I had an identical problem with my other laptop, which led me to get this new one (new in the NBC after Friends sense) -- the interpreter would hang on some kind of nested iteration, and even freeze up and/or go berserk if left to its own devices. In this case, I CTRL+C'd after about five seconds. The interpreter said it stopped at some line in the while loop, different each time, indicating that it was working but at a slooooooooooow pace. Some test print statements seemed to show some problem with the iteration controls (the counter and such).
Is it a CPU problem, or what?
from __future__ import print_function
import sys
# script is a useless dummy variable, setting captures the setting (enc or dec), steps captures the number of lines.
script, setting, steps = sys.argv
# Input handling bloc.
if setting not in ('enc', 'dec'):
sys.exit("First command line thing must either be 'enc' or 'dec'.")
try:
steps = int(steps)
except:
sys.exit("Second command line thing must be convertable to an integer.")
# Input string here.
string_to_convert = raw_input().replace(' ', '').upper()
if setting == 'enc':
conversion_string = ''
counter = 0
while len(conversion_string) < len(string_to_convert):
for char in string_to_convert:
if counter == steps:
conversion_string += char
counter = 0
counter += 1
steps -= 1
print(conversion_string)
Depending on the starting value of steps its possible for counter and steps to never be equal, which means conversion_string is never altered, so it is always shorter than string_to_convert and the loop never ends.
A naive example is, let steps=-1, since counter starts at 0 and increments, and steps always decrements, they will never be equal.
Actually, on further inspection, if steps is less than len(string_to_convert) this will always end in an infinite loop.
Consider:
steps=2
string_to_convert="Python"
The first iteration of the for loop will iterate counter to 2 and fetch the "t"; now steps = 1, conversion_string="t"
Next for loop will iterate counter to 1, fetch the "y"; now steps = 0, conversion_string="ty"
for loop iterates counter to 0, fetch the "P"; now steps = -1, conversion_string="tyP"
Now, steps = -1, counter can never equal it, for loop ends without changing conversion_string.
Step 4 repeats while decreasing steps without any ability to quit the while loop.
Thus, why it sometimes works and sometimes doesn't.
Related
I might be asking a simple question. I have a python program that runs every minute. But I would like a block of code to only run once the condition changes? My code looks like this:
# def shortIndicator():
a = int(indicate_5min.value5)
b = int(indicate_10min.value10)
c = int(indicate_15min.value15)
if a + b + c == 3:
print("Trade posible!")
else:
print("Trade NOT posible!")
# This lets the processor work more than it should.
"""run_once = 0 # This lets the processor work more than it should.
while 1:
if run_once == 0:
shortIndicator()
run_once = 1"""
I've run it without using a function. But then I get an output every minute. I've tried to run it as a function, when I enable the commented code it sort of runs, but also the processing usage is more. If there perhaps a smarter way of doing this?
It's really not clear what you mean, but if you only want to print a notification when the result changes, add another variable to rembember the previous result.
def shortIndicator():
return indicate_5min.value5 and indicate_10min.value10 and indicate_15min.value15
previous = None
while True:
indicator = shortIndicator()
if previous is None or indicator != previous:
if indicator:
print("Trade possible!")
else:
print("Trade NOT possible!")
previous = indicator
# take a break so as not to query too often
time.sleep(60)
Initializing provious to None creates a third state which is only true the first time the while loop executes; by definition, the result cannot be identical to the previous result because there isn't really a previous result the first time.
Perhaps also notice the boolean shorthand inside the function, which is simpler and more idiomatic than converting each value to an int and checking their sum.
I'm guessing the time.sleep is what you were looking for to reduce the load of running this code repeatedly, though that part of the question remains really unclear.
Finally, check the spelling of possible.
If I understand it correctly, you can save previous output to a file, then read it at the beginning of program and print output only if previous output was different.
The following code will gather data from an API and the try/except clause will help to handle several errors (from authentication, index, anything).
There's only one error (an authentication error) that I'm using the while True to repeat the API call to make sure I get the data and it will after a try or two. However if by any means I get another error, it'll be infinitely looping and I can't break it so it goes to the next iteration. I tried to create a counter and if the counter reaches to a number then (pass or continue or break) but it's not working.
## Create a array to loop to:
data_array_query = pd.date_range(start_date,end_date,freq='6H')
#This is my idea but is not working
#Create a counter
counter = 0
#Loop through the just created array
for idx in range(len(data_array_query)-1):
## If counter reaches move on to next for loop element
while True:
if counter>=5:
break
else:
try:
start_date = data_array_query[idx]
end_date = data_array_query[idx+1]
print('from',start_date,'to',end_date)
df = api.query(domain, site_slug, resolution, data_series_collection, start_date=str(start_date), end_date=str(end_date), env='prod', from_archive=True, phase='production').sort_index()
print(df.info())
break
except Exception as e:
print(e)
counter +=1
print(counter)
So the output of running this code for a couple of days show that when it runs 5 times (that's the counter max I set up) it does break but it breaks the whole loop and I only want it to move to the next date.
Any help will be appreciated,
You need to use a break statement to get out of a while True loop. pass and continue work for for loops that have a fixed number of iterations. While loops can go on forever (hence the different names)
I'm trying to increase the count of an integer given that an if statement returns true. However, when this program is ran it always prints 0.I want n to increase to 1 the first time the program is ran. To 2 the second time and so on.
I know functions, classes and modules you can use the global command, to go outside it, but this doesn't work with an if statement.
n = 0
print(n)
if True:
n += 1
Based on the comments of the previous answer, do you want something like this:
n = 0
while True:
if True: #Replace True with any other condition you like.
print(n)
n+=1
EDIT:
Based on the comments by OP on this answer, what he wants is for the data to persist or in more precise words the variable n to persist (Or keep it's new modified value) between multiple runs times.
So the code for that goes as(Assuming Python3.x):
try:
file = open('count.txt','r')
n = int(file.read())
file.close()
except IOError:
file = open('count.txt','w')
file.write('1')
file.close()
n = 1
print(n)
n += 1
with open('count.txt','w') as file:
file.write(str(n))
print("Now the variable n persists and is incremented every time.")
#Do what you want to do further, the value of n will increase every time you run the program
NOTE:
There are many methods of object serialization and the above example is one of the simplest, you can use dedicated object serialization modules like pickle and many others.
If you want it to work with if statement only. I think you need to put in a function and make to call itself which we would call it recursion.
def increment():
n=0
if True:
n+=1
print(n)
increment()
increment()
Note: in this solution, it would run infinitely.
Also you can use while loop or for loop as well.
When you rerun a program, all data stored in memory is reset. You need to save the variable somewhere outside of the program, on disk.
for an example see How to increment variable every time script is run in Python?
ps. Nowadays you can simply do += with a bool:
a = 1
b = True
a += b # a will be 2
I have 5 players where they throw dice. We cannot use any external input such as onclick action or something.
How do I make the computer decide whether it is good to stop throwing? The stopping criteria is either you didn't throw 1,5 or straight or triples or higher. Everything counts as a point and if you hit something, lets say triple sixes you now can decide whether you throw again, but without these three dice. But if you fail to hit anything on the next throw, you lose every point you've got in the section. Or keep the sixes, which gives you 600 points.
def game(length, output = True):
round_no = 0
avg_pts = 0
player_points[0,0,0,0,0]
while output:
round_no += 1
for i in range 5:
lock = true
while lock:
dice_throw(number_of_throws)
def dice_throw(number_of_throws):
throw_values = []
for i in range(number_of_throws):
throw_values.append(randint(1,6))
throw_values.sort()
for i in range(throw_values)
How can I make a mechanism that decides if its good to continue throwing or not?
I have a program that looks something like (this is a silly example to illustrate my point, what it does is not very important)
count = 0
def average(search_term):
average = 0
page = 0
current = download(search_term, page)
while current:
def add_up(downloaded):
results = downloaded.body.get_results()
count += len(results)
return sum(result.score for result in results)
total = average*count
total += add_up(current)
average = total/count
print('Average so far: {:2f}'.format(average))
page += 1
current = download(search_term, page)
If I have the cursor on any of the lines 8–11 and press a key combination I want Emacs to copy or kill the add_up function, and then I want to move the cursor to line 2 and press a key combination and paste the function there, with the correct level of indentation for the context it is pasted in.
Is this possible, and if so, how would I do that?
With python-mode.el py-kill-def and yank would do the job.
However, there are some restrictions. py-kill-def must be called from inside def in question. So needs to go upward from line 11 first.
Also indenting after insert poses some problems: as indent is syntax, sometimes Emacs can't know which indentation is wanted. In example below have an indent of 4 first and of 8 in add_up probably is not wanted - however it's legal code. After indenting first line in body of add_up, py-indent-and-forward should be convenient for the remaining.
def average(search_term):
average = 0
def add_up(downloaded):
results = downloaded.body.get_results()
count += len(results)
return sum(result.score for result in results)
page = 0
current = download(search_term, page)
while current:
total = average*count
total += add_up(current)
average = total/count
print('Average so far: {:2f}'.format(average))
page += 1
current = download(search_term, page)
For this type of thing I usually use expand-region, which I choose to bind to C-=.
Using your example I can select the add_up() function by pressing C-= once, kill the region normally (C-k), move to line 2, and yank as usual (C-y).
Depending on what else you have configured for Python you may have to clean up some whitespace, or it may get cleaned up for you. For example, aggressive-indent would be helpful.
One manual option would be to reindent the pasted code with something like C-x C-x M-\.
I've been using smart-shift (available in Melpa) for this sort of thing. global-smart-shift-mode to enable (beware, it binds keys). Select the block you want to move (I'd use expand-region like Chris), and the default keybind C-S-c <arrow> starts moving it. Once you're shifting, the arrows (without C-S-c) shift further. Horizontal shifts use the major mode's indent offset (python-indent-offset for python.el).