Enter a list of numbers, separated by commas or newlines, to generate a stem and leaf display.
Stem and Leaf Display:
Understanding Stem and Leaf Displays
A stem and leaf display is a simple quantitative method of displaying data, commonly used in exploratory data analysis. It separates each data point into a "stem" and a "leaf". The stems are listed vertically in increasing order, and the leaves are listed horizontally to the right of their corresponding stems. This method offers a quick visual summary of the distribution of a dataset, revealing its shape, center, and spread.
How it Works:
Each number in a dataset is split into two parts:
Stem: The leading digit(s) of the number.
Leaf: The trailing digit of the number.
For example, in the number 45:
If the stem unit is 10, the stem is 4 (representing 40) and the leaf is 5.
If the stem unit is 1, the stem is 45 and the leaf is considered to be 0 (or this might indicate the number is fully represented by the stem). The interpretation of "stem unit" is crucial.
The "stem unit" determines how the split occurs. If the stem unit is 10, then a number like 23 would have a stem of 2 and a leaf of 3. A number like 125 might have a stem of 12 and a leaf of 5 (if the stem unit is 10). A number like 7 would have a stem of 0 and a leaf of 7 if the stem unit is 10 (though typically, stem and leaf displays are used for numbers with at least two digits or when comparing numbers of similar magnitude).
Steps to Create a Stem and Leaf Display:
Determine the Stem Unit: Decide how to split the numbers. The most common approach is to let the stem represent all digits except the last one, making the leaf the last digit. The stem unit indicates the place value of the last digit. For example, if the stem unit is 10, then 23 has a stem of 2 and a leaf of 3. If the stem unit is 1, then 23 has a stem of 23 and a leaf of 0 (or no leaf if it's a single-digit number in that context).
List the Stems: Identify all unique stem values in the dataset and list them in ascending order.
Add the Leaves: For each data point, write its leaf next to its corresponding stem.
Order the Leaves: Arrange the leaves for each stem in ascending order.
Add a Key: Include a key that explains how to interpret the stems and leaves (e.g., "Key: 2 | 3 = 23").
function generateStemLeaf() {
var dataInput = document.getElementById("dataInput").value;
var stemUnit = parseInt(document.getElementById("stemUnit").value);
var errorMessageDiv = document.getElementById("errorMessage");
var stemLeafDisplayDiv = document.getElementById("stemLeafDisplay");
errorMessageDiv.innerText = ""; // Clear previous errors
stemLeafDisplayDiv.innerHTML = ""; // Clear previous results
if (isNaN(stemUnit) || stemUnit <= 0) {
errorMessageDiv.innerText = "Invalid Stem Unit. Please enter a positive number.";
return;
}
var numbers = [];
// Split by comma or newline, then filter out empty strings and parse
var values = dataInput.split(/[\n,]+/).filter(function(val) {
return val.trim() !== "";
});
for (var i = 0; i < values.length; i++) {
var num = parseFloat(values[i].trim());
if (!isNaN(num)) {
numbers.push(num);
} else {
errorMessageDiv.innerText += "Warning: Found non-numeric value '" + values[i] + "'. It will be ignored. ";
}
}
if (numbers.length === 0) {
errorMessageDiv.innerText = "No valid numbers entered.";
return;
}
// Sort the numbers to make processing easier and ensure ordered leaves
numbers.sort(function(a, b) { return a – b; });
var stems = {};
var minStem = Infinity;
var maxStem = -Infinity;
for (var i = 0; i stem=2, leaf=3. num=235 -> stem=23, leaf=5.
// If num=23.5 and stemUnit=10, stem=2, leaf=3 (rounding the .5 up).
// If num=23.1 and stemUnit=10, stem=2, leaf=3 (rounding the .1 up).
// A more robust approach for decimals might require a different leaf calculation.
// For typical integer stem-leaf, this is fine. Let's refine the leaf for clarity.
// Recalculate leaf based on the stem and original number to be more precise.
// Example: num=23, stemUnit=10. stem=floor(23/10)=2. leaf = 23 – 2*10 = 3.
// Example: num=125, stemUnit=10. stem=floor(125/10)=12. leaf = 125 – 12*10 = 5.
// Example: num=7, stemUnit=10. stem=floor(7/10)=0. leaf = 7 – 0*10 = 7.
stem = Math.floor(num / stemUnit);
leaf = num – stem * stemUnit;
if (leaf = stemUnit) { // Ensure leaf is within expected range for the stem unit
// This might happen with negative numbers or edge cases.
// For simplicity, we'll ignore such data points or log a warning.
// A more advanced calculator could handle negative stems or different leaf definitions.
errorMessageDiv.innerText += "Warning: Leaf calculation issue for " + num + " with stem unit " + stemUnit + ". It will be ignored. ";
continue;
}
if (!stems[stem]) {
stems[stem] = [];
}
stems[stem].push(leaf);
if (stem maxStem) maxStem = stem;
}
var displayHtml = "Stem | Leaves—–|——–";
for (var s = minStem; s <= maxStem; s++) {
displayHtml += s + " | ";
if (stems[s]) {
// Leaves are already sorted because the input numbers were sorted
// However, if the input numbers were not sorted, we would sort here: stems[s].sort(function(a,b){return a-b;});
for (var i = 0; i < stems[s].length; i++) {
displayHtml += stems[s][i] + " ";
}
}
displayHtml += "";
}
// Add key
if (minStem !== Infinity) {
var exampleLeaf = stems[minStem] ? stems[minStem][0] : 0;
displayHtml += "Key: " + minStem + " | " + exampleLeaf + " = " + (minStem * stemUnit + exampleLeaf);
}
stemLeafDisplayDiv.innerHTML = displayHtml;
}