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##Worth-seeing Python efficient data processing
Pandas is a very commonly used data processing tool in Python and is very convenient to use. It is built on the NumPy array structure, so many of its operations are written through the extension modules that come with NumPy or Pandas. These modules are written in Cython and compiled into C, and are executed on C, thus ensuring the processing speed. Today we will experience its power.mu1, sigma1 = 0, 0.1 mu2, sigma2 = 0.2, 0.2 n = 1000df = pd.DataFrame( { "a1": pd.np.random.normal(mu1, sigma1, n), "a2": pd.np.random.normal(mu2, sigma2, n), "a3": pd.np.random.randint(0, 5, n), "y1": pd.np.logspace(0, 1, num=n), "y2": pd.np.random.randint(0, 2, n), } )
1. Draw the average line
2. Mark the important points
import matplotlib.pyplot as plt ax = df.y1.plot() ax.axhline(6, color="red", linestyle="--") ax.axvline(775, color="red", linestyle="--") plt.show()We can also customize how many tables are displayed on a graph:
fig, ax = plt.subplots(2, 2, figsize=(14,7)) df.plot(x="index", y="y1", ax=ax[0, 0]) df.plot.scatter(x="index", y="y2", ax=ax[0, 1]) df.plot.scatter(x="index", y="a3", ax=ax[1, 0]) df.plot(x="index", y="a1", ax=ax[1, 1]) plt.show()
df[["a1", "a2"]].plot(bins=30, kind="hist") plt.show()It also allows multiple graphics to be drawn:
df[["a1", "a2"]].plot(bins=30, kind="hist", subplots=True) plt.show()Of course, generating a line chart is not a draw either:
df[['a1', 'a2']].plot(by=df.y2, subplots=True) plt.show()
df['ones'] = pd.np.ones(len(df)) m, c = pd.np.linalg.lstsq(df[['index', 'ones']], df['y1'], rcond=None)[0]Draw y and the fitted straight line based on the least squares result:
df['y'] = df['index'].apply(lambda x: x * m + c) df[['y', 'y1']].plot() plt.show()Thank you for reading, I hope you will benefit a lot. This article is reproduced from: https://blog.csdn.net/u010751000/article/details/106735872 python tutorial
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