I use pySerial to read data from serial port and I am trying to convert the string below to integer:
s=ser.read()
int(s)
but i can't.The error i take is:
Traceback (most recent call last):
File "C:\Documents and Settings\User\Desktop\ser1.py", line 24, in <module>
int(s)
ValueError: invalid literal for int() with base 10: ''
Do anyone know how to convert it? Thanks in advance!
int('0'+s)
Prepend the string with a zero. Think of it as a miniature parsing step. I can't think of a case when this wouldn't work.
This is the use-case I had: Convert a numpy array of strings to integers.
def _intStrArray(pos): return int('0'+pos)
np.intStrArray = np.vectorize(_intStrArray)
print(arr)
array([['', '', '', '', '', '', '', '', '', '', '', '', ''],
['', '', '1', '', '', '2', '', '2', '', '', '', '', ''],
['', '2', '2', '', '3', '2', '', '', '2', '', '', '', ''],
['', '2', '', '3', '2', '2', '3', '4', '', '4', '', '', ''],
['', '', '3', '2', '2', '', '', '3', '3', '', '2', '1', ''],
['', '', '', '1', '2', '', '3', '2', '', '', '', '', ''],
['', '', '2', '', '2', '4', '3', '', '2', '1', '', '2', ''],
['', '', '', '', '', '', '2', '', '', '1', '', '1', ''],
['', '', '', '', '', '', '', '', '', '', '', '', '']], dtype=object)
print(np.intStrArray(arr))
array([[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 1, 0, 0, 2, 0, 2, 0, 0, 0, 0, 0],
[0, 2, 2, 0, 3, 2, 0, 0, 2, 0, 0, 0, 0],
[0, 2, 0, 3, 2, 2, 3, 4, 0, 4, 0, 0, 0],
[0, 0, 3, 2, 2, 0, 0, 3, 3, 0, 2, 1, 0],
[0, 0, 0, 1, 2, 0, 3, 2, 0, 0, 0, 0, 0],
[0, 0, 2, 0, 2, 4, 3, 0, 2, 1, 0, 2, 0],
[0, 0, 0, 0, 0, 0, 2, 0, 0, 1, 0, 1, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]])
After discovering just how messy my data was, I also added a str(). This is optional if the datatype is reliable.
def _intStrArray(pos): return int('0'+str(pos))
np.intStrArray = np.vectorize(_intStrArray)
None instead of 0.
You could catch the exception and default the value to something, but I really don't see there's anything meaningful from something that doesn't exist...
s = ser.read()
try:
ival = int(s)
except ValueError as e:
ival = 0 # ????
It would be more likely that the data you're expecting just hasn't been received yet and you should be waiting on the serial port until sufficient data is received before doing anything with it...
int(x=0) int(x, base=10)
Convert a number or string x to an integer, or return 0 if no arguments are given. If x is a number, it can be a plain integer, a long integer, or a floating point number. If x is floating point, the conversion truncates towards zero. If the argument is outside the integer range, the function returns a long object instead.
If x is not a number or if base is given, then x must be a string or Unicode object representing an integer literal in radix base. Optionally, the literal can be preceded by + or - (with no space in between) and surrounded by whitespace. A base-n literal consists of the digits 0 to n-1, with a to z (or A to Z) having values 10 to 35. The default base is 10. The allowed values are 0 and 2-36. Base-2, -8, and -16 literals can be optionally prefixed with 0b/0B, 0o/0O/0, or 0x/0X, as with integer literals in code. Base 0 means to interpret the string exactly as an integer literal, so that the actual base is 2, 8, 10, or 16.
