7.1 KiB
7.1 KiB
Expression
The Expression node allows you to create dynamic expressions using mathematical operations, string manipulations, statistics/probability functions, and conditional logic.
Examples
Basic Operations
- Add two numbers:
a + b - Less than or equal comparison:
a <= b - Return true if a or b is true:
a or b - Return the larger of a and b:
a if a > b else b
Mathematical Functions
- Find minimum value:
min(a, b) - Find maximum value:
max(a, b) - Round to nearest integer:
round(a) - Convert to integer:
int(a) - Convert to float:
float(a)
String Functions
- Convert to lowercase:
lower("{a}") - Convert to uppercase:
upper("{a}") - Replace spaces with ", ":
replace("{a}", " ", ", ") - Check if b is in a:
contains("{a}", "{b}") - Check if a starts with b:
startswith("{a}", "{b}")
Statistical and Probability Functions
- Calculate 5! (5×4×3×2×1 = 120):
factorial(5) - Return true with 30% probability:
rand() < 0.3 - Calculate the mean of values a, b, c, and d:
mean([a, b, c, d]) - Generate a random float between 1 and 1.3 divisible by 0.05 (with clean decimal places):
round(floor(uniform(1, 1.35) / 0.05) * 0.05, 2)
Input
| Name | Type | Description |
|---|---|---|
a |
ANY | The first input variable. |
b |
ANY | The second input variable. |
c |
ANY | The third input variable. |
d |
ANY | The fourth input variable. |
expression |
STRING | The expression to evaluate. |
Output
| Name | Type | Description |
|---|---|---|
INT |
INT | The integer value derived from the expression. |
FLOAT |
FLOAT | The floating-point value derived from the expression. |
STRING |
STRING | The string representation of the result. |
BOOLEAN |
BOOLEAN | The boolean representation of the result. |
Syntax
Expressions follow standard Python syntax with some important notes about variable access:
- For mathematical and logical operations, you can access variables directly in the expression:
a + b,a > b, etc. - To access variables in strings, use curly braces:
"Hello {a}","The sum of {a} and {b} is {a + b}", etc. - Constants
pi,e,i,phican be accessed in the expression like any other variables:a + pi,"π = {pi}", etc.
Error Handling
If the input expression contains an error, the node will output (0, 0.0, error, False). To debug expressions, connect the STRING output to the Preview Text node to see the error.
Available Constants, Operations and Functions
Constants
pi- Mathematical constant π (3.14159...).e- Mathematical constant e (2.71828...).i- Imaginary unit (√-1).phi- Golden ratio (1.61803...).
Arithmetic Operators
a + b- Addition.a - b- Subtraction.a * b- Multiplication.a / b- Division.a // b- Floor Division.a % b- Modulus.a ** b- Power.-a- Negation.
Comparison Operators
a == b- Equal.a != b- Not Equal.a < b- Less Than.a <= b- Less Than or Equal.a > b- Greater Than.a >= b- Greater Than or Equal.
Logical Operators
a and b- And.a or b- Or.not a- Not.a if b else c- Conditional.
Mathematical Functions
min(a, b, ...)- Minimum value.max(a, b, ...)- Maximum value.round(a)- Round to nearest integer.sum([a, b, ...])- Sum of values.abs(a)- Absolute value.sin(a)- Sine (radians).cos(a)- Cosine (radians).tan(a)- Tangent (radians).sqrt(a)- Square root.floor(a)- Floor (round down).ceil(a)- Ceiling (round up).log(a)- Natural logarithm.log10(a)- Base-10 logarithm.exp(a)- Exponential (e^a).asin(a)- Arc sine.acos(a)- Arc cosine.atan(a)- Arc tangent.sinh(a)- Hyperbolic sine.cosh(a)- Hyperbolic cosine.tanh(a)- Hyperbolic tangent.deg(a)- Convert radians to degrees.rad(a)- Convert degrees to radians.real(a)- Get real part of a complex number.imaginary(a)- Get imaginary part of a complex number.
String Functions
lower(str)- Convert to lowercase.upper(str)- Convert to uppercase.replace(str, old, new)- Replace substring.split(str, sep)- Split string into list.join(separator, list)- Join list into string.strip(str)- Remove whitespace from ends.lstrip(str, chars)- Remove whitespace from left.rstrip(str, chars)- Remove whitespace from right.find(str, sub)- Find substring position.contains(str, sub)- Check if substring exists.startswith(str, prefix)- Check if starts with prefix.endswith(str, suffix)- Check if ends with suffix.capitalize(str)- Capitalize first letter.title(str)- Capitalize each word.reverse(str)- Reverse string.count(str, sub)- Count occurrences of substring.zfill(str, width)- Pad with zeros.isalpha(str)- Check if all alphabetic.isdigit(str)- Check if all digits.isalnum(str)- Check if all alphanumeric.isspace(str)- Check if all whitespace.islower(str)- Check if all lowercase.isupper(str)- Check if all uppercase.
Regex Functions
re_sub(pattern, repl, string, count=0)- Substitute occurrences of pattern with repl.re_search(pattern, string)- Search for pattern in string.re_match(pattern, string)- Match pattern at the start of string.re_findall(pattern, string)- Find all occurrences of pattern.re_split(pattern, string, maxsplit=0)- Split string by pattern.re_escape(string)- Escape special characters in string.
Statistics and Probability Functions
mean(list)- Calculate arithmetic mean of a list of values.median(list)- Calculate the median value.mode(list)- Find the most common value.stdev(list)- Calculate sample standard deviation.variance(list)- Calculate sample variance.pstdev(list)- Calculate population standard deviation.pvariance(list)- Calculate population variance.normal_pdf(x, mu, sigma)- Normal probability density function.normal_cdf(x, mu, sigma)- Normal cumulative distribution function.factorial(n)- Calculate factorial of n.comb(n, k)- Number of ways to choose k items from n items without repetition and order.perm(n, k)- Number of ways to choose k items from n items without repetition with order.random()- Random float between 0 and 1.randint(a, b)- Random integer between a and b (inclusive).uniform(a, b)- Random float between a and b.choice(list)- Random item from list.gauss(mu, sigma)- Random value from normal distribution.
Other Functions
int(a)- Convert to integer.float(a)- Convert to float.bool(a)- Convert to boolean.list(a, sep=",")- Convert string into list with separator (default is comma).len(a)- Length of a string or list.