I wish to change a string like function.
let my function string is like 'x**2+2*x+1'.but I want to change x by r.
And I don't want to use x as a str during this replacement.
To do this I make a method whose parameter are formula and vav i.e., variable
So, I tried This:
def ModifyFormula(formula,vav):
vav=str(vav)
san_vav='r'
formula=formula.replace(vav,san_vav)
return formula
ModifyFormula('x**2+2*x+1',x)
But I got NameError: name 'x' is not defined, It is pretty obvious that is a error due to a undefined in last line of the code .
How I can approach the goal to 'r**2+2*r+1' without using x as str ?
It's not possible.
The last line will always be decoded.
Can you run a for loop over the names of multiple subsets?
For instance, I now have subsets dfVC1 up until dfVC20 and I would like to do something like:
for x in range(20):
print(dfVC[x])
I get this doesn't work... but wonder if there is a way to do this.
I'm going to assume your 'subsets' in this case are variables, named dbVC0, dbVC1, etc. Then, your problem is that you want to print all of them by number, but since they're variables, you can't.
One way to solve this would be to change how the 'subsets' are declared. Instead of
dfVC0 = ...
dfVC1 = ...
you could make one dfVC variable that's a dict, that holds all the others at their proper indices.
dfVC = {}
dfVC[0] = ...
dfVC[1] = ...
which would then allow you to access the various dbVC subsets in the way you're currently trying to.
But changing such a large part of the program isn't always possible. What you might be able to do instead is to figure out which object the dfVCs are attached to, and grab them by string.
If they're in the local namespace (i.e. were declared in the same function as you're currently executing in), you can call the built-in locals() to get a dict that you can then try to find your key in:
for x in range(20):
sname = f'dfVC{x}'
print(locals()[sname])
globals() can be used similarly, if your 'subsets' are in the global scope (i.e. declared outside of the current function).
And if your dfVC variables are attached to a class or module (or something else that behaves like a namespace), you can retrieve them using the built-in getattr() function:
for x in range(20):
sname = f'dfVC{x}'
print(getattr(self, sname)) # replace self with whichever object has the dbVC attached to it
I want to print to a file using print I import from __future___. I have the following as an import:
from __future__ import print_function
From now on, I can print using:
print("stuff", file=my_handle)
However, I have many calls to print in a function, so I would want to be able to use a function where the keyword argument is bound to my_handle. So, I use partial application:
printfile = partial(print, file=my_handle)
printfile("stuff")
printfile("more stuff")
which is what I intended. However, is there any way I can change to definition of print itself by partially applying the keyword argument? What I have tried was:
print = partial(print, file=my_handle)
however I got an error saying:
UnboundLocalError: local variable 'print' referenced before assignment
Is there any way to use print without mentioning my file every time?
print = partial(print, file=my_handle)
This line causes the UnboundLocalError on the second print, the one used as argument to partial(). This is because the name print is found to be a local variable in this particular function --- because you assign to it, in this case in the same line, more generally in the same function. You can't use the same variable name in one function to refer sometimes to a global and sometimes to a local.
To fix it you need to use a different name:
fprint = partial(print, file=my_handle).
I have some code like:
def example(parameter):
global str
str = str(parameter)
print(str)
example(1)
example(2)
The first call to example works, but then the second time around I get an error like:
Traceback (most recent call last):
File "test.py", line 7, in <module>
example(2)
File "test.py", line 3, in example
str = str(parameter)
TypeError: 'str' object is not callable
Why does this happen, and how can I fix it?
If you are in an interactive session and encountered a problem like this, and you want to fix the problem without restarting the interpreter, see How to restore a builtin that I overwrote by accident?.
Where the code says:
global str
str = str(parameter)
You are redefining what str() means. str is the built-in Python name of the string type, and you don't want to change it.
Use a different name for the local variable, and remove the global statement.
Note that if you used code like this at the Python REPL, then the assignment to the global str will persist until you do something about it. You can restart the interpreter, or del str. The latter works because str is not actually a defined global variable by default - instead, it's normally found in a fallback (the builtins standard library module, which is specially imported at startup and given the global name __builtins__).
While not in your code, another hard-to-spot error is when the % character is missing in an attempt of string formatting:
"foo %s bar %s coffee"("blah","asdf")
but it should be:
"foo %s bar %s coffee"%("blah","asdf")
The missing % would result in the same TypeError: 'str' object is not callable.
In my case I had a class that had a method and a string property of the same name, I was trying to call the method but was getting the string property.
Note that TypeError: 'str' object is not callable means only that there is an attempt to call (i.e., use function-call syntax) a string (i.e., any name that previously had a string assigned to it). Using any other built-in method as variable name can cause the exact same error message.
You can get this error if you have variable str and trying to call str() function.
Whenever that happens, just issue the following ( it was also posted above)
>>> del str
That should fix it.
Another case of this: Messing with the __repr__ function of an object where a format() call fails non-transparently.
In our case, we used a #property decorator on the __repr__ and passed that object to a format(). The #property decorator causes the __repr__ object to be turned into a string, which then results in the str object is not callable error.
Check your input parameters, and make sure you don't have one named type. If so then you will have a clash and get this error.
str = 'Hello World String'
print(str(10)+' Good day!!')
Even I faced this issue with the above code as we are shadowing str() function.
Solution is:
string1 = 'Hello World String'
print(str(10)+' Good day!!')
I had the same error. In my case wasn't because of a variable named str. But because I named a function with a str parameter and the variable the same.
same_name = same_name(var_name: str)
I run it in a loop. The first time it run ok. The second time I got this error. Renaming the variable to a name different from the function name fixed this. So I think it's because Python once associate a function name in a scope, the second time tries to associate the left part (same_name =) as a call to the function and detects that the str parameter is not present, so it's missing, then it throws that error.
This error can also occur as a result of trying to call a property (as though it were a function):
class Example:
#property
def value():
return 'test'
e = Example()
print(e.value()) # should just be `e.value` to get the string
This problem can be caused by code like:
"Foo" ("Bar" if bar else "Baz")
You can concatenate string literals by putting them next to each other, like "Foo" "Bar". However, because of the open parenthesis, the code was interpreted as an attempt to call the string "Foo" as if it were a function.
it could be also you are trying to index in the wrong way:
a = 'apple'
a(3) ===> 'str' object is not callable
a[3] = l
it is recommended not to use str int list etc.. as variable names, even though python will allow it.
this is because it might create such accidents when trying to access reserved keywords that are named the same
This error could also occur with code like:
class Shape:
def __init__(self, colour):
self.colour = colour
def colour(self):
print("colour:", self.colour)
myShape = Shape("pink")
myShape.colour()
In the __init__ method, we assign an attribute colour, which has the same name as the method colour. When we later attempt to call the method, the instance's attribute is looked up instead. myShape.colour is the string "pink", which is not callable.
To fix this, change either the method name or the variable name.
I also got this error.
For me it was just a typo:
I wrote:
driver.find_element_by_id("swal2-content").text()
while it should have been:
driver.find_element_by_id("swal2-content").text
In my case, I had a Class with a method in it. The method did not have 'self' as the first parameter and the error was being thrown when I made a call to the method. Once I added 'self,' to the method's parameter list, it was fine.
FWIW I just hit this on a slightly different use case. I scoured and scoured my code looking for where I might've used a 'str' variable, but could not find it. I started to suspect that maybe one of the modules I imported was the culprit... but alas, it was a missing '%' character in a formatted print statement.
Here's an example:
x=5
y=6
print("x as a string is: %s. y as a string is: %s" (str(x) , str(y)) )
This will result in the output:
TypeError: 'str' object is not callable
The correction is:
x=5
y=6
print("x as a string is: %s. y as a string is: %s" % (str(x) , str(y)) )
Resulting in our expected output:
x as a string is: 5. y as a string is: 6
It also give same error if math library not imported,
import math
I realize this is not a runtime warning, but PyCharm gave me this similarly-worded IDE warning:
if hasattr(w, 'to_json'):
return w.to_json()
# warning, 'str' object is not callable
This was because the IDE assumed w.to_json was a string. The solution was to add a callable() check:
if hasattr(w, 'to_json') and callable(w.to_json):
return w.to_json()
Then the warning went away. This same check may also prevent the runtime exception in the original question.
I'm trying to dynamically create buttons at runtime with PyQT4.7
However, this being my first python program I'm not sure how to get the functionality I want.
I would like to be able to substitute a text string for an attribute name:
i.e.
for each in xrange(4):
myname = "tab1_button%s" % each #tab1_button0, tab1_button1, tab1_button2
#self.ui.tab1_button0 = QtGui.QPushButton(self.ui.tab) <--normal code to create a named button
setattr(self.ui,myname,QtGui.QPushButton(self.ui.tab)) #rewrite of line above to dynamicly generate a button
#here's where I get stuck. this code isn't valid, but it shows what i want to do
self.ui.gridLayout.addWidget(self.ui.%s) % myname
#I need to have %s be tab1_button1, tab1_button2, etc. I know the % is for string substituion but how can I substitute the dynamically generated attribute name into that statement?
I assume there's a basica language construct I'm missing that allows this. Since it's my first program, please take it easy on me ;)
If I interpreted this correctly, I think what you want is this:
self.ui.gridLayout.addWidget(getattr(self.ui,myname))
Give that a go. In Python the following two statements are functionally equivalent (from the link below):
value = obj.attribute
value = getattr(obj, "attribute-name")
For extra context:
http://effbot.org/zone/python-getattr.htm
Just assign the button to a variable so you can both set the attribute and add the widget.
for i in range(4):
name = 'button%d' % i
button = QtGui.QPushButton(...)
setattr(self, name, button)
self.ui.gridLayout.addWidget(button)
Personally I would add the buttons to a list instead of giving them different names.
I think you might benefit from knowledge of lists (commonly called arrays in other languages)
self.buttons = [None, None, None, None]
for each in xrange(4):
self.buttons[each] = QtGui.QPushButton(self.ui.tab)
self.ui.gridLayout.addWidget(self.buttons[each])
For a tutorial on Python lists:
http://effbot.org/zone/python-list.htm