Render CouchDB's new _time_seq response as a histogram

time_seq_histogram_mplib.py

#!/usr/bin/env python3

# Render _time_seq response as a histogram using matplotlib
# Run as:
#   http $DB/db/_time_seq | ~/scripts/time_seq_histogram_mplib.py

import json, sys
from datetime import datetime
import matplotlib.pyplot as plt
import matplotlib.dates as mdates

SECONDS_PER_DAY = 86400
BAR_COLOR = (0.8, 0.15, 0.16)

def load_data(infile):
    data = json.load(infile)
    time_seq = data.get('time_seq', {})
    for key in time_seq:
        node_data = time_seq[key]
        for node_key in node_data:
            return node_data[node_key]
    return []

def histogram(data):
    if not data:
        return
    tstamps = []
    counts = []
    for tstamp_str, count in data:
        try:
            dt = datetime.fromisoformat(tstamp_str.replace('Z', '+00:00'))
            tstamps.append(dt)
            counts.append(count)
        except:
            print(f"Warning: Could not parse timestamp: {tstamp_str}")
            continue
    if not tstamps:
        print("No valid timestamps found")
        return
    bar_widths = []
    for i in range(len(tstamps)):
        if i < len(tstamps) - 1:
            # matplotlib uses days for datetime
            dt = (tstamps[i+1] - tstamps[i]).total_seconds() / SECONDS_PER_DAY
            bar_widths.append(dt - 1200/SECONDS_PER_DAY)
        else:
            # Let's use 3h for last bin
            bar_widths.append(3*3600/SECONDS_PER_DAY)
    fig, ax = plt.subplots(figsize=(12, 6))
    ax.bar(tstamps, counts, width=bar_widths, align='edge', color=BAR_COLOR, alpha=0.7, edgecolor='black')
    ax.set_xticks(tstamps)
    ax.xaxis.set_major_formatter(mdates.DateFormatter('%m-%dT%Hh'))
    plt.xticks(rotation=-45, ha='left', fontsize=7)
    ax.grid(True, alpha=0.4, axis='y')
    ax.annotate('$Now$', xy=(0.97, 0), ha='left', va='top', xycoords='axes fraction', fontweight='bold', fontsize=9)
    plt.tight_layout()
    plt.show()

def main():
    try:
        if not sys.stdin.isatty():
            data = load_data(sys.stdin)
        else:
            print("Usage:")
            print("  cat <file_path> | python3 time_seq_histogram3.py")
            return
        if not data:
            return
        histogram(data)
    except FileNotFoundError as e:
        print(f"Error: File not found: {e}")
    except json.JSONDecodeError as e:
        print(f"Error: Invalid JSON format: {e}")
    except Exception as e:
        print(f"Error: {e}")

if __name__ == "__main__":
    main()