;
use signifix::binary::{Signifix, Result};
struct SignifixSi(Signifix); struct SignifixEn(Signifix); struct SignifixDe(Signifix);
impl std::fmt::Display for SignifixSi {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
std::fmt::Display::fmt(&self.0, f)
}
}
impl std::fmt::Display for SignifixEn {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
self.0.fmt(f, ".", ",")
}
}
impl std::fmt::Display for SignifixDe {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
self.0.fmt(f, ",", ".")
}
}
let localizations = |number| -> Result<(String, String, String)> {
Signifix::try_from(number).map(|number| (
format!("{}", SignifixSi(number)),
format!("{}", SignifixEn(number)),
format!("{}", SignifixDe(number)),
))
};
assert_eq!(localizations(999.9f64 * 1_024f64),
Ok(("999.9 Ki".into(), "999.9 Ki".into(), "999,9 Ki".into())));
assert_eq!(localizations(1_000f64 * 1_024f64),
Ok(("1 000 Ki".into(), "1,000 Ki".into(), "1.000 Ki".into())));
Customization
Customization can be achieved by extracting information from the Signifix
type via its methods:
use std::convert::TryFrom;
use signifix::metric::{Signifix, Result};
struct SignifixTable<'a>(&'a[Signifix]);
impl<'a> std::fmt::Display for SignifixTable<'a> {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
f.pad(" Int Fra 10³\n")?;
f.pad("---- ---- ----\n")?;
for entry in self.0 {
let (integer, fractional) = entry.parts();
f.pad(&format!("{:4} {:<3} {:2}\n",
integer, fractional, entry.prefix() as i32 - 8))?;
}
Ok(())
}
}
let customization = |entries: &[_]| -> Result<String> {
let mut table = Vec::with_capacity(entries.len());
for entry in entries {
table.push(Signifix::try_from(*entry)?);
}
Ok(SignifixTable(&table).to_string())
};
assert_eq!(customization(&[
1.234E-06,
12.34E+00,
-123.4E+24,
]), Ok(concat!(
" Int Fra 10³\n",
"---- ---- ----\n",
" 1 234 -2\n",
" 12 34 0\n",
"-123 4 8\n",
).into()));
License
Copyright (c) 2016-2019 Rouven Spreckels n3vu0r@qu1x.org
Usage of the works is permitted provided that
this instrument is retained with the works, so that
any entity that uses the works is notified of this instrument.
DISCLAIMER: THE WORKS ARE WITHOUT WARRANTY.
Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the works by you shall be licensed as above, without any
additional terms or conditions.