用时间轴绘图(Python) [英] Plotting with time axis (Python)

问题描述

我又遇到了一个问题，那已经使我头痛了几个小时……而且我很确定这只是小事.

我得到了一个长数据文件，并创建了一个包含标题名称及其类型的列表:

col_headers = [('TIMESTAMP','|S21'),('XXX_1','<i8'),('YYY_2','<i8')

之后，我创建了一个包含选项的字典变量，最后使用

将其导入

bladata = scipy.genfromtxt(datafile, **kwargs)

为了提取我使用的时间信息

import datetime as dt
for i in range (0,len(bladata['TIMESTAMP']),1):
    datestring = bladata['TIMESTAMP'][i]
    #create a datetime object holding dates and times
    d = dt.datetime.strptime(datestring, '"%Y-%m-%d %H:%M:%S"')

最后我通过使用

将数据分配给变量

XXX = bladata['XXX_1']
YYY = bladata['YYY_2']

(顺便说一句，当我的数据文件中的标头名称不是XXX_1而是XXX(1)时，我收到错误消息找不到名为XXX(1)的字段"-我也该如何解决此问题?)

现在进行绘图时，我收到错误消息

x and y must have same first dimension

使用以下代码时

pylab.plot(dt, XXX)
pylab.plot(dt, YYY)
pylab.xlim(d.datetime(2014, 01, 10), d.datetime(2014, 06, 10))

我搜索了该错误消息，并找到了一种建议将列表转换为numpy数组的解决方案...但是，在哪里和哪一个?我很确定这根本不是什么大问题，但是我几个小时都无法解决...所以我很高兴收到任何有用的答复.

dit:为澄清起见... XXX和YYY是2种不同的测量值，我想在1个图中将其对应的日期可视化.

解决方案

在pylab.plot(dt, XXX)中，您尝试将导入的datetime模块本身与值列表相对应，这不是您想要的.

相反，您想要类似pylab.plot(times, XXX)的内容，其中times应该是包含与列表XXX相对应的datetime对象的列表.

您收到的错误消息指出传递给plot函数的2个参数应该是长度相同的列表.

请参见使用Matplotlib在Python中绘制时间，以获取更多信息，包括格式化x轴标签.

I ran into a problem again thats causing me headache for several hours already...and I'm pretty sure it's just a minor thing.

I got a long datafile and created a list with the header names and their types:

col_headers = [('TIMESTAMP','|S21'),('XXX_1','<i8'),('YYY_2','<i8')

After that I created a dictionary variable that holds the options and finally imported it with

bladata = scipy.genfromtxt(datafile, **kwargs)

For extracting time information I used

import datetime as dt
for i in range (0,len(bladata['TIMESTAMP']),1):
    datestring = bladata['TIMESTAMP'][i]
    #create a datetime object holding dates and times
    d = dt.datetime.strptime(datestring, '"%Y-%m-%d %H:%M:%S"')

And finally I assigned the data to a variable by using

XXX = bladata['XXX_1']
YYY = bladata['YYY_2']

(btw when the header name in my datafile is not XXX_1 but XXX(1) instead, I receive the error message "field named XXX(1) not found" - how can I solve this problem as well?)

Now when it comes to plotting, I receive the error message

x and y must have same first dimension

when using the following code

pylab.plot(dt, XXX)
pylab.plot(dt, YYY)
pylab.xlim(d.datetime(2014, 01, 10), d.datetime(2014, 06, 10))

I googled that error message and found a solution that suggested converting a list into a numpy array...but where and which one? I'm pretty sure that isn't a big problem at all, but I couldn't figure it out for several hours...so I'm happy for any usefull reply.

€dit: for clarification...XXX and YYY are 2 different measurements that I want to visualize in 1 plot versus its corresponding date.

解决方案

In pylab.plot(dt, XXX) you're trying to plot the imported datetime module itself against a list of values, which is not what you want.

Instead you want something like pylab.plot(times, XXX) where times should be a list containing the datetime objects corresponding to the list XXX.

The error message you are getting is pointing out the 2 arguments you pass to the plot function should be lists of the same length.

See Plotting time in Python with Matplotlib for further information including formatting the x-axis labels.

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