python 画柱状图

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数据统计是科研中很重要的一部分，所以我们老师老是让我搞各种数据可视化的工作…………

首先要安装matplotlib

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pip install matplotlib

基本柱状图（使用hist函数）

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import matplotlib.pyplot as plt
import numpy as np

# Learn about API authentication here: https://plot.ly/python/getting-started
# Find your api_key here: https://plot.ly/settings/api

gaussian_numbers = np.random.randn(1000)
plt.hist(gaussian_numbers)
plt.title("Gaussian Histogram")
plt.xlabel("Value")
plt.ylabel("Frequency")

plt.show()

多个数据集的柱状图

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import pylab as plt
import plotly.plotly as py

fig = plt.figure()

x = 200 + 25*plt.randn(1000)
y = 150 + 25*plt.randn(1000)
n, bins, patches = plt.hist([x, y])
plt.show()

概率密度函数

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import numpy as np
import matplotlib.mlab as mlab
import matplotlib.pyplot as plt
import plotly.plotly as py  # tools to communicate with Plotly's server

fig = plt.figure()

# example data
mu = 100 # mean of distribution
sigma = 15 # standard deviation of distribution
x = mu + sigma * np.random.randn(10000)

num_bins = 50
# the histogram of the data
n, bins, patches = plt.hist(x, num_bins, normed=1, facecolor='green', alpha=0.5)
# add a 'best fit' line
y = mlab.normpdf(bins, mu, sigma)
plt.plot(bins, y, 'r--')
plt.xlabel('Smarts')
plt.ylabel('Probability')

# Tweak spacing to prevent clipping of ylabel
plt.subplots_adjust(left=0.15)

plt.show()

https://plot.ly/matplotlib/histograms/
http://matplotlib.org/api/pyplot_api.html