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Fix engineering formatting

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This commit is contained in:
Austen Adler 2021-05-13 22:19:39 -04:00
parent bab2904495
commit 4e1e256461
1 changed files with 32 additions and 14 deletions
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46
src/main.rs
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@ -404,13 +404,18 @@ fn fmt_scientific(f: f64, precision: usize) -> String {
}; };
let sign = if !ret.starts_with('-') { " " } else { "" }; let sign = if !ret.starts_with('-') { " " } else { "" };
format!("{}{}E{}{:0>pad$}", sign, ret, exp_sign, exp, pad = 2) format!("{}{} E{}{:0>pad$}", sign, ret, exp_sign, exp, pad = 2)
} }
fn fmt_engineering(f: f64, precision: usize) -> String { fn fmt_engineering(f: f64, precision: usize) -> String {
// Format the string so the first digit is always in the first column, and remove '.'. Requested precision + 2 to account for using 1, 2, or 3 digits for the whole portion of the string // Format the string so the first digit is always in the first column, and remove '.'. Requested precision + 2 to account for using 1, 2, or 3 digits for the whole portion of the string
// 1,000 => 1000E3 // 1,000 => 1000E3
let all = format!(" {:.precision$E}", f, precision = precision + 2).replacen(".", "", 1); let all = format!(" {:.precision$E}", f, precision = precision)
// Remove . since it can be moved
.replacen(".", "", 1)
// Add 00E before E here so the length is enough for slicing below
.replacen("E", "00E", 1);
println!("{}", all);
// Extract mantissa and the string representation of the exponent. Unwrap should be safe as formatter will insert E // Extract mantissa and the string representation of the exponent. Unwrap should be safe as formatter will insert E
// 1000E3 => (1000, E3) // 1000E3 => (1000, E3)
let (num_str, exp_str) = all.split_at(all.find('E').unwrap()); let (num_str, exp_str) = all.split_at(all.find('E').unwrap());
@ -471,20 +476,27 @@ mod tests {
fn test_fmt_scientific() { fn test_fmt_scientific() {
for (f, p, s) in vec![ for (f, p, s) in vec![
// Basic // Basic
(1.0, 0, " 1E+00"), (1.0, 0, " 1 E+00"),
(-1.0, 0, "-1E+00"), (-1.0, 0, "-1 E+00"),
(100.0, 0, " 1E+02"), (100.0, 0, " 1 E+02"),
(0.1, 0, " 1E-01"), (0.1, 0, " 1 E-01"),
(0.01, 0, " 1E-02"), (0.01, 0, " 1 E-02"),
(-0.1, 0, "-1E-01"), (-0.1, 0, "-1 E-01"),
// i // i
(1.0, 0, " 1E+00"), (1.0, 0, " 1 E+00"),
// Precision // Precision
(-0.123456789, 3, "-1.235E-01"), (-0.123456789, 3, "-1.235 E-01"),
(-0.123456789, 2, "-1.23E-01"), (-0.123456789, 2, "-1.23 E-01"),
(-0.123456789, 2, "-1.23E-01"), (-0.123456789, 2, "-1.23 E-01"),
(-1e99, 2, "-1.00E+99"), (-1e99, 2, "-1.00 E+99"),
(-1e100, 2, "-1.00E+100"), (-1e100, 2, "-1.00 E+100"),
// Rounding
(0.5, 2, " 5.00 E-01"),
(0.5, 1, " 5.0 E-01"),
(0.5, 0, " 5 E-01"),
(1.5, 2, " 1.50 E+00"),
(1.5, 1, " 1.5 E+00"),
(1.5, 0, " 2 E+00"),
] { ] {
assert_eq!(fmt_scientific(f, p), s); assert_eq!(fmt_scientific(f, p), s);
} }
@ -526,6 +538,12 @@ mod tests {
(0.001, 2, " 1.00 E-03"), (0.001, 2, " 1.00 E-03"),
(0.0001, 2, " 100.00 E-06"), (0.0001, 2, " 100.00 E-06"),
// Rounding // Rounding
(0.5, 2, " 500.00 E-03"),
(0.5, 1, " 500.0 E-03"),
(0.5, 0, " 500. E-03"),
(1.5, 2, " 1.50 E+00"),
(1.5, 1, " 1.5 E+00"),
(1.5, 0, " 2. E+00"),
] { ] {
assert_eq!(fmt_engineering(f, c), s); assert_eq!(fmt_engineering(f, c), s);
} }