Knowledge Base

Intuitive maths-oriented expressions for data manipulation.

Introduction

The Nodes: Data Expression feature in Ligantic provides a powerful and flexible way to manipulate data using intuitive, math-oriented expressions. This feature allows you to perform a wide range of data transformations and calculations directly within your Ligantic workflows, without the need for complex programming or scripting.

Expression Syntax

The expression syntax used in Nodes: Data Expression is similar to normal JavaScript expressions, but is more math-oriented.

Operators

In addition to the standard arithmetic operators, Nodes: Data Expression also includes a number of unary operators that can be used to perform various mathematical and logical operations. These include:

• -x: Negation
• +x: Unary plus (converts the operand to a number, but has no other effect)
• x!: Factorial
• abs x: Absolute value (magnitude) of x
• acos x: Arc cosine of x (in radians)
• acosh x: Hyperbolic arc cosine of x (in radians)
• asin x: Arc sine of x (in radians)
• asinh x: Hyperbolic arc sine of x (in radians)
• atan x: Arc tangent of x (in radians)
• atanh x: Hyperbolic arc tangent of x (in radians)
• cbrt x: Cube root of x
• ceil x: Ceiling of x — the smallest integer that's >= x
• cos x: Cosine of x (x is in radians)
• cosh x: Hyperbolic cosine of x (x is in radians)
• exp x: e^x (exponential/antilogarithm function with base e)
• expm1 x: e^x - 1
• floor x: Floor of x — the largest integer that's <= x
• length x: String or array length of x
• ln x: Natural logarithm of x
• log x: Natural logarithm of x (synonym for ln, not base-10)
• log10 x: Base-10 logarithm of x
• log2 x: Base-2 logarithm of x
• log1p x: Natural logarithm of (1 + x)
• not x: Logical NOT operator
• round x: X, rounded to the nearest integer, using "grade-school rounding"
• sign x: Sign of x (-1, 0, or 1 for negative, zero, or positive respectively)
• sin x: Sine of x (x is in radians)
• sinh x: Hyperbolic sine of x (x is in radians)
• sqrt x: Square root of x. Result is NaN (Not a Number) if x is negative.
• tan x: Tangent of x (x is in radians)
• tanh x: Hyperbolic tangent of x (x is in radians)
• trunc x: Integral part of a X, looks like floor(x) unless for negative number

Functions

In addition to the built-in operators, Nodes: Data Expression also includes a number of pre-defined functions that can be used to perform various data manipulation and analysis tasks. These include:

• random(n): Get a random number in the range [0, n). If n is zero, or not provided, it defaults to 1.
• min(a,b,...): Get the smallest (minimum) number in the list.
• max(a,b,...): Get the largest (maximum) number in the list.
• hypot(a,b): Hypotenuse, i.e. the square root of the sum of squares of its arguments.
• pyt(a, b): Alias for hypot.
• pow(x, y): Equivalent to x^y.
• atan2(y, x): Arc tangent of x/y. i.e. the angle between (0, 0) and (x, y) in radians.
• roundTo(x, n): Rounds x to n places after the decimal point.
• map(f, a): Array map: Pass each element of a the function f, and return an array of the results.
• fold(f, y, a): Array fold: Fold/reduce array a into a single value, y by setting y = f(y, x, index) for each element x of the array.
• filter(f, a): Array filter: Return an array containing only the values from a where f(x, index) is true.
• indexOf(x, a): Return the first index of string or array a matching the value x, or -1 if not found.
• join(sep, a): Concatenate the elements of a, separated by sep.
• if(c, a, b): Function form of c ? a : b. Note: This always evaluates both a and b, regardless of whether c is true or not. Use c ? a : b instead if there are side effects, or if evaluating the branches could be expensive.
• addDuration(dateTime, durationValue, durationUnit): Add a duration to a given date and time.
  • dateTime: The starting datetime value.
  • durationValue: The numeric value of the duration to add.
  • durationUnit: The unit of the duration - supported values: hours, minutes, seconds.
• slice(stringOrArray, start, end): Extract a portion of a string or array.
  • stringOrArrayLink: The input string or array to slice.
  • start: The starting index of the slice (inclusive).
  • end: The optional ending index of the slice (exclusive).
• startsWith(string, testString, start)
  • Tests whether a string begins with the characters of another string.
  • Parameters:
    • string: The main string to check
    • testString: The sequence of characters to search for at the beginning of the main string
    • start (optional): The position in the main string at which to begin searching. If omitted, the search starts from index 0
  • Returns:
    • true if the main string begins with testString at the specified position
    • false otherwise
  • Examples:
    • startsWith("Hello World", "Hello")returns true
    • startsWith("Hello World", "World", 6)returns true
    • startsWith("Hello World", "World")returns false

Constants

Nodes: Data Expression also includes a number of pre-defined constants that can be used in expressions, including:

• E: The value of e (mathematical constant), equal to exp 1
• PI: The value of π (mathematical constant)
• true: Logical true value
• false: Logical false value

Use Cases

The Nodes: Data Expression feature in Ligantic can be used for a wide variety of data manipulation and analysis tasks, including:

• Performing mathematical calculations: You can use the various arithmetic and mathematical operators and functions to perform complex calculations on your data.
• Transforming data: You can use the expression syntax to transform data in various ways, such as filtering, mapping, and reducing arrays.
• Conditional logic: You can use the ternary operator and logical operators to implement conditional logic in your data processing workflows.

Overall, the Nodes: Data Expression feature provides a powerful and flexible way to work with data within the Ligantic platform, allowing you to perform a wide range of data manipulation and analysis tasks without the need for complex programming or scripting.