I need to convert a list into a string and then do the reverse process. Note that one script will convert List->String and another script will convert String->List, so store the list in a variable is not a solution. Use split(', ') or similar is not a solution either in all cases. So, as a challange I invite you to do the conversion in the following example:
l = ['ab,.cd\'ac"', b'\x80', '\r\nHi, !', b'\x01']
str_l = str(l)
I have tried one thing that worked: using exec() built-in function but people says is not a good practice, so I invite you to give me another alternative. Also I am having problems using exec() inside a function but that's another question that you can check -> Using exec() inside a function Python 3
This should work:
str_l = ("|").join(l)
Which gives you your first string. Then do:
l_2 = str_l.split("|")
Which gives you your second list.
Related
Short version:
How do you store functions in a list and only have them be executed when they are called using their index position in the list?
Long Version:
So I am writing a program that rolls a user-chosen number of six-sided dice, stores the results in a list and then organizes the results/ data in a dictionary.
After the data is gathered the program gives the user options from 0-2 to choose from and asks the user to type a number corresponding to the option they want.
After this input by the user, a variable, lets say TT, is assigned to it. I want the program to use TT to identify which function to run that is contained within a list called "Executable_options" by using TT as the index posistion of this function within the list.
The problem I am having is that I have to have the list that contains the functions on a line after the functions have been defined and when I initialize the list it goes through and executes all functions within it in order when I don't want it to. I just want them to be in the list for calling at a later date.
I tried to initialise the list without any functions in and then append the functions individually, but every time a function is appened to the list it is also executed.
def results():
def Rolling_thunder():
def roll_again():
The functions contains things, but is unnecessary to show for the question at hand
Executable_options = []
Executable_options.append(results())
Executable_options.append(Rolling_thunder())
Executable_options.append(roll_again)
options = len(Executable_options)
I am relatively new to Python so I am still getting my head around it. I have tried searching for the answer to this on existing posts, but couldn't find anything so I assume I am just using the wrong key words in my search.
Thank you very much for taking the time to read this and for the answers provided.
Edit: Code now works
The () on the end of the function name calls it - i.e. results() is the call to the results method.
Simply append to the list without the call - i.e:
Executable_options.append(results)
You can then call it by doing e.g.:
Executable_options[0]()
as per your given data the code will look like this:
def results():
def Rolling_thunder():
def roll_again():
Executable_options = []
Executable_options.append(results)
Executable_options.append(Rolling_thunder)
Executable_options.append(roll_again)
for i in range(0,len(Executable_options)):
Executable_options[i]()
this will work for you.
I´m currently writing a test script for a custom python console. My question is, how do I let the user input a already defined function?
Example: My script gets an input from the user. It detects, that its a line of code, therefore executes it.
Does anyone know how I can implement this as code?
Thanks in advance!
If the functions are already defined I would suggest you define a dictionary of choices to pick from.
It's typically a very bad idea to let a user input and execute arbitrary code.
U can use the eval() function which is builtin. it takes the string parameter and executes the parsed string. For example:
x = 1
print(eval('x + 1'))
>>>2
Trying to understand how "%s%s" %(a,a) is working in below code I have only seen it inside print function thus far.Could anyone please explain how it is working inside int()?
a=input()
b=int("%s%s" %(a,a))
this "%s" format has been borrowed from C printf format, but is much more interesting because it doesn't belong to print statement. Note that it involves just one argument passed to print (or to any function BTW):
print("%s%s" % (a,a))
and not (like C) a variable number of arguments passed to some functions that accept & understand them:
printf("%s%s,a,a);
It's a standalone way of creating a string from a string template & its arguments (which for instance solves the tedious issue of: "I want a logger with formatting capabilities" which can be achieved with great effort in C or C++, using variable arguments + vsprintf or C++11 variadic recursive templates).
Note that this format style is now considered legacy. Now you'd better use format, where the placeholders are wrapped in {}.
One of the direct advantages here is that since the argument is repeated you just have to do:
int("{0}{0}".format(a))
(it references twice the sole argument in position 0)
Both legacy and format syntaxes are detailed with examples on https://pyformat.info/
or since python 3.6 you can use fstrings:
>>> a = 12
>>> int(f"{a}{a}")
1212
% is in a way just syntactic sugar for a function that accepts a string and a *args (a format and the parameters for formatting) and returns a string which is the format string with the embedded parameters. So, you can use it any place that a string is acceptable.
BTW, % is a bit obsolete, and "{}{}".format(a,a) is the more 'modern' approach here, and is more obviously a string method that returns another string.
this is my first time asking a question so let me know if I am doing something wrong (post wise)
I am trying to create a function that writes into a .txt but i seem to get two very different results between calling it from within a module, and writing the same loop in the shell directly. The code is as follows:
def function(para1, para2): #para1 is a string that i am searching for within para2. para2 is a list of strings
with open("str" + para1 +".txt", 'a'. encoding = 'utf-8') as file:
#opens a file with certain naming convention
n = 0
for word in para2:
if word == para1:
file.write(para2[n-1]+'\n')
print(para2[n-1]) #intentionally included as part of debugging
n+=1
function("targetstr". targettext)
#target str is the phrase I am looking for, targettext is the tokenized text I am
#looking through. this is in the form of a list of strings, that is the output of
#another function, and has already been 'declared' as a variable
when I define this function in the shell, I get the correct words appearing. However, when i call this same function through a module(in the shell), nothing appears in the shell, and the text file shows a bunch of numbers (eg: 's93161), and no new lines.
I have even gone to the extent of including a print statement right after declaration of the function in the module, and commented everything but the print statement, and yet nothing appears in the shell when I call it. However, the numbers still appear in the text file.
I am guessing that there is a problem with how I have defined the parameters or how i cam inputting the parameters when I call the function.
As a reference, here is the desired output:
‘She
Ashley
there
Kitty
Coates
‘Let
let
that
PS: Sorry if this is not very clear as I have very limited knowledge on speaking python
I have found the solution to issue. Turns out that I need to close the shell and restart everything before the compiler recognizes the changes made to the function in the module. Thanks to those who took a look at the issue, and those who tried to help.
I am trying to implement code in parallel using Julia. I'm using the #everywhere macro in order to make all processes fetch data from a RemoteRef.
Is it possible to use a variable name thats only defined on the first process in the #everywhere expression and somehow specify that I want it to send the value of that variable, and not the variable name, to all processes?
Example:
r = RemoteRef()
put(r, data)
#everywhere data = fetch(r)
This returns an error because r is not defined on all processes.
How should I move data to all processes?
Also, can I tell Julia to put the value instead of the variable name in the expression?
Something akin to how name = "John"; println("Hello, $name") will print "Hello, John"
To find the functions (and macros) Spencer pointed in a nice little package, checkout ParallelDataTransfer.jl. The tests are good examples of usage (and the CI shows that these tests pass on v0.5 on all platforms).
For your problem, you can use the sendto function:
z = randn(10, 10); sendto(workers(), z=z)
#everywhere println(z)