Neptune & SkachatPro
SkachatPro SkachatPro
Hey Neptune, I’ve been tinkering with some real‑time tide‑prediction algorithms—mind if I run them past you? I think your ancient knowledge could really help tweak the models.
Neptune Neptune
Neptune: Of course, let me dive into your code and see how the currents whisper through those equations. Share the details, and we’ll see if the ancient tides can fine‑tune your models.
SkachatPro SkachatPro
Here’s the core of the tide‑prediction routine I’ve wrapped up in Python. It pulls the last 24‑hour sea‑level record from the local buoy, normalises it, then runs a quick FFT to extract the dominant frequencies. After that I feed those into a simple sinusoidal model and interpolate for the next few hours. Feel free to point out any inefficiencies or let me know if you’d prefer a vectorised approach or a different library. ```python import numpy as np import pandas as pd from scipy.fft import rfft, rfftfreq # Load the raw sea‑level data (timestamp, height in cm) df = pd.read_csv('buoy_24h.csv', parse_dates=['timestamp']) heights = df['height_cm'].values times = df['timestamp'].values # Normalise by removing the mean and scaling to unit variance norm_heights = (heights - heights.mean()) / heights.std() # Compute the FFT n = len(norm_heights) freqs = rfftfreq(n, d=1/(24*60)) # 1 sample per minute fft_vals = rfft(norm_heights) # Identify the top 3 peaks (excluding the zero‑frequency component) peak_idx = np.argsort(np.abs(fft_vals[1:]))[-3:] + 1 peak_freqs = freqs[peak_idx] peak_amps = np.abs(fft_vals[peak_idx]) # Build a predictive model: sum of sinusoids def predict_tide(future_minutes): future_times = np.arange(future_minutes) pred = np.zeros_like(future_times, dtype=float) for amp, freq in zip(peak_amps, peak_freqs): pred += amp * np.sin(2 * np.pi * freq * future_times) # Reverse normalisation pred = pred * heights.std() + heights.mean() return pred # Example: predict the next 120 minutes future_pred = predict_tide(120) print(future_pred) ``` If you’re worried about the FFT resolution or want to incorporate a more robust physical model (like the M2 and S2 constituents), just let me know.
Neptune Neptune
Neptune: Your routine looks solid for a quick pass, but a few things could smooth it out. First, use the actual timestamps to set the sample spacing instead of hard‑coding 1 minute; if the buoy ever drops a sample, your FFT will drift. Second, normalising by std can blow up if the data is flat—add a small epsilon to guard against divide‑by‑zero. Third, you might want to keep the amplitude phase information; sin alone loses the offset, so adding a cosine term or using the complex FFT result can give you the correct phase. Finally, if you’re aiming for longer horizons, consider pulling in known tidal constituents like M2 or S2; they’re the ocean’s own beat, and adding them to your model will tighten the fit. Keep tinkering, the sea will reward you.
SkachatPro SkachatPro
Neptune, thanks for the pointers – all of them make sense. I’ll adjust the sampling to the real timestamps, add an epsilon for the std guard, and keep the complex FFT so I can recover both sine and cosine components. Adding the M2 and S2 constituents will give the model a solid foundation for multi‑day forecasts. I’ll push the updated script up to the repo and drop you a link once it’s ready to test. Keep those suggestions coming; the ocean doesn’t care how much you tweak it.
Neptune Neptune
Neptune: That sounds like a solid plan. Once you’ve added the M2 and S2, you might also look at the semi‑diurnal S1 component; it can catch some of the finer swell patterns. When you’re ready, share the link and we’ll see how the tides behave. The sea never forgets the ones who listen.
SkachatPro SkachatPro
Here’s the updated repo: https://github.com/skachatpro/tide‑model‑v2 I’ve added the M2, S2, and S1 constituents, and fixed the timestamp spacing and normalisation guard. Take a look, tweak as you see fit, and let me know how the predictions line up with the real tide data. Happy testing!
Neptune Neptune
Neptune: I can’t pull the repo right now, but the changes you described should tighten the fit. A quick sanity check is to compute the residuals against observed tide levels and plot a histogram; if it’s centered near zero with a narrow spread, you’re on track. Also try a simple 24‑hour rolling cross‑validation: train on one day, predict the next, and compute RMSE. That’ll give you a feel for how well the M2, S2, and S1 capture the real waves. Keep tweaking the phase offsets if you notice systematic shifts. Happy tides!