Visualize.py 文件源码

def scatter_crimes_population():
    """creates a scatter plot using the values of Population and Crimes Per 100000.
    iterates through the database and reads all the data in the given headers and creates plots for each data point
    """
    x = df["Number of Crimes"].values
    y = df["Population"].values
    assert len(x) == len(y)
    df["Crimes Per 100000"] = np.array([(x[i] / y[i]) * 100000.0 for i in range(len(x))], dtype="float32")

    ax = df.plot.scatter(y="Population", x="Crimes Per 100000")

    for index, row in df.iterrows():
        ax.annotate(row["Community Name"], (row["Crimes Per 100000"], row["Population"]),
                    size=7,
                    color='darkslategrey')

    x = df["Crimes Per 100000"].values
    y = df["Population"].values

    m, b = np.polyfit(x, y, 1)
    line = plt.plot(x, m * x + b, 'b--')
    plt.setp(line, color='orange', alpha=0.5, linewidth=2.0)
    plt.show()