在matplotlib中绘制2个词典

我有两本字典：dict1={‘牛肉’：10，‘家禽’：13，‘猪肉’：14，‘羔羊’：11}和dict2={‘牛肉’：3，‘家禽’：1，‘猪肉’：17，‘羔羊’：16}

我想绘制一个双条形图，使用字典键作为x轴值，并在y轴上使用相关值。我正在为此使用matplotlib。有人有任何信息吗？

matplotlib文档的一部分可能就是您要查找的内容。要绘制数据，需要从dict中提取x和y值，例如通过

dict.keys（）

和

dict.values（）

结果:

---

我想提出一个更一般的方法：如果我们有一个字典列表，会发生什么呢

In [89]: from random import randint, seed, shuffle
    ...: seed(20201213)
    ...: cats = 'a b c d e f g h i'.split() # categories
    ...: # List Of Dictionaries
    ...: lod = [{k:randint(5, 15) for k in shuffle(cats) or cats[:-2]} for _ in range(5)]
    ...: lod
Out[89]: 
[{'d': 14, 'h': 10, 'i': 13, 'f': 13, 'c': 5, 'b': 5, 'a': 14},
 {'h': 12, 'd': 5, 'c': 5, 'i': 11, 'b': 14, 'g': 8, 'e': 13},
 {'d': 8, 'a': 12, 'f': 7, 'h': 10, 'g': 10, 'c': 11, 'i': 12},
 {'g': 11, 'f': 8, 'i': 14, 'h': 11, 'a': 5, 'c': 7, 'b': 8},
 {'e': 11, 'h': 13, 'c': 5, 'i': 8, 'd': 12, 'a': 11, 'g': 11}]

正如您所看到的，键的顺序不同，字典也不包含所有可能的键

我们的第一步是找到一个键列表（

lok

），使用

set

理解，然后对键进行排序（是的，我们已经知道了键，但这里我们正在寻找一个通用的解决方案…）

两个列表中的元素数为

In [91]: nk, nd = len(lok), len(lod)

在这一点上，我们可以计算单个条的宽度，假设条组之间相距1个单位（因此

x=range（nk）

），并且我们在组之间留出1/3个单位，我们得到

In [92]: x, w = range(nk), 0.67/nd

我们已经准备好进行阴谋了

In [93]: import matplotlib.pyplot as plt
    ...: for n, d in enumerate(lod):
    ...:     plt.bar([ξ+n*w for ξ in x], [d.get(k, 0) for k in lok], w,
    ...:             label='dict %d'%(n+1))
    ...: plt.xticks([ξ+w*nd/2 for ξ in x], lok)
    ...: plt.legend();

---

让我们编写一个小函数

def plot_lod(lod, ws=0.33, ax=None, legend=True):
    """bar plot from the values in a list of dictionaries.

    lod: list of dictionaries,
    ws: optional, white space between groups of bars as a fraction of unity,
    ax: optional, the Axes object to draw into,
    legend: are we going to draw a legend?

    Return: the Axes used to plot and a list of BarContainer objects."""

    from matplotlib.pyplot import subplot
    from numpy import arange, nan

    if ax is None : ax = subplot()

    lok = sorted({k for d in lod for k in d})
    nk, nd = len(lok), len(lod)
    x, w = arange(nk), (1.0-ws)/nd

    lobars = [
        ax.bar(x+n*w, [d.get(k, nan) for k in lok], w, label='%02d'%(n+1))
        for n, d in enumerate(lod)
        ]
    ax.set_xticks(x+w*nd/2-w/2)
    ax.set_xticklabels(lok)
    if legend : ax.legend()
    return ax, lobars

使用上一个示例的数据，我们得到一个稍微不同的图

参见

In [93]: import matplotlib.pyplot as plt
    ...: for n, d in enumerate(lod):
    ...:     plt.bar([ξ+n*w for ξ in x], [d.get(k, 0) for k in lok], w,
    ...:             label='dict %d'%(n+1))
    ...: plt.xticks([ξ+w*nd/2 for ξ in x], lok)
    ...: plt.legend();

def plot_lod(lod, ws=0.33, ax=None, legend=True):
    """bar plot from the values in a list of dictionaries.

    lod: list of dictionaries,
    ws: optional, white space between groups of bars as a fraction of unity,
    ax: optional, the Axes object to draw into,
    legend: are we going to draw a legend?

    Return: the Axes used to plot and a list of BarContainer objects."""

    from matplotlib.pyplot import subplot
    from numpy import arange, nan

    if ax is None : ax = subplot()

    lok = sorted({k for d in lod for k in d})
    nk, nd = len(lok), len(lod)
    x, w = arange(nk), (1.0-ws)/nd

    lobars = [
        ax.bar(x+n*w, [d.get(k, nan) for k in lok], w, label='%02d'%(n+1))
        for n, d in enumerate(lod)
        ]
    ax.set_xticks(x+w*nd/2-w/2)
    ax.set_xticklabels(lok)
    if legend : ax.legend()
    return ax, lobars