From 9e8aec2a6df4d402d87445e90843bedb550668e3 Mon Sep 17 00:00:00 2001
From: Dan Howe <d.howe@wrl.unsw.edu.au>
Date: Thu, 12 May 2022 19:51:06 +0200
Subject: [PATCH] Add 'generate_slr_timeseries.py'

---
 slr/generate_slr_timeseries.py | 105 +++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 slr/generate_slr_timeseries.py

diff --git a/slr/generate_slr_timeseries.py b/slr/generate_slr_timeseries.py
new file mode 100644
index 0000000..8c85efc
--- /dev/null
+++ b/slr/generate_slr_timeseries.py
@@ -0,0 +1,105 @@
+import os
+import re
+import numpy as np
+import pandas as pd
+from scipy import stats
+import matplotlib.pyplot as plt
+
+START_YEAR = 2020
+END_YEAR = 2100
+
+n_runs = 100000
+
+df = pd.read_csv('cauchy-values.csv', index_col=0)
+years = np.arange(START_YEAR, END_YEAR + 1)
+
+# Squeeze distribution to zero in 2020
+df.loc[2020, 'scale'] = 0.0001
+df.loc[2020, 'min'] = df.loc[2020, 'loc'] - 0.0001
+df.loc[2020, 'max'] = df.loc[2020, 'loc'] + 0.0001
+
+# Interpolate intermediate values
+df = df.reindex(years).interpolate(method='cubic')
+
+# Prepare array for SLR values
+slr = np.zeros([len(years), n_runs], dtype=float)
+
+for i, (year, row) in enumerate(df.iterrows()):
+    # Get probability distribution
+    dist = stats.cauchy(loc=row['loc'], scale=row['scale'])
+
+    # Generate random samples
+    for factor in range(2, 10):
+        s_raw = dist.rvs(n_runs * factor)
+
+        # Take first samples within valid range
+        s = s_raw[(s_raw > row['min']) & (s_raw < row['max'])]
+
+        if len(s) > n_runs:
+            break  # Success
+        else:
+            pass  # We need more samples, so try larger factor
+
+    # Add the requried number of samples
+    slr[i] = s[:n_runs]
+
+# Sort each row to make SLR trajectories smooth
+slr = np.sort(slr, axis=1)
+
+# Randomise run order (column-wise)
+slr = np.random.permutation(slr.T).T
+
+# Set first year to zero
+slr[0, :] = df.loc[2020, 'loc']
+
+# Plot first few trajectories
+if True:
+    fig, ax = plt.subplots(1,
+                           3,
+                           figsize=(12, 5),
+                           sharey=True,
+                           gridspec_kw={
+                               'wspace': 0.05,
+                               'width_ratios': [3, 1, 1]
+                           })
+
+    ax[0].plot(years, slr[:, :100], c='#444444', lw=0.2)
+    ax[1].hist(slr[-1, :],
+               bins=100,
+               fc='#cccccc',
+               ec='#aaaaaa',
+               orientation='horizontal')
+
+    i = len(years) - 1
+    dff = df.T.loc['5':'95', years[i]]
+    ax[2].hist(
+        slr[i, :],
+        bins=100,
+        fc='#cccccc',
+        ec='#aaaaaa',
+        orientation='horizontal',
+        cumulative=True,
+    )
+    ax[2].plot(dff.index.astype(int) / 100 * n_runs,
+               dff.values,
+               'o',
+               c='C3',
+               label='IPCC AR6 data')
+
+    ax[0].set_xlim(right=years[i])
+
+    ax[0].set_title(f'SLR trajectories\n(first 100 out of {n_runs:,} runs)')
+    ax[1].set_title(f'Probability\ndistribution\nin year {years[i]}')
+    ax[2].set_title(f'Cumulative\ndistribution\nin year {years[i]}')
+    ax[0].set_ylabel('SLR (m)', labelpad=10)
+
+    ax[2].legend()
+
+    ax[0].spines['top'].set_visible(False)
+    ax[0].spines['right'].set_visible(False)
+
+    for a in ax[1:]:
+        a.spines['top'].set_visible(False)
+        a.spines['right'].set_visible(False)
+        a.spines['bottom'].set_visible(False)
+        a.xaxis.set_visible(False)