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decode

Input Stack:
format: String
expr: TimeSeriesExpr
 ⇨ Output Stack:
StyleExpr
 

Decode encoded characters in legend text for improved presentation. This operator reverses the encoding that clients often apply to tag values when special characters need to be transmitted safely in URIs. It's primarily used for making legends more readable by converting encoded symbols back to their original form.

Warning

Use Sparingly: Avoid encoding structural information into tag values. This feature should be used carefully to prevent combinatorial explosion of tag combinations.

Parameters

  • expr: The time series expression whose legend text will be decoded
  • format: The decoding format to apply (none or hex)

Decoding Formats

none (Default)

  • Behavior: No modification to legend strings
  • Use case: When no decoding is needed or to explicitly disable decoding

hex (Hex Decoding)

  • Behavior: Decodes hex-encoded characters using _ as the escape prefix
  • Format: Similar to URL encoding but uses _ instead of %
  • Lenient parsing: Invalid hex digits are copied without modification
  • Example: _21 → !, _25 → %, _26 → &, _3F → ?

Examples

Converting hex-encoded legend text to readable ASCII:

Hex to ASCII
1,one_21_25_26_3F,:legend,
hex,:decode

This converts the legend one_21_25_26_3F to one!%&? for better readability.

  • :legend - Set custom legend text (often used before decoding)
  • :format - Dynamic string formatting for legends

See Also

Since: 1.5