我从 matplotlib 中看到了一些奇怪的结果,我几乎使用了股票示例将其添加到 Django;
def graph(request):
if request.user.is_authenticated():
user = request.user.first_name
else:
return redirect('/login')
form = GetGraphData(request.POST or None)
if form.is_valid():
os.environ['MPLCONFIGDIR'] = "/tmp"
from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
from matplotlib.figure import Figure
from matplotlib.dates import DateFormatter
from_date = form.cleaned_data['chosen_from_date']
to_date = form.cleaned_data['chosen_to_date']
graph_property = form.cleaned_data['chosen_property']
rack = form.cleaned_data['chosen_rack']
query = "select %s,reading_date from readings where reading_date" \
" between '%s' and '%s' and pdu_location like '%s%%'" \
%(graph_property,from_date, to_date, rack)
results = db.db_query(query)
if results[0]:
fig=Figure()
fig.clear()
ax=fig.add_subplot(111)
x=[]
for i in results[0]:
x.append(i[1])
y=[]
for i in results[0]:
y.append(i[0])
ax.plot_date(x, y, '-')
ax.xaxis.set_major_formatter(DateFormatter('%Y-%m-%d'))
ax.set_title(rack)
ax.set_xlabel("Date")
ax.set_ylabel(graph_property)
fig.autofmt_xdate()
canvas=FigureCanvas(fig)
response=HttpResponse(content_type='image/png')
canvas.print_png(response)
return response
else:
error_message = 'There were no results for that query, check' \
' your dates and try again.'
return render_to_response('generic_message.html'
,{'message':error_message,'title':'No results'})
template_dict = {'username':user, 'form':form,'view':True}
return render_to_response('get_circuit.html',template_dict)
缩进是正确的,它只是奇怪地粘贴在上面,在 x 轴上,我们最终得到一个日期时间对象列表,在 y 轴上,我们最终得到一个浮点数列表。
我得到下面的图表;
您可以看到图表的左侧看起来很奇怪。作为此查询的一部分,有 96 个数据点返回,我还注意到,当 y 轴上有超过 1000 个数据点时,它变得更加疯狂。
有人有什么建议来解决这个问题吗?