If I want to see the str.replace() function: help(str.replace)
the result is:
Help on method_descriptor:
replace(...)
S.replace(old, new[, count]) -> str
Return a copy of S with all occurrences of substring
old replaced by new. If the optional argument count is
given, only the first count occurrences are replaced.
(END)
but how use help file.read or readlines?
for example, help(file.read) and help(read) are both errors:
>>> help(file)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'file' is not defined
>>> help(file.read)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'file' is not defined
>>> help(read)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'read' is not defined
How can I use help see file functions?
The file type has been removed from Python 3. Look at the io module instead:
>>> import io
>>> help(io.TextIOBase.read)
Help on method_descriptor:
read(...)
Read at most n characters from stream.
Read from underlying buffer until we have n characters or we hit EOF.
If n is negative or omitted, read until EOF.
Related
In python exceptions, does the TypeError check occur before doing the ValueError check? For example:
>>> chr(123)
'{'
>>> chr('x')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: an integer is required (got type str)
>>> chr(18293939)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: chr() arg not in range(0x110000)
>>> chr(1829393993939393)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
OverflowError: signed integer is greater than maximum
Or what is the order in which the various errors are checked? Is there documentation on the order of operations/evaluations for the difference Exception types?
None of this is documented (i.e., guaranteed). That said, it would be impossible to raise a sensible ValueError if there was no value of the correct type to compare. The difference between ValueError and OverflowError is surely an implementation detail entirely, since anything that overflows the target type would of course be out of any restricted range for that type.
I am trying to open and load pickle file but by two ways. But every time I am getting an error.
Request you to please help.
First way :
enron_data = pickle.load(open("D:/New/ud120-projects/final_project/final_project_dataset.pkl", "r"))
Error: Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: a bytes-like object is required, not 'str'
Second Way :
enron_data = pickle.load(open("D:/New/ud120-projects/final_project/final_project_dataset.pkl", "rb"))
Error : Traceback (most recent call last):
File "<stdin>", line 1, in <module>
_pickle.UnpicklingError: the STRING opcode argument must be quoted
Request you to please help
If you are on Windows you have to use a raw string and backslashes like this:
r'D:\path\to\your\file'
Why these below statements are giving error
>>> exec("x={}".format('b'))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<string>", line 1, in <module>
NameError: name 'b' is not defined
I need the result to be
x='b'
You should provide another pair of quotes
>>> exec("x={}".format("'b'"))
>>> x
'b'
Why?
When you write
exec("x={}".format('b'))
you are trying to write
x=b
obviously python doesn't know what b is unless you have defined it before.
Where as when you write
exec("x={}".format("'b'"))
It is same as
x='b'
I am trying to generate the help text at runtime and i am not able to use the pydoc command in Windows. When i type
>>> pydoc(atexit)
Traceback (most recent call last):
File "<console>", line 1, in <module>
NameError: name 'pydoc' is not defined
I have already set up the environment variables for pydoc.py file. C:\Python33\Lib\pydoc.py.
This also not works like it works for >>help('atexit')
>>> pydoc('atexit')
Traceback (most recent call last):
File "<console>", line 1, in <module>
NameError: name 'pydoc' is not defined
Whats the possible reason for it.
Updates:
>>> import pydoc
>>> pydoc(sys)
Traceback (most recent call last):
File "<console>", line 1, in <module>
TypeError: 'module' object is not callable
>>> pydoc('sys')
Traceback (most recent call last):
File "<console>", line 1, in <module>
TypeError: 'module' object is not callable
Like any library in Python, you need to import it before you can use it.
Edit What exactly are you trying to achieve? Modules are indeed not callable. pydoc.help is the function you want, although I don't really know why you need it, since as you note the standalone help function does the same thing already.
I'm trying to use PyKDE, PyKDE.kdecore.KStandardDirs to be precise. This method is called with two strings according to the documentation and according to the PyQt4 documentation, I can use standard Python strs instead of QString.
This doesn't work:
>> KStandardDirs.locate()("socket", "foo")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: KStandardDirs.locate(): not enough arguments
>>> KStandardDirs.locate("socket", "foo")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: KStandardDirs.locate(): argument 1 has unexpected type 'str'
I can't use QString either because it doesn't seem to exist:
>>> from PyQt4.QtCore import QString
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: cannot import name QString
>>> from PyQt4.QtCore import *
>>> QString
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'QString' is not defined
What am I doing wrong?
I suspect that PyKDE is not yet Python 3 ready, at least as far as that error message is concerned; try passing in a bytestring instead:
KStandardDirs.locate(b"socket", "foo")