How do I generate a graph from Arduino sensor data? I used a DHT 11 sensor with an Arduino Uno to measure temperature and humidity. I used the following code to print the temperature and relative humidity in Serial Monitor.
dht DHT;

#define DHT11_PIN 7

void setup(){
  Serial.begin(9600);
}

void loop()
{
  int chk = DHT.read11(DHT11_PIN);
  delay(1000);
  Serial.print(DHT.temperature);
  Serial.print(&quot; , &quot;);
  Serial.println(DHT.humidity);
  delay(1000);
}

The Serial monitor printed the following data values in a list in the order of: time, temperature (Celsius), humidity (percentage).
22:17:55.686 -&gt; 25.00 , 55.00
22:17:57.713 -&gt; 25.00 , 55.00
22:17:59.741 -&gt; 25.00 , 54.00
22:18:01.769 -&gt; 25.00 , 54.00
22:18:03.793 -&gt; 25.00 , 55.00
22:18:05.813 -&gt; 25.00 , 54.00
22:18:07.837 -&gt; 25.00 , 54.00
22:18:09.868 -&gt; 25.00 , 55.00
22:18:11.880 -&gt; 25.00 , 55.00
22:18:13.900 -&gt; 25.00 , 55.00
22:18:15.915 -&gt; 25.00 , 56.00
22:18:17.950 -&gt; 25.00 , 56.00
22:18:19.972 -&gt; 25.00 , 56.00
22:18:21.994 -&gt; 25.00 , 56.00
22:18:24.024 -&gt; 25.00 , 56.00
22:18:26.043 -&gt; 25.00 , 56.00
22:18:28.093 -&gt; 25.00 , 55.00
22:18:30.122 -&gt; 25.00 , 55.00
22:18:32.141 -&gt; 25.00 , 55.00
22:18:34.142 -&gt; 25.00 , 55.00

I used the PuTTY software to save the sensor data to a CSV file. However, I end up with a few strange numbers at the top before the values start printing properly.
25.25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00
25.00 , 53.00

Also, when I open the CSV file in Excel, the time values have disappeared, even though they were there in the serial monitor.

What can I do to get the time stamps to show up in my spreadsheet? Additionally, is there a way I can have the graph automatically update as more data is read?
Perhaps the built-in Arduino Serial Plotter is all you need to visualize your data.  I wrote a tutorial a while back that might help you.