Untitled

TypeError: float() argument must be a string or a number

from flask import Flask, request, render_template
from datetime import datetime
from ubidots import ApiClient
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
import matplotlib.animation as animation
from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
from matplotlib.figure import Figure
import io

app = Flask(__name__)

//get the latest value of the ldr sensor from Ubidots
def get_records():
    api = ApiClient(token='XXXXXXXXXXXXXXXXXXXXXXX')
    my_variable = api.get_variable('XXXXXXXXXXXXXXXXXXXX')
    ldr = my_variable.get_values(1)
    return ldr

//get the latest timestamp from Ubidots
def get_times():
    api = ApiClient(token='XXXXXXXXXXXXXXXXXXXXXXXX')
    variable = api.get_variable('XXXXXXXXXXXXXXXXXXXXXX')
    value = variable.get_values(1)[0]
    timestamp = value.get('timestamp')
    global t
    t= mdates.epoch2num(timestamp)
    return t

//render the graph with x and y values of time and sensor values respectively and send to Flask
@app.route('/', methods=['POST'])
def my_form_post():
    ldr= get_records()
    time= get_time()
    templateData = {
        'ldr'   : ldr,
        'time'  : t
        }
    return render_template('main.html', **templateData)

//Plotting the graph using Matplotlib
@app.route('/')
def plot_temp():
    ldr= get_records()
    ys = ldr
    fig = Figure()
    axis = fig.add_subplot(1,1,1)
    axis.set_title("Light Intensity")
    axis.set_xlabel("Time")
    axis.xaxis.set_major_formatter(mdates.DateFormatter('%H:%M:%S'))
    axis.grid(True)
    time= get_times()
    xs = time
    axis.plot(xs,ys)
    canvas = FigureCanvas(fig)
    output = io.BytesIO()
    canvas.print_png(output)
    response = make_response(output.getvalue())
    response.mimetype = 'image/png'
    ani= animation.FuncAnimation(fig, animate, interval=3000)
    return response

if __name__ == "__main__":
   app.run(host='0.0.0.0', port=80, debug=True)

<!DOCTYPE html>
   <head>
      <title>{{ title }}</title>
   </head>

   <body>
      <h1>Hello, World!</h1>
      <h2>The date and time on the server is: {{ time }}</h2>
      <img src="/" alt="Image Placeholder" width="49%">
   </body>
</html>