Spin_efficiency.py

query = '''
SELECT pitch_type,release_speed,release_pos_x,release_pos_z,pitcher,pfx_x,pfx_z,plate_x,plate_z,balls,strikes,
vx0,vy0,vz0,ax,ay,az,release_spin_rate,release_extension,description


FROM statcast_2018
    WHERE  release_speed >= 0

'''

pitch_stat = pd.read_sql(query,engine)

c0 = 5.153E-03

pitch_stat['yR'] = 60-pitch_stat.release_extension
pitch_stat['tR'] = (-pitch_stat.vy0 - (pitch_stat.vy0**2-2*pitch_stat.ay*(50-pitch_stat.yR))**0.5)/pitch_stat.ay
pitch_stat['vxR'] = pitch_stat.vx0 + pitch_stat.ax * pitch_stat.tR
pitch_stat['vyR'] = pitch_stat.vy0 + pitch_stat.ay * pitch_stat.tR
pitch_stat['vzR'] = pitch_stat.vz0 + pitch_stat.az * pitch_stat.tR
pitch_stat['dv0'] = pitch_stat.release_speed - (pitch_stat.vxR**2+pitch_stat.vyR**2+pitch_stat.vzR**2)**0.5/1.467
pitch_stat['tf'] = (-pitch_stat.vyR-(pitch_stat.vyR**2-2*pitch_stat.ay*(pitch_stat.yR-17/12))**0.5)/pitch_stat.ay

pitch_stat['x_mvt'] = pitch_stat.plate_x - pitch_stat.release_pos_x - (pitch_stat.vxR/pitch_stat.vyR)*(17/12-pitch_stat.yR)
pitch_stat['z_mvt'] = pitch_stat.plate_z - pitch_stat.release_pos_z - (pitch_stat.vzR/pitch_stat.vyR)*(17/12-pitch_stat.yR) + 0.5*32.174*pitch_stat.tf**2

pitch_stat['vxbar'] = (2*pitch_stat.vxR+pitch_stat.ax*pitch_stat.tf)/2
pitch_stat['vybar'] = (2*pitch_stat.vyR+pitch_stat.ay*pitch_stat.tf)/2
pitch_stat['vzbar'] = (2*pitch_stat.vzR+pitch_stat.az*pitch_stat.tf)/2
pitch_stat['vbar'] = (pitch_stat.vxbar**2+pitch_stat.vybar**2+pitch_stat.vzbar**2)**0.5


pitch_stat['adrag'] = -(pitch_stat.ax*pitch_stat.vxbar+pitch_stat.ay*pitch_stat.vybar+(pitch_stat.az+32.174)*pitch_stat.vzbar)/pitch_stat.vbar
pitch_stat['Cd'] = pitch_stat.adrag/(c0*pitch_stat.vbar**2)

pitch_stat['amagx'] = pitch_stat.ax+pitch_stat.adrag*pitch_stat.vxbar/pitch_stat.vbar
pitch_stat['amagy'] = pitch_stat.ay+pitch_stat.adrag*pitch_stat.vybar/pitch_stat.vbar
pitch_stat['amagz'] = pitch_stat.az+pitch_stat.adrag*pitch_stat.vzbar/pitch_stat.vbar+32.174
pitch_stat['amag'] = (pitch_stat.amagx**2+pitch_stat.amagy**2+pitch_stat.amagz**2)**0.5

pitch_stat['Mx'] = 0.5*pitch_stat.amagx*pitch_stat.tf**2*12
pitch_stat['Mz'] = 0.5*pitch_stat.amagz*pitch_stat.tf**2*12

pitch_stat['Cl'] = pitch_stat.amag/(c0*pitch_stat.vbar**2)
pitch_stat['S'] = 0.4*pitch_stat.Cl/(1-2.32*pitch_stat.Cl)

pitch_stat['spinT'] = 78.92*pitch_stat.S*pitch_stat.vbar
pitch_stat['spinTX'] = pitch_stat.spinT*(pitch_stat.vybar*pitch_stat.amagz-pitch_stat.vzbar*pitch_stat.amagy)/(pitch_stat.amag*pitch_stat.vbar)
pitch_stat['spinTY'] = pitch_stat.spinT*(pitch_stat.vzbar*pitch_stat.amagx-pitch_stat.vxbar*pitch_stat.amagz)/(pitch_stat.amag*pitch_stat.vbar)
pitch_stat['spinTZ'] = pitch_stat.spinT*(pitch_stat.vxbar*pitch_stat.amagy-pitch_stat.vybar*pitch_stat.amagx)/(pitch_stat.amag*pitch_stat.vbar)

pitch_stat['spin_check'] = (pitch_stat.spinTX**2+pitch_stat.spinTY**2+pitch_stat.spinTZ**2)**0.5-pitch_stat.spinT

pitch_stat['phi'] = np.arctan2(pitch_stat.amagz,pitch_stat.amagx)*180/math.pi
pitch_stat['phi'] = pitch_stat['phi'] + pitch_stat['amagz'].apply(lambda x: 360 if x < 0 else 0)
pitch_stat['spin_eff'] = pitch_stat.spinT/pitch_stat.release_spin_rate

pitch_stat['flag'] = pitch_stat['description'].apply(lambda x: 1 if x == 'swinging_strike' else 0)