回帰分析

spring.py

import matplotlib.pyplot as plt
import pandas as pd
import numpy as np

f = open('springData.txt')
f.readline()

df = pd.read_csv(f, header=None, names=('dist', 'mass'), delimiter=' ')[:-6]
df['force'] = df['mass'] * 9.81

# FYI: https://ja.stackoverflow.com/questions/38755/matplotlib%E3%81%A7%E6%8F%8F%E7%94%BB%E3%81%97%E3%81%9F%E6%95%A3%E5%B8%83%E5%9B%B3%E3%81%AB%E7%B7%9A%E5%BD%A2%E5%9B%9E%E5%B8%B0%E7%9B%B4%E7%B7%9A%E3%82%92%E8%BF%BD%E5%8A%A0%E3%81%99%E3%82%8B%E6%96%B9%E6%B3%95
# 1-degree
#a, b = np.polyfit(df['force'], df['dist'], 1)
#df['fit'] = a * df['force'] + b

# 3-degree
fit = np.polyfit(df['force'], df['dist'], 3)
df['fit'] = np.polyval(fit, df['force'])

ax = df.plot.scatter(x='force', y='dist')
df.plot(x='force', y='fit', color='black', ax=ax)
plt.show()

springData.txt

Distance (m) Mass (kg)
0.0865 0.1
0.1015 0.15
0.1106 0.2
0.1279 0.25
0.1892 0.3
0.2695 0.35
0.2888 0.4
0.2425 0.45
0.3465 0.5
0.3225 0.55
0.3764 0.6
0.4263 0.65
0.4562 0.7
0.4502 0.75
0.4499 0.8
0.4534 0.85
0.4416 0.9
0.4304 0.95
0.437 1.0