[add] Implement variable padding in number rounding

README.md

@@ -210,8 +210,9 @@ Rounding can be configured with the `set-round()` function.
     then the number is rounded to the same number of decimal places as the 
     uncertainty. 
 - `precision: int | none = 2` : The precision to round to. Also see parameter `mode`. When set to `none`, no rounding is applied. 
-- `pad: bool = true` : Whether to pad the number with zeros if the 
-   number has fewer digits than the rounding precision. 
+- `pad: bool | int = true` : Whether to pad the number with zeros if the 
+   number has fewer digits than the rounding precision. When an integer is passed, it defines the minimum number of decimal digits to display 
+   for `mode: "places"` and the minimum number of significant figures for `mode: "figures"`. The parameter `pad` has no effect for `mode: "uncertainty"`.
 - `direction: str = "nearest"` : Sets the rounding direction. 
   - `"nearest"`: Rounding takes place in the usual fashion, rounding to the nearer 
     number, e.g., 2.3 → 2 and 2.6 → 3. 

src/rounding.typ

@@ -94,6 +94,7 @@
   dir: "nearest",
   ties: "away-from-zero",
   pad: true,
+  precision: 2
 ) = {
   total-digits = calc.max(0, total-digits)
   let number = int + frac
@@ -112,6 +113,9 @@
 
     int = number.slice(0, new-int-digits)
     frac = number.slice(new-int-digits)
+  } else if type(pad) == std.int {
+    let max-pad = total-digits - number.len()
+    frac += "0" * calc.clamp(pad - precision + max-pad, 0, max-pad)
   } else if pad {
     frac += "0" * (total-digits - number.len())
   }
@@ -144,8 +148,10 @@
   direction: "nearest",
   ties: "away-from-zero",
   /// Determines whether the number should be padded with zeros if the number has less
-  /// digits than the rounding precision.
-  /// -> bool
+  /// digits than the rounding precision. If an integer is given, determines the minimum
+  /// number of decimal digits (`mode: "places"`) or significant figures (`mode: "figures"`)
+  /// to display. The parameter `pad` has no effect in `mode: "uncertainty"`.
+  /// -> bool | int
   pad: true,
   /// Uncertainty
   pm: none,
@@ -192,7 +198,7 @@
     let is-symmetric = type(pm.first()) != array
     if is-symmetric {
       round-digit-pm = count-leading-zeros(pm.join()) + precision
-      pm = round-or-pad(..pm, round-digit-pm, dir: direction, pad: true)
+      pm = round-or-pad(..pm, round-digit-pm, dir: direction, pad: true, precision: precision)
       round-digit = round-digit-pm + int.len() - pm.first().len()
     } else {
       let place = calc.max(
@@ -206,6 +212,7 @@
         place + u.first().len(),
         dir: direction,
         pad: true,
+        precision: precision
       ))
     }
   }
@@ -219,6 +226,7 @@
       pad: pad,
       sign: sign,
       ties: ties,
+      precision: precision
     ),
     pm,
   )

tests/rounding/test.typ

@@ -136,8 +136,13 @@
 #assert.eq(round-places("1", "1", precision: 3), ("1", "100", none))
 #assert.eq(round-places("1", "1", precision: 5), ("1", "10000", none))
 #assert.eq(round-places("1", "1", precision: 5), ("1", "10000", none))
-#assert.eq(round-places("1", "1", precision: 5, pad: false), ("1", "1", none))
 
+#assert.eq(round-places("1", "1", precision: 5, pad: false), ("1", "1", none))
+#assert.eq(round-places("1", "1", precision: 5, pad: true), ("1", "10000", none))
+#assert.eq(round-places("1", "1", precision: 5, pad: -1), ("1", "1", none))
+#assert.eq(round-places("1", "1", precision: 5, pad: 0), ("1", "1", none))
+#assert.eq(round-places("1", "1", precision: 5, pad: 3), ("1", "100", none))
+#assert.eq(round-places("1", "1", precision: 5, pad: 6), ("1", "10000", none))
 
 #assert.eq(round-figures("1", "234", precision: 4), ("1", "234", none))
 #assert.eq(round-figures("1", "234", precision: 3), ("1", "23", none))
@@ -147,11 +152,23 @@
 #assert.eq(round-figures("1", "234", precision: -1), ("0", "", none))
 
 #assert.eq(round-figures("1", "2", precision: 4), ("1", "200", none))
+
 #assert.eq(round-figures("1", "2", precision: 4, pad: false), ("1", "2", none))
+#assert.eq(round-figures("1", "2", precision: 4, pad: true), ("1", "200", none))
+#assert.eq(round-figures("1", "2", precision: 4, pad: -1), ("1", "2", none))
+#assert.eq(round-figures("1", "2", precision: 4, pad: 0), ("1", "2", none))
+#assert.eq(round-figures("1", "2", precision: 4, pad: 3), ("1", "20", none))
+#assert.eq(round-figures("1", "2", precision: 4, pad: 6), ("1", "200", none))
 
 #assert.eq(round-figures("0", "00126", precision: 2), ("0", "0013", none))
 #assert.eq(round-figures("0", "000126", precision: 3), ("0", "000126", none))
 
+#assert.eq(round-figures("0", "0016", precision: 4, pad: false), ("0", "0016", none))
+#assert.eq(round-figures("0", "0016", precision: 4, pad: true), ("0", "001600", none))
+#assert.eq(round-figures("0", "0016", precision: 4, pad: -1), ("0", "0016", none))
+#assert.eq(round-figures("0", "0016", precision: 4, pad: 0), ("0", "0016", none))
+#assert.eq(round-figures("0", "0016", precision: 4, pad: 3), ("0", "00160", none))
+#assert.eq(round-figures("0", "0016", precision: 4, pad: 6), ("0", "001600", none))
 
 
 #assert.eq(round-places("99", "92", precision: 2), ("99", "92", none))