Merge pull request #35 from fastfloat/latex_table

script to generate LaTeX tables from our benchmark outputs

Author: lemire

scripts/README.md

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+## Creating LaTeX tables
+
+Prerequisite: You should be able to build and run the C++ benchmark. You need Python 3 on your system.
+
+Run your benchmark:
+
+```
+cmake -B build
+./build/benchmarks/benchmark -f data/canada.txt > myresults.txt
+```
+
+Process the raw output:
+
+```
+ ./scripts/latex_table.py myresults.txt
+```
+
+This will print out to std out the table. The numbers are already rounded to two significant digits,
+ready to be included in a scientific manuscript.

scripts/latex_table.py

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+#!/usr/bin/env python3
+
+import sys
+import re
+import argparse
+
+# Function to format a number to two significant digits
+def format_to_two_sig_digits(value):
+    if not isinstance(value, (int, float)) or value == 0:
+        return "N/A"
+    
+    # Handle negative numbers
+    is_negative = value < 0
+    abs_value = abs(value)
+
+    exponent = 0
+
+    while abs_value >= 100:
+        abs_value /= 10
+        exponent += 1
+    while abs_value < 10:
+        abs_value *= 10
+        exponent -= 1
+
+    # Round to two significant digits
+    abs_value = round(abs_value, 0)
+
+    # Format the number
+    if exponent >= 0 and exponent <= 4:
+        format = f"{'-' if is_negative else ''}{abs_value*10**exponent}"
+        format = format.replace(".0", "")
+        return format
+    elif exponent < 0 and exponent >= -4:
+        return f"{'-' if is_negative else ''}{abs_value*10**exponent:.1f}"
+    else:
+        return f"{'-' if is_negative else ''}{abs_value:.1f}e{exponent}"
+
+# Function to parse the raw input data
+def parse_input(data):
+    lines = data.splitlines()
+    parsed_data = []
+    current_entry = None
+
+    for line in lines:
+        line = line.strip()
+        # Skip empty lines or comments
+        if not line or line.startswith("#"):
+            continue
+
+        # Match lines that start a new entry (e.g., "just_string : 1365.92 MB/s ...")
+        match_entry = re.match(r"(\S+)\s*:\s*[\d.]+\s*MB/s", line)
+        if match_entry:
+            current_entry = {"name": match_entry.group(1)}
+            parsed_data.append(current_entry)
+        if not current_entry:
+            continue
+        # Match lines with ns/f
+        match_ns = re.search(r"([\d.]+)\s*ns/f", line)
+        if match_ns and current_entry:
+            current_entry["ns_per_float"] = float(match_ns.group(1))
+
+        # Match lines with instructions/float (i/f)
+        match_inst_float = re.search(r"([\d.]+)\s*i/f", line)
+        if match_inst_float and current_entry:
+            current_entry["inst_per_float"] = float(match_inst_float.group(1))
+
+        # Match lines with instructions/cycle (i/c)
+        match_inst_cycle = re.search(r"([\d.]+)\s*i/c", line)
+        if match_inst_cycle and current_entry:
+            current_entry["inst_per_cycle"] = float(match_inst_cycle.group(1))
+
+    # Filter out incomplete entries
+    return parsed_data
+
+# Function to generate LaTeX table
+def generate_latex_table(data):
+    latex_table = r"""
+\begin{tabular}{lccc}
+\toprule
+\textbf{Name} & \textbf{ns/f} & \textbf{instructions/float} & \textbf{instructions/cycle} \\
+\midrule
+"""
+
+    for entry in data:
+        name = entry["name"].replace("_", "\\_")  # Escape underscores for LaTeX
+        ns_per_float = format_to_two_sig_digits(entry['ns_per_float']) if 'ns_per_float' in entry else 'N/A'
+        inst_per_float = format_to_two_sig_digits(entry['inst_per_float']) if 'inst_per_float' in entry else 'N/A'
+        inst_per_cycle = format_to_two_sig_digits(entry['inst_per_cycle']) if 'inst_per_cycle' in entry else 'N/A'
+        latex_table += f"{name} & {ns_per_float} & {inst_per_float} & {inst_per_cycle} \\\\ \n"
+
+    latex_table += r"""\bottomrule
+\end{tabular}
+"""
+    return latex_table
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Generate LaTeX table from performance data")
+    parser.add_argument("file", nargs="?", help="Optional input file name (if not provided, reads from stdin)")
+    args = parser.parse_args()
+
+    # Read input data
+    if args.file:
+        try:
+            with open(args.file, "r") as f:
+                raw_input = f.read()
+        except FileNotFoundError:
+            print(f"Error: File '{args.file}' not found.", file=sys.stderr)
+            sys.exit(1)
+        except IOError as e:
+            print(f"Error reading file '{args.file}': {e}", file=sys.stderr)
+            sys.exit(1)
+    else:
+        raw_input = sys.stdin.read()
+    parsed_data = parse_input(raw_input)
+    latex_output = generate_latex_table(parsed_data)
+    print(latex_output)