Task 138: .DIF File Format
Task 138: .DIF File Format
The .DIF file format, also known as Data Interchange Format, is a text-based format originally developed for VisiCalc to facilitate the import and export of spreadsheet data. It consists of a header section describing the data structure and an optional data section containing the actual values. The format uses ASCII characters, with header items structured in three-line chunks and data items in two-line chunks.
- Based on the specifications, the following is a comprehensive list of properties intrinsic to the .DIF file format. These are derived from the header section and represent metadata about the file and its data organization. They do not include the actual data values, which are stored separately in the data section.
- Version: An integer specifying the DIF format version (typically 1 for standard compliance).
- Title: A string providing a descriptive title for the data set.
- Number of Vectors: An integer indicating the number of vectors (typically columns in a spreadsheet context).
- Number of Tuples: An integer indicating the number of tuples (typically rows in a spreadsheet context).
- Labels: A collection of strings, optionally specified per vector and line number, providing labels for vectors.
- Comments: A collection of strings, optionally specified per vector and line number, providing descriptive comments for vectors.
- Sizes: A collection of integers, optionally specified per vector, indicating fixed field sizes in bytes.
- Periodicities: A collection of integers, optionally specified per vector, indicating periods in time series data.
- Major Starts: A collection of integers, optionally specified per vector, indicating the starting year for time series data.
- Minor Starts: A collection of integers, optionally specified per vector, indicating the starting period for time series data.
- True Lengths: A collection of integers, optionally specified per vector, indicating the length of significant data within each vector.
- Units: A collection of strings, optionally specified per vector, indicating units of measurement for vector values.
- Display Units: A collection of strings, optionally specified per vector, indicating units for displaying vector values (may differ from storage units).
- The following are two direct download links for sample .DIF files:
- The following is an embeddable HTML snippet with JavaScript suitable for a Ghost blog post (or similar platform). It creates a drag-and-drop area where a user can drop a .DIF file. The script reads the file, parses the header to extract the properties listed above, and displays them on the screen. It assumes the file is text-based and handles basic error checking.
Drag and drop a .DIF file here
- The following is a Python class for handling .DIF files. It includes methods to open and read a file, decode (parse) the header, print the properties to the console, and write a new .DIF file with specified properties (using minimal example data for demonstration).
import os
class DIFHandler:
def __init__(self, filename=None):
self.filename = filename
self.properties = {
'version': None,
'title': None,
'num_vectors': None,
'num_tuples': None,
'labels': {},
'comments': {},
'sizes': {},
'periodicities': {},
'major_starts': {},
'minor_starts': {},
'true_lengths': {},
'units': {},
'display_units': {}
}
if filename:
self.read()
def read(self):
if not self.filename or not os.path.exists(self.filename):
raise FileNotFoundError("File not found.")
with open(self.filename, 'r') as f:
content = f.read()
self.decode(content)
def decode(self, content):
lines = [line.strip() for line in content.splitlines()]
i = 0
while i < len(lines) and lines[i] != 'DATA':
topic = lines[i]
vector, num_value = map(int, lines[i+1].split(','))
str_value = lines[i+2].strip('"')
if topic == 'TABLE':
self.properties['version'] = num_value
self.properties['title'] = str_value
elif topic == 'VECTORS':
self.properties['num_vectors'] = num_value
elif topic == 'TUPLES':
self.properties['num_tuples'] = num_value
elif topic == 'LABEL':
if vector not in self.properties['labels']:
self.properties['labels'][vector] = []
self.properties['labels'][vector].append({'line': num_value, 'label': str_value})
elif topic == 'COMMENT':
if vector not in self.properties['comments']:
self.properties['comments'][vector] = []
self.properties['comments'][vector].append({'line': num_value, 'comment': str_value})
elif topic == 'SIZE':
self.properties['sizes'][vector] = num_value
elif topic == 'PERIODICITY':
self.properties['periodicities'][vector] = num_value
elif topic == 'MAJORSTART':
self.properties['major_starts'][vector] = num_value
elif topic == 'MINORSTART':
self.properties['minor_starts'][vector] = num_value
elif topic == 'TRUELENGTH':
self.properties['true_lengths'][vector] = num_value
elif topic == 'UNITS':
self.properties['units'][vector] = str_value
elif topic == 'DISPLAYUNITS':
self.properties['display_units'][vector] = str_value
i += 3
def print_properties(self):
for key, value in self.properties.items():
print(f"{key}: {value}")
def write(self, output_filename, properties=None, example_data=None):
if properties:
self.properties.update(properties)
with open(output_filename, 'w') as f:
# Write header
if self.properties['version'] is not None and self.properties['title'] is not None:
f.write('TABLE\n')
f.write(f"0,{self.properties['version']}\n")
f.write(f'"{self.properties["title"]}"\n')
if self.properties['num_vectors'] is not None:
f.write('VECTORS\n')
f.write(f"0,{self.properties['num_vectors']}\n")
f.write('""\n')
if self.properties['num_tuples'] is not None:
f.write('TUPLES\n')
f.write(f"0,{self.properties['num_tuples']}\n")
f.write('""\n')
# Write optional properties (example for labels, etc.)
for vector, labels in self.properties['labels'].items():
for label in labels:
f.write('LABEL\n')
f.write(f"{vector},{label['line']}\n")
f.write(f'"{label["label"]}"\n')
# Similarly for other optionals (omitted for brevity; implement as needed)
f.write('DATA\n')
f.write('0,0\n')
f.write('""\n')
# Write example data if provided (minimal: one row with numeric and string)
if example_data:
f.write('-1,0\n')
f.write('BOT\n')
for cell in example_data:
if isinstance(cell, (int, float)):
f.write(f'0,{cell}\n')
f.write('V\n')
elif isinstance(cell, str):
f.write('1,0\n')
f.write(f'"{cell}"\n')
f.write('-1,0\n')
f.write('EOD\n')
- The following is a Java class for handling .DIF files. It includes methods to open and read a file, decode the header, print the properties to the console, and write a new .DIF file with specified properties (using minimal example data for demonstration).
import java.io.*;
import java.util.*;
public class DIFHandler {
private String filename;
private Map<String, Object> properties = new HashMap<>();
public DIFHandler(String filename) {
this.filename = filename;
initializeProperties();
if (filename != null) {
read();
}
}
private void initializeProperties() {
properties.put("version", null);
properties.put("title", null);
properties.put("num_vectors", null);
properties.put("num_tuples", null);
properties.put("labels", new HashMap<Integer, List<Map<String, Object>>>());
properties.put("comments", new HashMap<Integer, List<Map<String, Object>>>());
properties.put("sizes", new HashMap<Integer, Integer>());
properties.put("periodicities", new HashMap<Integer, Integer>());
properties.put("major_starts", new HashMap<Integer, Integer>());
properties.put("minor_starts", new HashMap<Integer, Integer>());
properties.put("true_lengths", new HashMap<Integer, Integer>());
properties.put("units", new HashMap<Integer, String>());
properties.put("display_units", new HashMap<Integer, String>());
}
public void read() {
try (BufferedReader reader = new BufferedReader(new FileReader(filename))) {
StringBuilder content = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
content.append(line).append("\n");
}
decode(content.toString());
} catch (IOException e) {
System.err.println("File not found or error reading file.");
}
}
public void decode(String content) {
String[] lines = content.split("\n");
for (int i = 0; i < lines.length && !lines[i].trim().equals("DATA"); i += 3) {
String topic = lines[i].trim();
String[] parts = lines[i + 1].trim().split(",");
int vector = Integer.parseInt(parts[0]);
int numValue = Integer.parseInt(parts[1]);
String strValue = lines[i + 2].trim().replaceAll("^\"|\"$", "");
if (topic.equals("TABLE")) {
properties.put("version", numValue);
properties.put("title", strValue);
} else if (topic.equals("VECTORS")) {
properties.put("num_vectors", numValue);
} else if (topic.equals("TUPLES")) {
properties.put("num_tuples", numValue);
} else if (topic.equals("LABEL")) {
@SuppressWarnings("unchecked")
Map<Integer, List<Map<String, Object>>> labels = (Map<Integer, List<Map<String, Object>>>) properties.get("labels");
labels.computeIfAbsent(vector, k -> new ArrayList<>()).add(Map.of("line", numValue, "label", strValue));
} else if (topic.equals("COMMENT")) {
@SuppressWarnings("unchecked")
Map<Integer, List<Map<String, Object>>> comments = (Map<Integer, List<Map<String, Object>>>) properties.get("comments");
comments.computeIfAbsent(vector, k -> new ArrayList<>()).add(Map.of("line", numValue, "comment", strValue));
} else if (topic.equals("SIZE")) {
@SuppressWarnings("unchecked")
Map<Integer, Integer> sizes = (Map<Integer, Integer>) properties.get("sizes");
sizes.put(vector, numValue);
} else if (topic.equals("PERIODICITY")) {
@SuppressWarnings("unchecked")
Map<Integer, Integer> periodicities = (Map<Integer, Integer>) properties.get("periodicities");
periodicities.put(vector, numValue);
} else if (topic.equals("MAJORSTART")) {
@SuppressWarnings("unchecked")
Map<Integer, Integer> majorStarts = (Map<Integer, Integer>) properties.get("major_starts");
majorStarts.put(vector, numValue);
} else if (topic.equals("MINORSTART")) {
@SuppressWarnings("unchecked")
Map<Integer, Integer> minorStarts = (Map<Integer, Integer>) properties.get("minor_starts");
minorStarts.put(vector, numValue);
} else if (topic.equals("TRUELENGTH")) {
@SuppressWarnings("unchecked")
Map<Integer, Integer> trueLengths = (Map<Integer, Integer>) properties.get("true_lengths");
trueLengths.put(vector, numValue);
} else if (topic.equals("UNITS")) {
@SuppressWarnings("unchecked")
Map<Integer, String> units = (Map<Integer, String>) properties.get("units");
units.put(vector, strValue);
} else if (topic.equals("DISPLAYUNITS")) {
@SuppressWarnings("unchecked")
Map<Integer, String> displayUnits = (Map<Integer, String>) properties.get("display_units");
displayUnits.put(vector, strValue);
}
}
}
public void printProperties() {
properties.forEach((key, value) -> System.out.println(key + ": " + value));
}
public void write(String outputFilename, Map<String, Object> newProperties, List<Object> exampleData) throws IOException {
if (newProperties != null) {
properties.putAll(newProperties);
}
try (BufferedWriter writer = new BufferedWriter(new FileWriter(outputFilename))) {
// Write header (example)
if (properties.get("version") != null && properties.get("title") != null) {
writer.write("TABLE\n");
writer.write("0," + properties.get("version") + "\n");
writer.write("\"" + properties.get("title") + "\"\n");
}
if (properties.get("num_vectors") != null) {
writer.write("VECTORS\n");
writer.write("0," + properties.get("num_vectors") + "\n");
writer.write("\"\" \n");
}
if (properties.get("num_tuples") != null) {
writer.write("TUPLES\n");
writer.write("0," + properties.get("num_tuples") + "\n");
writer.write("\"\" \n");
}
// Write optional (labels example)
@SuppressWarnings("unchecked")
Map<Integer, List<Map<String, Object>>> labels = (Map<Integer, List<Map<String, Object>>>) properties.get("labels");
for (Map.Entry<Integer, List<Map<String, Object>>> entry : labels.entrySet()) {
for (Map<String, Object> label : entry.getValue()) {
writer.write("LABEL\n");
writer.write(entry.getKey() + "," + label.get("line") + "\n");
writer.write("\"" + label.get("label") + "\"\n");
}
}
// Similarly for others (omitted for brevity)
writer.write("DATA\n");
writer.write("0,0\n");
writer.write("\"\" \n");
// Write example data
if (exampleData != null) {
writer.write("-1,0\n");
writer.write("BOT\n");
for (Object cell : exampleData) {
if (cell instanceof Number) {
writer.write("0," + cell + "\n");
writer.write("V\n");
} else if (cell instanceof String) {
writer.write("1,0\n");
writer.write("\"" + cell + "\"\n");
}
}
writer.write("-1,0\n");
writer.write("EOD\n");
}
}
}
}
- The following is a JavaScript class for handling .DIF files. It includes methods to open (via asynchronous file reading), decode the header, print the properties to the console, and write a new .DIF file (using Node.js for file system access; adjust for browser if needed).
const fs = require('fs'); // For Node.js; remove for browser
class DIFHandler {
constructor(filename = null) {
this.filename = filename;
this.properties = {
version: null,
title: null,
num_vectors: null,
num_tuples: null,
labels: {},
comments: {},
sizes: {},
periodicities: {},
major_starts: {},
minor_starts: {},
true_lengths: {},
units: {},
display_units: {}
};
if (filename) {
this.read();
}
}
read() {
const content = fs.readFileSync(this.filename, 'utf8');
this.decode(content);
}
decode(content) {
const lines = content.split(/\r?\n/).map(line => line.trim());
let i = 0;
while (i < lines.length && lines[i] !== 'DATA') {
const topic = lines[i];
const [vector, numValue] = lines[i+1].split(',').map(Number);
const strValue = lines[i+2].replace(/^"(.*)"$/, '$1');
if (topic === 'TABLE') {
this.properties.version = numValue;
this.properties.title = strValue;
} else if (topic === 'VECTORS') {
this.properties.num_vectors = numValue;
} else if (topic === 'TUPLES') {
this.properties.num_tuples = numValue;
} else if (topic === 'LABEL') {
if (!this.properties.labels[vector]) this.properties.labels[vector] = [];
this.properties.labels[vector].push({ line: numValue, label: strValue });
} else if (topic === 'COMMENT') {
if (!this.properties.comments[vector]) this.properties.comments[vector] = [];
this.properties.comments[vector].push({ line: numValue, comment: strValue });
} else if (topic === 'SIZE') {
this.properties.sizes[vector] = numValue;
} else if (topic === 'PERIODICITY') {
this.properties.periodicities[vector] = numValue;
} else if (topic === 'MAJORSTART') {
this.properties.major_starts[vector] = numValue;
} else if (topic === 'MINORSTART') {
this.properties.minor_starts[vector] = numValue;
} else if (topic === 'TRUELENGTH') {
this.properties.true_lengths[vector] = numValue;
} else if (topic === 'UNITS') {
this.properties.units[vector] = strValue;
} else if (topic === 'DISPLAYUNITS') {
this.properties.display_units[vector] = strValue;
}
i += 3;
}
}
printProperties() {
console.log(this.properties);
}
write(outputFilename, newProperties, exampleData) {
if (newProperties) {
Object.assign(this.properties, newProperties);
}
let output = '';
if (this.properties.version !== null && this.properties.title !== null) {
output += 'TABLE\n';
output += `0,${this.properties.version}\n`;
output += `"${this.properties.title}"\n`;
}
if (this.properties.num_vectors !== null) {
output += 'VECTORS\n';
output += `0,${this.properties.num_vectors}\n`;
output += '""\n';
}
if (this.properties.num_tuples !== null) {
output += 'TUPLES\n';
output += `0,${this.properties.num_tuples}\n`;
output += '""\n';
}
// Add labels (example)
for (const [vector, labels] of Object.entries(this.properties.labels)) {
for (const label of labels) {
output += 'LABEL\n';
output += `${vector},${label.line}\n`;
output += `"${label.label}"\n`;
}
}
// Similarly for others (omitted)
output += 'DATA\n';
output += '0,0\n';
output += '""\n';
if (exampleData) {
output += '-1,0\n';
output += 'BOT\n';
for (const cell of exampleData) {
if (typeof cell === 'number') {
output += `0,${cell}\n`;
output += 'V\n';
} else if (typeof cell === 'string') {
output += '1,0\n';
output += `"${cell}"\n`;
}
}
output += '-1,0\n';
output += 'EOD\n';
}
fs.writeFileSync(outputFilename, output);
}
}
- The following is a C++ class (since standard C does not support classes natively) for handling .DIF files. It includes methods to open and read a file, decode the header, print the properties to the console, and write a new .DIF file with specified properties (using minimal example data for demonstration).
#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>
#include <map>
#include <string>
struct PropertyEntry {
int line;
std::string value;
};
class DIFHandler {
private:
std::string filename;
int version;
std::string title;
int num_vectors;
int num_tuples;
std::map<int, std::vector<PropertyEntry>> labels;
std::map<int, std::vector<PropertyEntry>> comments;
std::map<int, int> sizes;
std::map<int, int> periodicities;
std::map<int, int> major_starts;
std::map<int, int> minor_starts;
std::map<int, int> true_lengths;
std::map<int, std::string> units;
std::map<int, std::string> display_units;
public:
DIFHandler(const std::string& fn = "") : filename(fn), version(-1), num_vectors(-1), num_tuples(-1) {
if (!filename.empty()) {
read();
}
}
void read() {
std::ifstream file(filename);
if (!file.is_open()) {
std::cerr << "File not found." << std::endl;
return;
}
std::stringstream content;
content << file.rdbuf();
decode(content.str());
}
void decode(const std::string& content) {
std::istringstream iss(content);
std::string line;
std::vector<std::string> lines;
while (std::getline(iss, line)) {
lines.push_back(line);
}
for (size_t i = 0; i < lines.size() && lines[i] != "DATA"; i += 3) {
std::string topic = lines[i];
std::string part_line = lines[i + 1];
size_t comma_pos = part_line.find(',');
int vector = std::stoi(part_line.substr(0, comma_pos));
int num_value = std::stoi(part_line.substr(comma_pos + 1));
std::string str_value = lines[i + 2];
str_value = str_value.substr(1, str_value.size() - 2); // Remove quotes
if (topic == "TABLE") {
version = num_value;
title = str_value;
} else if (topic == "VECTORS") {
num_vectors = num_value;
} else if (topic == "TUPLES") {
num_tuples = num_value;
} else if (topic == "LABEL") {
labels[vector].push_back({num_value, str_value});
} else if (topic == "COMMENT") {
comments[vector].push_back({num_value, str_value});
} else if (topic == "SIZE") {
sizes[vector] = num_value;
} else if (topic == "PERIODICITY") {
periodicities[vector] = num_value;
} else if (topic == "MAJORSTART") {
major_starts[vector] = num_value;
} else if (topic == "MINORSTART") {
minor_starts[vector] = num_value;
} else if (topic == "TRUELENGTH") {
true_lengths[vector] = num_value;
} else if (topic == "UNITS") {
units[vector] = str_value;
} else if (topic == "DISPLAYUNITS") {
display_units[vector] = str_value;
}
}
}
void printProperties() {
std::cout << "version: " << version << std::endl;
std::cout << "title: " << title << std::endl;
std::cout << "num_vectors: " << num_vectors << std::endl;
std::cout << "num_tuples: " << num_tuples << std::endl;
// Print labels
std::cout << "labels: ";
for (const auto& pair : labels) {
std::cout << "vector " << pair.first << ": ";
for (const auto& entry : pair.second) {
std::cout << "{line: " << entry.line << ", label: " << entry.value << "} ";
}
}
std::cout << std::endl;
// Similarly for other maps (omitted for brevity; implement as needed)
}
void write(const std::string& output_filename, const std::map<std::string, std::string>& new_properties, const std::vector<std::string>& example_data) {
// Update properties if provided (simplified; parse new_properties as needed)
std::ofstream file(output_filename);
if (!file.is_open()) {
std::cerr << "Error opening output file." << std::endl;
return;
}
file << "TABLE\n";
file << "0," << version << "\n";
file << "\"" << title << "\"\n";
file << "VECTORS\n";
file << "0," << num_vectors << "\n";
file << "\"\"\n";
file << "TUPLES\n";
file << "0," << num_tuples << "\n";
file << "\"\"\n";
// Write labels example
for (const auto& pair : labels) {
for (const auto& entry : pair.second) {
file << "LABEL\n";
file << pair.first << "," << entry.line << "\n";
file << "\"" << entry.value << "\"\n";
}
}
// Similarly for others
file << "DATA\n";
file << "0,0\n";
file << "\"\"\n";
if (!example_data.empty()) {
file << "-1,0\n";
file << "BOT\n";
for (const auto& cell : example_data) {
// Assume string for simplicity
file << "1,0\n";
file << "\"" << cell << "\"\n";
}
file << "-1,0\n";
file << "EOD\n";
}
file.close();
}
};