Still have NaN result

Programming Questions

samer1607

in Programming Questions • 1 month ago

Hi, i have a stream of data receiving from serial port (Arduino), and want to convert this stream of data to flaot numbers, but i faced NaN problem and tried to solve it in several ways but no update, i hope you can help me to know where's my misstake and how to solve it. below is my code and then the result.

Thanks alot

import processing.serial.*;
import java.text.*;
import java.util.*;
PrintWriter output;
DateFormat fnameFormat= new SimpleDateFormat("yyyyMMdd");
String fileName;
Serial myPort;
short portIndex = 0;
float floatvalue;
String stringvalue;
void setup()
{
size(200, 200);
// Open whatever serial port is connected to Arduino.
String portName = Serial.list()[portIndex];
println(Serial.list());
println(" Connecting to -> " + Serial.list()[portIndex]);
println(portName);
myPort = new Serial(this, portName, 9600);
Date now = new Date();
fileName = fnameFormat.format(now);
println(fileName);
output = createWriter(fileName+".txt"); // save the file in the sketch folder
}
void draw()
{
while(myPort.available()>0)
{
stringvalue=myPort.readString();
floatvalue=float(stringvalue);
if(floatvalue!=Float.NaN)
{
output.println(floatvalue);
}
}
}
void keyPressed() {
output.flush();
output.close();
exit();
}

and the result

1.0

2.0

3.0

NaN

4.0

NaN

5.0

NaN

6.0

NaN

7.0

8.0

9.0

10.0

NaN

1.0

2.0

13.0

14.0

NaN

15.0

NaN

16.0

NaN

17.0

NaN

1.0

8.0

Replies(8)

samer1607

Re: Still have NaN result

1 month ago

I solved the problem by using another trick if ( ! Float.isNaN (floatvalue) ) command instead of if(floatvalue!=Float.NaN) , but now I'm facing new issue which is some of the result are convert it in wrong way, please check the blow result and you will find i Bold and shadowed some numbers to show you the wring numbers

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

1.0

12.0

13.0

14.0

15.0

16.0

1.0

7.0

18.0

19.0

20.0

2.0

1.0

22.0

2.0

3.0

24.0

25.0

PhiLho

Re: Still have NaN result

1 month ago

" some of the result are convert it in wrong way"
Well, what is the expected result for these numbers?

samer1607

Re: Still have NaN result

1 month ago

they should be (11.0,21.0,23.0)

Note:- it's a counter generator from 1 to 25 .

Thanks

kooogy

Re: Still have NaN result

1 month ago

have you tried printing the string out before converting it to a float? i'm guessing there's something wrong with it.

samer1607

Re: Still have NaN result

1 month ago

Yes off course i tried that and the result printed normally , and that is confusing me .

PhiLho

Re: Still have NaN result

1 month ago

I read the readString() documentation, and I see: " Returns all the data from the buffer as a String."
So Serial reads data and fills a buffer, until you read this buffer. If you read too often, you can read partially received data.
You better use readStringUntil() with a separator defined on the sending side.

What you see are the digits of the next number, cut in two parts because you read the first digit before the second one is received.

quarks

Re: Still have NaN result

1 month ago

FYI

The test
floatvalue!=Float.NaN
will always return true because the Java language does not consider two NaN(s) to be the equal. So even is floatValue is NaN it will not be the same as Float.NaN so the test returns true.

For instance if we have a float variable called x then

if(x != x){
// Can Only get here if x is NaN !

}

As you have discovered the only safe way is to use the method
Float.isNaN(float_variable)

samer1607

Re: Still have NaN result

1 month ago

Hi, I found what was the problem, i have 1 second delay in the Arduino side and not in the Processing side and that's make the String keep reading the serial contentiously without waiting the sender to send the data.