[GitHub] [spark] dtenedor commented on a diff in pull request #36950: [SPARK-38796][SQL] Update documentation for number format strings with the {try_}to_number functions

[GitBox <gi...@apache.org>]

dtenedor commented on code in PR #36950:
URL: https://github.com/apache/spark/pull/36950#discussion_r903134910


##########
docs/sql-ref-number-pattern.md:
##########
@@ -19,4 +19,101 @@ license: |
   limitations under the License.
 ---
 
-TODO: Add the content of Number Patterns for Formatting and Parsing
+### Description
+
+Functions such as `to_number` and `try_to_number` support converting between values of string and
+Decimal type. Such functions accept format strings indicating how to map between these types.
+
+### Syntax

Review Comment:
   Sure, this sounds good. Added this to the docs.



##########
docs/sql-ref-number-pattern.md:
##########
@@ -19,4 +19,101 @@ license: |
   limitations under the License.
 ---
 
-TODO: Add the content of Number Patterns for Formatting and Parsing
+### Description
+
+Functions such as `to_number` and `try_to_number` support converting between values of string and
+Decimal type. Such functions accept format strings indicating how to map between these types.
+
+### Syntax
+
+Number format strings support the following syntax:
+```
+  { ' [ S ] [ L | $ ] 
+      [ 0 | 9 | G | , ] [...] 
+      [ . | D ] 
+      [ 0 | 9 ] [...] 
+      [ L | $ ] [ PR | MI | S ] ' }
+```
+
+### Elements
+
+Each number format string can contain the following elements (case insensitive):
+
+- **`0`** or **`9`**
+
+  Specifies an expected digit between `0` and `9`.
+
+  A `0` to the left of the decimal point indicates that at least this many digits must be present.
+
+  A leading `9` indicates that these digits are optional.
+
+  The input value must not be larger than the number of digits to the left of the decimal point 
+  allowed by the format string.
+
+  Digits to the right of the decimal point in the format string indicate the most digits that the
+  input value may have to the right of the decimal point.
+
+- **`.`** or **`D`**
+
+  Specifies the position of the decimal point.
+
+  The input value does not need to include a decimal point.
+
+- **`,`** or **`G`**
+
+  Specifies the position of the `,` grouping (thousands) separator.
+
+  There must be a `0` or `9` to the left and right of each grouping separator. 
+
+- **`$`**
+
+  Specifies the location of the `$` currency sign. This character may only be specified once.
+
+- **`S`** 
+
+  Specifies the position of an optional '+' or '-' sign. This character may only be specified once.
+
+- **`MI`**
+
+  Specifies an optional `-` sign at the end, but no `+`.
+
+- **`PR`**
+
+  Maps negative input values to wrapping angle brackets (`<1>`) in the corresponding string.
+
+  Positive input values do not receive wrapping angle brackets.
+
+### Examples
+
+The following examples use the `try_to_number` SQL function which accepts an input string as the

Review Comment:
   Added this to the examples section at the end.



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