Matplotlib的get_ticklabels不适用于自定义字符串标签

Question

我只想绘制“日期”中每隔50个项目作为x轴上的刻度。当我注释掉“ plt.xticks（xticks，dates）”行时，它工作正常（上图），但是当我尝试用实际的日期字符串替换数字时，它将所有日期而不是每第50个日期放入（下图）。

有人可以告诉我我在做什么错吗？谢谢！

import matplotlib.pyplot as plt
from datetime import datetime, date
import numpy as np

vals = [10, 11, 10, 6, 7, 4, 4, 6, 2, 3, 11, 11, 8, 8, 6, 9, 8, 8, 6, 6, 5, 2, 3, 5, 2, 3, 5, 6, 4, 6, 4, 1, 3, 4, 5, 5, 5, 7, 4, 4, 3, 5, 4, 5, 6, 4, 5, 3, 2, 4, 4, 4, 2, 2, 1, 7, 4, 8, 5, 3, 1, 3, 4, 6, 3, 7, 3, 3, 4, 5, 8, 6, 4, 2, 2, 4, 3, 2, 6, 4, 9, 6, 6, 5, 14, 17, 13, 11, 5, 7, 11, 7, 9, 6, 3, 7, 5, 4, 5, 7, 5, 4, 3, 4, 4, 2, 1, 2, 2, 2, 1, 1, 3, 4, 2, 2, 1, 2, 2, 2, 1, 3, 1, 1, 2, 1, 1, 2, 5, 1, 2, 1, 1, 1, 2, 2, 1, 1, 1, 2, 1, 2, 4, 5, 4, 3, 3, 2, 4, 3, 3, 3, 2, 1, 1, 3, 5, 4, 4, 4, 5, 6, 5, 3, 2, 3, 2, 2, 2, 2, 1, 1, 1, 2, 3, 2, 2, 3, 3, 2, 2, 2, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 3, 8, 1]

dates =['05/01/2018', '05/02/2018', '05/03/2018', '05/04/2018', '05/05/2018', '05/06/2018', '05/07/2018', '05/08/2018', '05/09/2018', '05/10/2018', '05/11/2018', '05/12/2018', '05/13/2018', '05/14/2018', '05/15/2018', '05/16/2018', '05/17/2018', '05/18/2018', '05/19/2018', '05/20/2018', '05/21/2018', '05/22/2018', '05/23/2018', '05/24/2018', '05/25/2018', '05/26/2018', '05/27/2018', '05/28/2018', '05/29/2018', '05/30/2018', '05/31/2018', '06/01/2018', '06/02/2018', '06/03/2018', '06/04/2018', '06/05/2018', '06/06/2018', '06/07/2018', '06/08/2018', '06/09/2018', '06/10/2018', '06/11/2018', '06/12/2018', '06/13/2018', '06/14/2018', '06/15/2018', '06/16/2018', '06/17/2018', '06/18/2018', '06/19/2018', '06/20/2018', '06/21/2018', '06/22/2018', '06/23/2018', '06/24/2018', '06/25/2018', '06/26/2018', '06/27/2018', '06/28/2018', '06/29/2018', '06/30/2018', '07/01/2018', '07/02/2018', '07/03/2018', '07/04/2018', '07/05/2018', '07/06/2018', '07/07/2018', '07/08/2018', '07/09/2018', '07/10/2018', '07/11/2018', '07/12/2018', '07/13/2018', '07/14/2018', '07/15/2018', '07/16/2018', '07/17/2018', '07/18/2018', '07/19/2018', '07/20/2018', '07/21/2018', '07/22/2018', '07/23/2018', '07/24/2018', '07/25/2018', '07/26/2018', '07/27/2018', '07/28/2018', '07/29/2018', '07/30/2018', '07/31/2018', '08/01/2018', '08/02/2018', '08/03/2018', '08/04/2018', '08/05/2018', '08/06/2018', '08/07/2018', '08/08/2018', '08/09/2018', '08/10/2018', '08/11/2018', '08/12/2018', '08/13/2018', '08/14/2018', '08/15/2018', '08/16/2018', '08/17/2018', '08/18/2018', '08/19/2018', '08/21/2018', '08/22/2018', '08/23/2018', '08/24/2018', '08/25/2018', '08/26/2018', '08/27/2018', '08/28/2018', '08/29/2018', '08/30/2018', '08/31/2018', '09/01/2018', '09/06/2018', '09/07/2018', '09/08/2018', '09/09/2018', '09/10/2018', '09/11/2018', '09/12/2018', '09/13/2018', '09/14/2018', '09/15/2018', '09/16/2018', '09/17/2018', '09/18/2018', '09/19/2018', '09/20/2018', '09/21/2018', '09/22/2018', '09/23/2018', '09/24/2018', '09/25/2018', '09/26/2018', '09/27/2018', '09/28/2018', '09/29/2018', '09/30/2018', '10/01/2018', '10/02/2018', '10/03/2018', '10/04/2018', '10/05/2018', '10/06/2018', '10/07/2018', '10/08/2018', '10/09/2018', '10/10/2018', '10/11/2018', '10/12/2018', '10/13/2018', '10/14/2018', '10/15/2018', '10/16/2018', '10/17/2018', '10/18/2018', '10/19/2018', '10/20/2018', '10/21/2018', '10/22/2018', '10/23/2018', '10/24/2018', '10/25/2018', '10/28/2018', '10/29/2018', '10/30/2018', '10/31/2018', '11/01/2018', '11/02/2018', '11/03/2018', '11/04/2018', '11/05/2018', '11/06/2018', '11/07/2018', '11/08/2018', '11/09/2018', '11/10/2018', '11/11/2018', '11/12/2018', '11/13/2018', '11/14/2018', '11/15/2018', '11/16/2018', '11/22/2018', '11/23/2018', '11/25/2018', '11/26/2018', '11/27/2018', '11/29/2018', '12/01/2018', '12/02/2018', '12/05/2018']
    xticks = np.arange(len(vals))

    ax = plt.axes()
    ax.bar(xticks,vals)
    plt.xticks(rotation=90)
    plt.xticks(xticks, dates)
    for label in ax.xaxis.get_ticklabels()[::50]:
        label.set_visible(True)

    plt.show()

Answer 1

以下方法应该起作用：

ax = plt.axes()

pos = np.arange(len(vals))
ax.bar(pos, vals)

ax.set_xticks(pos[::50])
ax.set_xticklabels(np.array(dates)[::50], rotation=90)

Answer 2

您尝试设置每第50个可见标签。但是其他所有内容仍然可见，因此所有内容以及您设置的内容均可见。当然，您可以设置一些可见的；但是也许更好的解决方案是根本不创建标签？

要在第50个条目上打勾并标记，您可以对打勾和标签列表进行切片。

import matplotlib.pyplot as plt
from datetime import datetime, date
import numpy as np

vals = [10, 11, ....]
dates =['05/01/2018', '05/02/2018', ....]
xticks = np.arange(len(vals))

ax = plt.axes()
ax.bar(xticks,vals)

plt.xticks(xticks[::50], dates[::50], rotation=90)

plt.show()

但是请注意，仅将日期绘制为日期时间会自动为您提供非常好的格式。

import matplotlib.pyplot as plt
from datetime import datetime

vals = [10, 11, ..., 1]
dates =['05/01/2018', '05/02/2018', ..., '12/05/2018']
dates = [datetime.strptime(s, "%m/%d/%Y") for s in dates]

ax = plt.axes()
ax.bar(dates,vals)

plt.show()