Question

我有以下数据样本为x，y对，x和y都是Unix时间戳：

1354648326,1354648326
1354649456,1371775551
1354649664,1429649819
1354649667,1429644021
1354649683,1356976159
1354649767,1441369794
1354649863,1414467362
1354650486,1366297316
1354650757,1456962664
1354650789,1359398128
1354651552,1354656458
1354651555,1368631443
1354651591,1456420412
1354651616,1354651616
1354651715,1444573208
1354652048,1454443352
1354652382,1394722546
1354652687,1355993864
1354653448,1387378662
1354653731,1396094300
1354653769,1417765024
1354654110,1457230519
1354654111,1452854788
1354654179,1423877890
1354654266,1355148505
1354654374,1446848232
1354654374,1456864004
1354654615,1355858928
1354654700,1456945892
1354654707,1456265183
1354654744,1442939141
1354654747,1388436654
1354654771,1449799848
1354654775,1355177773
1354654808,1456857861
1354654809,1411369798
1354654855,1355934384
1354654915,1457100468
1354654962,1388784204
1354655085,1454446403
1354655219,1364196550
1354655232,1387214819
1354655262,1377170885
1354655264,1369689630
1354655289,1388750388
1354655389,1387387305
1354655434,1389255185
1354655436,1387165968
1354655592,1374369153
1354655661,1456912753
1354655811,1354718201
1354655889,1426675579
1354656139,1420486774

我希望将其绘制为散点图，但没有在x和y轴上显示的丑陋时间戳格式。相反，我想在轴上绘制日期（格式为YYYY-MM-DD或任何其他可读格式），并显示3个月差异。

我有以下代码：

ax.set_xticklabels(getLabels(s,t),rotation=20)

其中getLabels(s,t)定义为：

def getLabels(s,t): #s and t are unix time stamps
    labels =[]
    for x in pd.date_range(start=s, end=t, freq='3M'):
        labels.append(str(x).replace(" 00:00:00",""))
    print labels
    return labels

并返回类似的内容：

['2012-06-30', '2012-09-30', '2012-12-31', '2013-03-31', '2013-06-30', '2013-09-30', '2013-12-31', '2014-03-31', '2014-06-30', '2014-09-30', '2014-12-31', '2015-03-31', '2015-06-30', '2015-09-30', '2015-12-31', '2016-03-31']
['2012-06-30', '2012-09-30', '2012-12-31', '2013-03-31', '2013-06-30', '2013-09-30', '2013-12-31', '2014-03-31', '2014-06-30', '2014-09-30', '2014-12-31', '2015-03-31', '2015-06-30', '2015-09-30', '2015-12-31', '2016-03-31']

现在，问题是x轴刻度标签没有像上一个日期数组那样完全显示，相反，它只显示前6个日期（从2012-09-30开始到2013-结束） 12-31）

有什么问题？

Answer 1

您的问题是您的图表只有五个刻度，因此它只能显示五个标签。如果要显示所有标签，则需要确保具有相同数量的刻度。

我没有安装pandas，无论如何，没有完整的数据，所以无法重新创建标签。我只是复制了你提供的标签列表。我还'反向设计'了min＆amp;标签的x轴最大值（以便数据在正确的位置绘制）。

这一行：ax.xaxis.set_ticks(np.arange(min_x, max_x, int((max_x-min_x)/len(labels)))) 确保您具有与标签相同的刻度数。

请注意，我还更改了标签的水平对齐方式，以便即使在压扁时，仍然可以清楚标签对应的标记。这片数据似乎绘制在正确的位置，所以我很确定标签位于正确的位置。

（显然y轴可以用同样的方式处理）

import matplotlib.pyplot as plt
import numpy as np
import time
import datetime

labels =['2012-06-30', '2012-09-30', '2012-12-31', '2013-03-31',
         '2013-06-30', '2013-09-30', '2013-12-31', '2014-03-31',
         '2014-06-30', '2014-09-30', '2014-12-31', '2015-03-31',
         '2015-06-30', '2015-09-30', '2015-12-31', '2016-03-31']
x = []
y = []
with open('data.txt','r') as myfile:
    for line in myfile:
        _x, _y = line.strip().split(',')
        x.append(int(_x))
        y.append(int(_y))

min_x = int(time.mktime(datetime.datetime.strptime('2012-06-30','%Y-%m-%d').timetuple()))
max_x = int(time.mktime(datetime.datetime.strptime('2016-03-31','%Y-%m-%d').timetuple()))

print (datetime.datetime.fromtimestamp(min(x)).strftime('%Y-%m-%d')) 
# Confirm that we are plotting in the right place for this sample

fig = plt.figure()
ax = fig.add_subplot(1,1,1)
ax.set_xlim(min_x, max_x)
ax.xaxis.set_ticks(np.arange(min_x, max_x, int((max_x-min_x)/len(labels))))
ax.set_xticklabels(labels, rotation=20, horizontalalignment = 'right')
ax.scatter(x,y)
plt.show()

Answer 2

x轴数据的限制仅从2012-12-05 06:12:06到2012-12-05 08:22:19。您必须扩展日期范围。

但是，您可以使用此代码每3个月设置一次x轴刻度：

import matplotlib.pyplot as plt
from itertools import izip
import datetime
import numpy as np
import pandas as pd

def grouped(iterable, n):
    return izip(*[iter(iterable)]*n)

def getLabels(s,t):
    labels =[]
    for x in pd.date_range(start=s, end=t, freq='3M'):
        labels.append(x.strftime("%Y-%m-%d"))
    print labels
    return labels

arr = [1354648326,1354648326,
1354649456,1371775551,
...
1354655889,1426675579,
1354656139,1420486774]

# convert timestamps to datetime objects
X = list()
Y = list()
for x, y in grouped(arr, 2):
    X.append(datetime.datetime.fromtimestamp(x))
    Y.append(datetime.datetime.fromtimestamp(y))

# range of X list is only one day: 2012-12-05
# you have to enlarge data of X
print np.min(X),np.max(X)

# sample data
data = np.random.uniform(-10, 10, size=len(X)*len(Y))

# plot
plt.scatter(X, Y, s = data)
ax = plt.gca()
# set limits for X-axis
ax.set_xlim([np.min(X),np.max(X)])
# generate labels
xlabels = getLabels(np.min(X),np.max(X))
# set ticks and labels
ax.set_xticks(xlabels)
ax.set_xticklabels(xlabels,rotation=20)

plt.show()

如果我扩展x轴限制，我会在你的数据上得到类似的东西：

...
# plot
plt.scatter(X, Y, s = data)
ax = plt.gca()
# set limits for X-axis
xmin = datetime.datetime(2012,1,1,0,0,0) # np.min(X)
xmax = xmin + datetime.timedelta(days = 360) # np.max(X)
ax.set_xlim([xmin, xmax])
# generate labels every 3 month
xlabels = getLabels(xmin, xmax)
# set ticks and labels
ax.set_xticks(xlabels)
ax.set_xticklabels(xlabels,rotation=20)
plt.show()

如果您想要更复杂的日期时间刻度标签，请阅读此answer。

控制x刻度日期值

2 个答案: