From e08ebd1d645b4ec1a9ab54a008fde45f8fe8029c Mon Sep 17 00:00:00 2001
From: Sander Roosendaal <roosendaalsander@gmail.com>
Date: Mon, 9 Nov 2020 19:16:21 +0100
Subject: [PATCH] getfastest (distance)

---
 rowers/datautils.py | 51 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/rowers/datautils.py b/rowers/datautils.py
index a9610e99..dda402c0 100644
--- a/rowers/datautils.py
+++ b/rowers/datautils.py
@@ -364,3 +364,54 @@ def getmaxwattinterval(tt,ww,i):
         deltat = 0
 
     return deltat,wmax
+
+def getfastest(df,thedistance):
+    tt = df['time'].copy()
+    dd = df['cumdist'].copy()
+
+    tmax = tt.max()
+
+    if tmax > 500000:
+        newlen=int(tmax/2000.)
+        newt = np.arange(newlen)*tmax/float(newlen)
+        deltat = newt[1]-newt[0]
+    else:
+        newt = np.arange(0,tmax,10.)
+        deltat = 10.
+
+    dd = griddata(tt.values,
+                  dd.values,newt,method='linear',rescale=True)
+
+    tt = pd.Series(newt)
+    dd = pd.Series(dd)
+
+    G = pd.concat([pd.Series([0]),dd])
+    h = np.mgrid[0:len(tt)+1:1,0:len(tt)+1:1]
+    distances = pd.DataFrame(h[1]-h[0])
+    ones = 1+np.zeros(len(G))
+    Ghor = np.outer(ones,G)
+    Gver = np.outer(G,ones)
+    Gdif = Ghor-Gver
+    Gdif = np.tril(Gdif.T).T
+    Gdif = pd.DataFrame(Gdif)
+    F = Gdif
+
+    F.fillna(inplace=True,method='ffill',axis=1)
+    F.fillna(inplace=True,value=0)
+
+    restime = []
+    distance = []
+
+    for i in np.arange(0,len(tt)+1,1):
+        restime.append(deltat*i)
+        cp = np.diag(F,i).max()
+        distance.append(cp)
+
+    distance[0] = distance[1]
+
+    restime = np.array(restime)
+    distance = np.array(distance)
+
+    d2 = griddata(distance,restime,[thedistance],method='linear',rescale=True)
+
+    return d2[0]/1000.