从python中的列表中删除datetime.datetime

Question

I'm attempting to get 2 different elements from an XML file, I'm trying to print them as the x and y on a scatter plot, I can manage to get both the elements but when I plot them it only uses one of the dates to plot the other elements. I'm using the below code to get a weather HTML and save it as an XML.

        url = "http://api.met.no/weatherapi/locationforecast/1.9/?lat=52.41616;lon=-4.064598"
        response = requests.get(url)
        xml_text=response.text
        weather= bs4.BeautifulSoup(xml_text, "xml")
        f = open('file.xml', "w")
        f.write(weather.prettify())
        f.close()

I'm then trying to get the time ('from') element and the ('windSpeed' > 'mps') element and attribute. I'm then trying to plot it as an x and y on a scatter plot.

 with open ('file.xml') as file:
     soup = bs4.BeautifulSoup(file, "xml")
     times = soup.find_all("time")
     windspeed = soup.select("windSpeed")
     form = ("%Y-%m-%dT%H:%M:%SZ")
     x = []
     y = []
     for element in times:
         time = element.get("from")
         t = datetime.datetime.strptime(time, form)
         x.append(t)
     for mps in windspeed:
         speed = mps.get("mps")
         y.append(speed)
     plt.scatter(x, y)         
     plt.show() 

I'm trying to make 2 lists from 2 loops, and then read them as the x and y, but when I run it it gives the error; raise ValueError("x and y must be the same size") ValueError: x and y must be the same size

I'm assuming it's because it prints the list as datetime.datetime(2016, 12, 22, 21, 0), how do I remove the datetime.datetime from the list.

I know there's probably a simple way of fixing it, any ideas would be great, you people here on stack are helping me a lot with learning to code. Thanks

Answer 1

Simply make two lists one containing x-axis values and other with y-axis values and pass to scatter function

plt.scatter(list1, list2);

Answer 2

I suggest that you use lxml for analysing xml because it gives you the ability to use xpath expressions which can make life much easier. In this case, not every time entry contains a windSpeed entry; therefore, it's essential to identify the windSpeed entries first then to get the associated times. This code does that. There are two little problems I usually encounter: (1) I still need to 'play' with xpath to get it right; (2) Sometimes I get a list when I expect a singleton which is why there's a '[0]' in the code. I find it's better to build the code interactively.

>>> from lxml import etree
>>> XML = open('file.xml')
>>> tree = etree.parse(XML)
>>> for count, windSpeeds in enumerate(tree.xpath('//windSpeed')):
...     windSpeeds.attrib['mps'], windSpeeds.xpath('../..')[0].attrib['from']
...     if count>5:
...         break
...     
('3.9', '2016-12-29T18:00:00Z')
('4.8', '2016-12-29T21:00:00Z')
('5.0', '2016-12-30T00:00:00Z')
('4.5', '2016-12-30T03:00:00Z')
('4.1', '2016-12-30T06:00:00Z')
('3.8', '2016-12-30T09:00:00Z')
('4.4', '2016-12-30T12:00:00Z')