I've written a program and want to call the functions in the main. However, I've been receiving a SyntaxError. I'm not sure what I'm doing wrong. Here is my code, I've tried a few things but the main function won't call the rest of the functions.
class Matrix(object):
def open_file():
'''Opens the file if it exists, otherwise prints out error message'''
Done = False
while not Done:
try:
File = input("Enter a filename: ").lower() #Asks user for a file to input
Open_File = open(File, "r") #Open the file if it exists and reads it
Info = Open_File.readlines()[1:]
Open_File.close() #Close the file
Done = True #Exits the while loop
except FileNotFoundError:
print("Sorry that file doesn't exist!") #prints out error message if file doesn't exist
return Info #Info is the file_pointer(fp)
def __init__(self): # This completed method is given
'''Create and initialize your class attributes.'''
self._matrix = {} #Intialize the matrix
self._rooms = 0 #Set the rooms equal to zero
def read_file(self, Info): #Info is equvalient to the file pointer or fp
'''Build an adjacency matrix that you read from a file fp.'''
self._rooms = Info.readline()
self._rooms = int(self._rooms)
for line in Info:
a, b = map(int, line.split())
self._matrix.setdefault(a, set()).add(b)
self._matrix.setdefault(b, set()).add(a)
return self._rooms and self._matrix
def __str__(self):
'''Return the adjacency matrix as a string.'''
s = str(self._matrix)
return s #__str__ always returns a string
def main(self):
matrix = Matrix()
info = matrix.open_file()
matrix.read_file(info)
s = str(matrix)
print(s)
if __name__ == '__main__':
m = Matrix()
m.main()
A few things:
it's self.read_file, not just read_file. It's an instance method so you need to use self.
Same for __init__(self), you need to call self.__init__. Although typically you don't do this manually. You would "instantiate" the class via Matrix().
You can't assign to a function call, so open_file() = Info simply doesn't make sense. Perhaps you mean info = open_file().
It looks like you're a little confused about how to lay out your class. Try leaving main outside of the class, like this (untested):
def main:
matrix = Matrix()
info = matrix.open_file()
matrix.read_file(info)
s = str(matrix)
print(s)
You will also need to dedent if __name__ == '__main__' to the global scope.
Ideally you may want to write something like below. Also, your open_file() has to be rewritten.
class Matrix(object):
def open_file(self):
File = input("Enter a filename: ").lower() #Asks user for a file to input
fp = open(File, "r")
return fp
#### Your matrix class code goes here
def main():
myMatrix = Matrix()
fp = myMatrix.open_file()
ret = myMatrix.read_file(fp)
print(myMatrix)
if __name__ == "__main__":
main()
There is an error in your program's entry. ' if name == 'main':'shouldn't be included in a Class. It should be global. And another, you want to call a member function of Matrix, but where is the object of Matrix. The code below is correct:
Class Matrix(object):
#################
your codes
#################
if __name__ == '__main__':
m = Matrix()
m.main()
the way this is posted
if __name__ == "__main__":
main()
is going to be executed when the class is defined -- not when the program is run. As written, the class won't have been instantiated so there's no Matrix object on which you can call main().
You'll need to move the call out one indent, so it is aligned with the class definition, and then create an object before calling its main():
if __name__ == "__main__":
instance = Matrix()
instance.main()
You've also got the assignments backwards in main(). It should read more like this:
info = open_file()
self.read_file(Info)
s = __str__(self)
print(s)
the open_file() method also has some issues. You want to create Info outside the scope of your loop so you know you've got it to return. Your comment indicates the Info is supposed to be the file pointer -- but it's not, as you wrote it. Open_File is the file pointer, and Info is the content of the file (at least, everything but the first line). Unless you're expecting a huge amount of data, it's probably easier to pass the contents -- or to combine open_file and read_file into the same function.
You also want to use the usual python pattern for opening and closing the files the with context manager - that will close your file for you.
Heres a quick and dirty version of Open_file and Read_file in one package.
def read_file(self):
#get the filename first
filename = None
while not filename:
user_fn = input("Enter a filename: ").lower()
if os.path.exists(user_fn):
filename = user_fn
else:
print ("Sorry that file doesn't exist!")
# 'with' will automatically close the file for you
with open(filename, 'rt') as filepointer:
# file objects are iterable:
for line in filepointer:
a, b = map(int, line.split())
self._matrix.setdefault(a, set()).add(b)
self._matrix.setdefault(b, set()).add(a)
I'm not clear what self._matrix.setdefault(a, set()).add(b) is supposed to be doing for you here, but in syntactic terms you can simply the structure to "get the filename, open with with, iterate over it"
Related
I am currently working on an inventory system that I have mocked up so far.
This is the following code:
import csv
class start_store:
def __init__(self):
self.name = self.ask()
self.options = self.ask_options()
def ask(self):
while 1:
name = input("What is your name?\n")
if name == "":
print("Ha! You have to enter a name!")
else:
print("Welcome to the Shepherdstown Bake Shop " + name)
return name
def ask_options(self):
while 1:
option = input('''What would you like to do? \n1. Add a Item: \n2. Delete a Item:\n3. Edit an Item: \n4. View Inventory \n5. End Program\n''')
if option == "4":
print("Here is the following inventory we have " + self.name)
items = CsvReader()
items.make_dict_items()
items.show_available()
break
else:
print("You have to enter a valid option " + self.name)
and the second class:
class CsvReader:
def __init__(self):
self.result = []
def make_dict_items(self):
with open("Items2.csv") as fp:
reader = csv.reader(fp)
labels = next(reader, None)
result = []
for row in reader:
row[0] = int(row[0])
row[1] = float(row[1])
row[2] = int(row[2])
pairs = zip(labels, row)
self.result.append(dict(pairs))
def show_available(self):
for item in self.result:
print(item)
obj = start_store() # create the instance
while 1:
obj.ask_options() # use the instance
From what I understand, I am able to run my code in IDLE based upon the last three lines in my second class, which initialize, and run. The program runs from : asking the user their name -> asking the user what they would like to do -> performing said task-> looping back to ask what to do.
I am confused on how I would implement a main method that runs my current program in that order? I understand how to make a main method, it being if __name__ == '__main__': , but what would I put under it? Would I have it run ask() like in the bottom of my lines? How do I add a main method that runs my program in this order in the sense that it is able to run now in IDLE without a main method?
I apologize if I am overlooking something, I am fairly new to Python and OOP.
Create 3 files: one file called csv_reader.py, one file called start_store.py, and a third called main.py. Place your CsvReader and start_store classes in the appropriate files, and in main.py write this:
from start_store import start_store
from csv_reader import CsvReader
if __name__ == "__main__" :
obj = start_store() # create the instance
while 1:
obj.ask_options() # use the instance
In your csv_reader.py file you should remove the code which creates an obj and the while loop - this should only be in the main.py file! This new file will include both of your classes (start_store and CsvReader) and run your main loop. You can run this with python main.py. It is worth noting that the file does not need to be called main.py (it can be called anything), and both classes could be included in the same file as the __main__ function, but this is just a simple example of how to separate your classes and then run them in a main loop.
With python whether you should have multiple classes in a file is a matter of opinion rather than a rule. If the classes are small then why not.
So all you need to do is put your if name == 'main': ahead of obj = start_store() ...
If the script is run from the command line to be able to cancel with Ctrl+C I like to use ...
def main()
obj = start_store() etc ...
return 0
if __name__ == "__main__":
try: # handle Ctrl+C
sys.exit(main())
except KeyboardInterrupt:
sys.exit(0)
I have a problem trying to access a variable from file a.py from a function in file b.py. I tried looking around the internet and could not find anything, or I don't know exactly how to look for what I need. I also tried to make another file and update the variable in file c.py, but file b.py still see's the first initialization of the variable. I tried to update the variable in file a.py and afterwards import a.py in the function in b.py.
File a.py
var = []
def run():
a.welcome()
while True:
menu = a.menu()
if menu == 1:
def retrieve_path(source_path):
"""The function takes 1 parameter and checks if the file name exist as well as the file path
Adds the csv data to a variable
source_path (str): Path against whom to check for validity
"""
if not source_path:
print("Invalid file name, Please try again\n")
return
else:
import os
isFile = os.path.isfile(source_path)
if not isFile:
print("Invalid file path\n")
return
else:
with open(source_path, "r") as csv_file:
csv_reader = csv.reader(csv_file, delimiter=',')
for line in csv_reader:
line = list(line)
var.append(line)
if __name__ == "__main__":
run()
file b.py
I tried like this but I get the first initialization of the variable var = []
I first updated var from file a.py and afterwards, I tried to use the function below inside file b.py but still the same result.
from a import var
from a import *
import a
def a_function():
from a import var
from a import *
import a
print(var)
print(a.var)
This prints the first initialization of var which = [] not after it was appended.
If I print var from a, from inside the function it prints it updated.
If I print var from a, from outside the function it prints it updated.
What I don’t understand is, why after updating it, and importing it into b, I still get the first initialization. Debugger didn’t help as well.
I can work around it by adding the function retrieve_path inside b.py and then appending the data in another variable inside file b.py but I would like to know why its not importing var updated with the data.
File b.py
var2 = []
def retrieve_path(source_path):
"""The function takes 1 parameter and checks if the file name exist as well as the file path
Adds the csv data to a variable
source_path (str): Path against whom to check for validity
"""
if not source_path:
print("Invalid file name, Please try again\n")
return
else:
import os
isFile = os.path.isfile(source_path)
if not isFile:
print("Invalid file path\n")
return
else:
with open(source_path, "r") as csv_file:
csv_reader = csv.reader(csv_file, delimiter=',')
for line in csv_reader:
line = list(line)
var.append(line)
var2.append(line)
The reason I didn't use Class if that was one of the solutions, is because I haven't learned that much about Classes and don't know how to use them properly for the time being.
I hope I was quite explicit and you understand my dilemma. Also, have in mind I just started learning Python, so a newbi explanation and solution are more than welcomed.
The correct way is to call the run function before accessing var. Either
import a
a.run
print(a.var)
or:
from a import var, run
run
print(var)
The import statement only runs the content of the module, not the functions declared in it.
The idiomatic way of running a script is indeed what you have in a.py:
if __name__ == "__main__":
run()
And the run function will be called if you use the file like a script with python a.py, because a file that is started directly by the interpretor will be named __main__. But when it is imported, it is named according to the file name. So here it would be a and not main. Said differently, run is never called when a.py is imported.
One possibility would be to end a.py with an unconditional call of run:
...
line = list(line)
var.append(line)
run()
It should be harmless because Python keeps track of the already imported module, and run should be called only once even if the module was imported from multiple places. Yet it would be an anti-pattern, because by convention import should have as few side effects as possible, while run seems to do plenty of actions.
Ok, this is just a part of the project which was for the school, which I finished, but I wanted to make this part with records a little bit different than I've done for the grade. If some function dont make sense, its because the project it is not finished. My only concerned is towards records variable.
main.py
import tui, csv
records = []
def run():
tui.welcome()
while True:
menu = tui.menu()
if menu == 1:
def retrieve_path(source_path):
"""The function takes 1 parameter and checks if the file name exist as well as the file path
Adds the csv data to a variable
source_path (str): Path against whom to check for validity
"""
if not source_path:
print("Invalid file name, Please try again\n")
return
else:
import os
isFile = os.path.isfile(source_path)
if not isFile:
print("Invalid file path\n")
return
else:
with open(source_path, "r") as csv_file:
csv_reader = csv.reader(csv_file, delimiter=',')
for line in csv_reader:
line = list(line)
records.append(line)
tui.started("Data Loading")
retrieve_path(tui.source_data_path())
tui.completed("Data Loading")
if menu == 2:
tui.started("Retrieving data")
process_menu = tui.process_type()
tui.completed("Retrieving data")
if process_menu == 1:
tui.started("Retrieving entity name")
tui.entity_name()
tui.completed("Retrieving entity name")
if process_menu == 2:
tui.started("Retrieving entity details")
entity, cols = tui.entity_details()
tui.list_entity(entity, cols)
tui.completed("Retrieving entity details")
if menu == 3:
print(tui.main_records)
if menu == 4:
break
if __name__ == "__main__":
run()
Second file is:
tui.py
def welcome():
message = "System Management"
print("*" * len(message))
print(message)
print("*" * len(message))
def menu():
main_menu = "-"
while main_menu != "0":
if main_menu == "-":
print('Main Menu:'
'\n1. Load Data'
'\n2. Process Data'
'\n3. Visualise Data'
'\n4. Save Data'
'\n0. Exit')
elif main_menu in "1234":
return int(main_menu)
elif main_menu not in "1234":
error(main_menu)
return None
else:
print('Main Menu:'
'\n1. Load Data'
'\n2. Process Data'
'\n3. Visualise Data'
'\n4. Save Data'
'\n0. Exit')
main_menu = input()
def started(operation):
print("{} has started.\n".format(operation))
def completed(operation):
print("{} has completed.\n".format(operation))
def error(error_msg):
print("Error! {} is not a valid option.".format(error_msg))
def source_data_path():
print("Please enter the path to the source data file:")
source_path = input()
if ".csv" not in source_path:
return None
else:
return source_path
def process_type():
process_menu = "-"
while process_menu != "0":
if process_menu == "-":
print('Process Menu:'
'\n1. Retrieve entity'
'\n2. Retrieve entity details'
'\n3. Categorise entities by type'
'\n4. Categorise entities by gravity'
'\n5. Summarise entities by orbit'
'\n6. Return to Main Menu')
elif process_menu == "6":
menu()
return None
elif process_menu in "12345":
return int(process_menu)
elif process_menu not in "12345":
error(process_menu)
return None
else:
print('Process Menu:'
'\n1. Retrieve entity'
'\n2. Retrieve entity details'
'\n3. Categorise entities by type'
'\n4. Categorise entities by gravity'
'\n5. Summarise entities by orbit'
'\n6. Return to Main Menu')
process_menu = input()
def entity_name():
entity = input("Please enter the name of an entity: ")
return entity
def entity_details():
entity = input("Please enter the name of an entity: ")
indexes = input("Please enter the indexes number (e.g. 0,1,5,7):\n")
return entity, list(indexes)
Please have
First time I did the project I added def retrieve_path(source_path): to tui.py and it worked fine.
What I don't really understand is why is the variable records being appended to, I can print it from within run and outside of run function, but in tui.py i get only records = [] and how to solve this without creating the function retrieve_path in tui.py
This is what it was asked of us at the time being and it was not my personal choice to do it like this.
I am sorry for not pasting everything here and mistyping some parts like == _ main _ .
I'm new to python and was wondering what am i missing in my code.
I want to build a class that receives 3 letter airport destination and origin, and prints out if it's in the text file
I appreciate your help !
class departure:
def __init__(self, destfrom, destto):
self.destfrom = destfrom
self.destto = destto
def verdest(self,dest):
flag = 0
destinations = ["JFK","AMS"]
for i in destinations:
if i == dest:
flag = i
return flag
if verdest() in open('airportlist.txt').read():
print("true")
There are a few changes you need to make. if i == dest: is checking if JFK is equal to the file contents, you probably mean in. Then you have a class but you never initialize it.
class departure:
def __init__(self, destfrom, destto):
self.destfrom = destfrom
self.destto = destto
def verdest(self,dest):
flag = 0
destinations = ["JFK","AMS"]
for i in destinations:
if i in dest: # change to in
flag = i
return flag
d = departure(['BWI'],['AMS'])
f = open('airportlist.txt','r')
flag = d.verdest(f.read()) #find last airport that was in file, could modify this to return list
if flag:
print("true" + flag)
else:
print('false')
f.close() #close the file
read reads the lines of a file into a single string.
If you use readlines instead you will get a list of lines in the file.
Then you can see if an individual code is in these lines.
Without a class, like this:
def verdest(self, dest):
flag = 0 # note - not used!
destinations = open('airportlist.txt').readlines()
return dest in destinations
if verdest("LGW"):
print("true")
If you want to store the two airport names in the class and look them up in a file later one, save the three letter codes as you do, but pass the filename contents to the checking function?
class departure:
def __init__(self, destfrom, destto):
self.destfrom = destfrom
self.destto = destto
def verdest(self, destinations):
return self.destfrom in destinations and self.destto in destinations
Then make a class and use it:
places = departure("JFK","AMS")
#This makes your class, and remembers the variables in member variables
if places.verdest(open('airportlist.txt').readlines()):
#In this member function call, places remembers the member variable set up above
print("true")
Now, you could read the file in the __init__ method of the class, rather than every time you want to check.
You are missing an argument in verdest() function call.
This question already has an answer here:
'int' object is not callable in python
(1 answer)
Closed 5 years ago.
I'm getting a TypeError: 'list' object is not callable but I can't see where the usual answer of use list[] instead of list() applies. I don't seem to be using either notation, just calling functions on the list. I'm quite stuck and could use some help here
import scheduler
def main():
sched = scheduler.Scheduler()
sched.line_list("/home/scabandari/Desktop/threads.txt") # Error is caused by this line
# sched.create_processList()
if __name__ == "__main__":
main()
scheduler.py:
import process
class Scheduler:
def __init__(self):
self.line_list = []
self.process_list = []
pass
# populates line_list[] from "/location/.txt" file, each line reps a process object
def line_list(self, file):
f = open(file)
getlines = f.readlines()
for line in getlines:
self.line_list.append(line)
self.line_list.pop(0)
# populates process_list[] from line_list[]
def process_list(self):
for line in self.line_list:
temp_arr = line.split()
self.process_list.append(process.Process(temp_arr[0], temp_arr[1],
temp_arr[2], temp_arr[3]))
for proc in self.process_list:
proc.print_process()
Know that when you define your class object named Scheduler as follows
class Scheduler:
def __init__(self):
self.line_list = []
self.process_list = []
def line_list(self, file):
f = open(file)
getlines = f.readlines()
for line in getlines:
self.line_list.append(line)
self.line_list.pop(0)
...
and then instantiate it, i.e.
inst = Scheduler()
the definition you have done of your method line_list, is overriden by the post-instantiation execution of __init__, which turns it into a list.
Which means that, as melpomene mentions in comments,
you need to decide whether you want line_list to be a method or a list. It can't be both.
Thus, what you may want to do is renaming your method, furthermore giving it a name representative of what it actually does, e.g.
...
def populate_line_list(self, file):
'''
Method which populates line_list from "/location/.txt" file,
each line reps a process object
'''
f = open(file)
getlines = f.readlines()
for line in getlines:
self.line_list.append(line)
self.line_list.pop(0)
f.close() #do not forget to close your file, or use a with-statement
...
Finally you will be able to do
import scheduler
def main():
sched = scheduler.Scheduler()
sched.populate_line_list("/home/scabandari/Desktop/threads.txt")
if __name__ == "__main__":
main()
I am new to programming and self taught. I have used Stack Exchange to find answers to many of my questions without ever needing to ask (it is a great community), but I cannot seem to find the answer to this anywhere. I apologize if this is a duplicate.
I am trying to assign a method to a variable, but I want to save it to a text file for access later. I am using open() to access the text file and eval() to change it from a string when loading the information. I just cannot figure out how to do the opposite.
from random import randint
class Example (object):
def __init__(self):
self.name = ""
self.lucky_number = ""
def create_person(self):
self.name = input("What is your name?")
self.lucky_number = randint(1,10)
save_person = [self.name, self.lucky_number]
with open("example.txt", "w") as f:
for i in save_person:
f.write(i + '\n')
def load_person(self):
with open("example.txt", 'r') as f:
person_list = f.readlines()
if len(person_list) <= 1:
create_person()
else:
self.name = person_list[0].strip('\n')
self.lucky_number = eval(person_list[1].strip('\n'))
person = Example()
person.load_person()
I want to keep the randint(1,10) part because I want to reuse the function, but I may change the value to something else later depending on user selection (such as changing self.lucky_number = randint(1,10) to self.lucky_number = randint(1,30)).
I know I can just change it to self.lucky_number = randint(1,var) and then save the value of var instead, but it made me wonder if the way I'm trying is possible.
Thanks in advance for any assistance. I am using Python 3.5.
Edit: For clarification I am looking to store the actual function, i.e. randint(1,10), in the text file, not the value of the function.
EDIT 2: I am going to close this as answered because I found a way to do what I needed, but it is not a direct way.
I was able to find a way to accomplish what I was looking for, but it is a roundabout way. I changed the call to the function into a string, then created a new class variable that calls the variable with the function string. The other class variable meant to run the function now has eval() around it and calls the new class variable I created. I save the new class variable instead.
from random import randint
# Now a string instead of a function call
prog = "randint(1,10)"
class Example (object):
def __init__(self):
self.name = ""
"""Added self.temp to grab the string from outer
variable and will change self.temp to get the desired
functions as strings"""
self.temp = prog
"""self.lucky_number grabs new class variable and
eval() turns it into callable function"""
self.lucky_number = eval(self.temp)
def create_person(self):
self.name = input("What is your name?")
self.temp = prog
self.lucky_number = eval(self.temp)
""" Saves new class variable now and stores actual
function, eg randint(1,10)"""
save_person = [self.name, self.temp]
with open("example.txt", "w") as f:
for i in save_person:
f.write(str(i) + '\n')
def load_person(self):
with open("example.txt", 'r') as f:
person_list = f.readlines()
if len(person_list) <= 1:
self.create_person()
else:
self.name = person_list[0].strip('\n')
self.temp = person_list[1].strip('\n')
person = Example()
person.load_person()
Its roundabout, but gets the job done. I can change self.temp to whatever variable (formatted properly) I need and the code will work. If anyone can think of a direct way please let me know.