this is not a programming question but a question about the IDLE. Is it possible to change the comment block key from '#' to something else?
here is the part that is not going to work:
array = []
y = array.append(str(words2)) <-- another part of the program
Hash = y.count(#) <-- part that won't work
print("There are", Hash, "#'s")
No, that isn't specific to IDLE that is part of the language.
EDIT: I'm pretty sure you want to use
y.count('#') # note the quotes
Remember one of the strengths of Python is portability. Writing a program that would only work with your custom version of the interpreter would be removing the strengths of the language.
As a rule of thumb anytime you find yourself thinking that solution is to rewrite part of the language you might be heading in the wrong direction.
You need to call count on the string not the list:
array = []
y = array.append(str(words2)) <-- another part of the program
Hash = y[0].count('#') # note the quotes and calling count on an element of the list not the whole list
print("There are", Hash, "#'s")
with output:
>>> l = []
>>> l.append('#$%^&###%$^^')
>>> l
['#$%^&###%$^^']
>>> l.count('#')
0
>>> l[0].count('#')
4
count is looking for an exact match and '#$%^&###%$^^' != '#'. You can use it on a list like so:
>>> l =[]
>>> l.append('#')
>>> l.append('?')
>>> l.append('#')
>>> l.append('<')
>>> l.count('#')
2
Related
This is what my code is at the moment and I was wondering if I can assign list values like this.(I'm making a quote generator.)
import random as random
quotes = []
authors = []
quotes[0] = "I have a new philosophy. I'm only going to dread one day at a time."
authors[0] = "Charles Schulz"
quotes[1] = "Reality is the leading cause of stress for those in touch with it."
...
authors[5577] = "Henry David Thoreau"
quotes[5578] = "Sometimes the cards we are dealt are not always fair. However you must keep smiling and moving on."
authors[5578] = "Tom Jackson"
x=random.randint(2,5577)
for y in range(0,5579,1):
print(quotes[y]+" "+author[y])```
You are getting index out of range error since you are trying to access elements from an empty array. You can either initialize the author and quotes list:
authors = [None] * 5579
quotes = [None] * 5579
or a better way to add elements to list would be using the append method.
authors = []
quotes = []
quotes.append("I have a new philosophy. I'm only going to dread one day at a time.")
authors.append("Charles Schulz")
...
quotes.append("Sometimes the cards we are dealt are not always fair. However you must keep smiling and moving on.")
authors.append("Tom Jackson")
for author, quote in zip(authors,quotes):
print("{} {}".format(author, quote))
As stated in the comments, if you create an empty list, you can't assign values with the [] operator, that's for referencing elements that already exist inside the list (so you can update or read them). For adding new values to an empty list we use the append method like this:
quotes = []
quotes.append("I have a new philosophy. I'm only going to dread one day at a time.")
print(quotes[0])
>>> "I have a new philosophy. I'm only going to dread one day at a time."
You can now modify it because it exists:
quotes[0] = "Reality is the leading cause of stress for those in touch with it."
print(quotes[0])
>>> "Reality is the leading cause of stress for those in touch with it."
If you try to access index 1 it will give you an IndexError because it only has index 0 (in my example).
From more on lists, the append() function suggests a roundabout alternative to what you're trying to do:
>>> quotes = []
>>> quotes[0:] = ["first quote"]
>>> quotes[1:] = ["second quote"]
>>> quotes
['first quote', 'second quote']
This requires that both left hand and right hand sides be lists, and makes sure that you can't access lists that haven't had anything assigned to them yet.
As I mentioned in the comment above, IndexError comes from the list not having that element, which prevents one from mistakenly doing something like quotes[55] and expecting it to work too early on.
You are doing quotes[0] and so on, while quotes being empty, does not contain an index 0, 1, etc. You should use append() function instead, to add elements to your list.
Or, if you really want to use quotes[0] and so on, then do
quotes = [None] * 5579
or
quotes = [''] * 5579
at the start of the program.
I am trying to write a Python program as following:
list_a = []
list_b = []
list_c = []
listName = str(input('insert list name: '))
listValue = int(input('insert value: '))
listName.append(listValue)
But unfortunately "listName.append()" won't work.
Using only IF functions as in:
if listName == 'list_a':
list_a.append(listValue)
is impractical because I am actually working with 600+ lists...
Is there any other way I could do to make something like this work properly??
Help is much appreciated!
Thank you very much in advance!!
When you're tempted to use variable names to hold data — like the names of stocks — you should almost certainly be using a dictionary with the data as keys. You can still pre-populate the dictionary if you want to (although you don't have to).
You can change your existing to code to something like:
# all the valid names
names = ['list_a', 'list_b', 'list_c']
# pre-populate a dictionary with them
names = {name:[] for name in names}
# later you can add data to the arrays:
listName = str(input('insert list name: '))
listValue = int(input('insert value: '))
# append value
names[listName].append(listValue)
With this, all your data is in one structure. It will be easy to loop through it, make summary statistics like sums/averages act. Having a dictionary with 600 keys is no big deal, but having 600 individual variables is a recipe for a mess.
This will raise a key error if you try to add a name that doesn't exists, which you can catch in a try block if that's a possibility.
Keep your lists in a dict. You could initialize your dict from a file, db, etc.
lists = {"GOOG": []}
listName = str(input('insert list name: '))
listValue = int(input('insert value: '))
lists.setdefault(listName,[]).append(listValue)
# Just a little output to see what you've got in there...
for list_name, list_value in lists.items():
print(list_name, list_value)
So, following Mark Meyer's and MSlimmer's suggestions above, I am using a dictionary of lists to simplify data input, which has made this section of my program work flawlessly (thanks again, guys!).
However, I am experiencing problems with the next section of my code (which was working before when I had it all as lists haha). I have a dictionary as below:
names = {'list_a':[5, 7, -3], 'list_b':[10, 12, -10, -10]}
Now, I have to add up all positives and all negatives to each list. I want it to have the following result:
names_positives = {'list_a': 12, 'list_b': 22}
names_negatives = {'list_a': -3, 'list_b': -20}
I have tried three different ways, but none of them worked:
## first try:
names_positives = sum(a for a in names.values() if a > 0)
## second try:
names_positives = []
names_positives.append(a for a in names.values() if compras > 0)
## third try:
names_positives = dict(zip(names.keys(), [[sum(a)] for a in names.values() if compra > 0]))
To be honest, I have no idea how to proceed -- I am getting errors due to mixing strings and integers in those lines, and I am not being able to work some way around this problem... Any help is much appreciated. It could result in a dictionary, in a list or even in only the total sum (as in the first try, under no better circumstances).
Cheers!
You can try this one:
I just added one line for your code to work.
list_a = ['a']
list_b = []
list_c = []
listName = str(input('insert list name: '))
listValue = int(input('insert value: '))
eval(listName).append(listValue)
the eval function evaluates the string into an actual python expression. It should be noted however that there are security issues regarding the use of eval. But for the exact question that you were trying to answer, this would be the easiest way that wouldn't require much refactoring of the existing code.
i have a tuple which looks like this b (u'3.7', 9023). i want to use it in the following statement :
if list(self.ballot_number) == msg.ballot_number and b in waitfor:
print "hello"
i have checked and the ballotnumber section of the if condition is worrking fine. it's the second part that's not returning true. the waitfor set looks like this : set([((u'3.0', 9002), (u'3.1', 9005), (u'3.2', 9008), (u'3.3', 9011), (u'3.4', 9014), (u'3.5', 9017), (u'3.6', 9020), (u'3.7', 9023))]).
The value of tuple are there in the set but they are not able to match it probably because of different data types. i don't want to split the tuple into individual elements as i have to use it collectively later in the code. How can i run my if statement?
building of set
waitfor = set()
print "in scout"
for a in self.acceptors:
print "acceptor",a
a = tuple(tuple(p) for p in self.acceptors)
waitfor.add(a)
print "waitfor",waitfor
The problem is that you’re not building the set that it seems you think you’re building, and as a result it can’t be used the way you want to use it.
Your code does this:
waitfor = set()
print "in scout"
for a in self.acceptors:
print "acceptor",a
a = tuple(tuple(p) for p in self.acceptors)
waitfor.add(a)
print "waitfor",waitfor
So, for each acceptor, you’re not adding that acceptor to the set, you’re adding the tuple of all acceptors to the set. You do this over and over, but because it’s a set, and you’re adding the same tuple over and over, you end up with just one element, that big tuple of all of the acceptors. Which is exactly what you see—notice the extra parentheses in your output, and the fact that if you print out len(waitfor) it’s just 1.
And this means that none of the p values you later check with p in waitfor are going to be in waitfor, because the only thing that’s actually in it is the giant tuple that contains all those pairs, not any of the pairs itself.
It’s like adding “The State of California” to a phonebook millions of times, instead of adding the millions of Californians, and then asking “Is Jerry Brown in the phonebook?” No, he’s not. There’s no bug in how you’re searching the phonebook; the bug was in creating the phonebook. So that’s the part you need to fix.
So, what you want is:
waitfor = set()
print "in scout"
for a in self.acceptors:
print "acceptor",a
waitfor.add(tuple(a))
print "waitfor",waitfor
Or, more simply, this one-liner:
print “in scout”
waitfor = set(tuple(p) for p in self.acceptors)
print “waitfor”, waitfor
Or, if your version of Python is new enough for set comprehensions (I think that means 2.7, but don’t quote me on that), it’s slightly more readable:
print “in scout”
waitfor = {tuple(p) for p in self.acceptors}
print “waitfor”, waitfor
You've got too many brackets in your set, so it's only looking for a single element.
len(waitfor)
# 1
If you try:
waitfor = set([(u'3.0', 9002), (u'3.1', 9005), (u'3.2', 9008), (u'3.3', 9011), (u'3.4', 9014), (u'3.5', 9017), (u'3.6', 9020), (u'3.7', 9023)])
Then your test:
(u'3.7', 9023) in waitfor
# True
Will work!
Hi wonder if someone can help I've converted to Python from Perl and for the most part I love it. However I struggle with regex in Python this is not as strong or easy as perl for anyway. How do I use a list of exemption values(exemptions_list) to search another list which is being iterated in a for loop. Problem is that the values in the for loop are slightly different from the search exemptions.
i.e. one of the exemptions is the string "default" but the variable coming in to be search is default_10 or default_20. Likewise none is the search pattern but the share is called none_20 etc. I don't really want to iterate over the search patterns as I am already iterating over the shares which come from another subprocess output. So basically it never finds the string as it is looking for default_20 rather than default. How can break down the variable coming in from shared_list so that python uses default from the variable to search again the strings in the exemptions_list. The share variable is as stated generated differently for different systems subprocess output.
Many thanks
in Perl it would be easy.
if ( $share =~ /^.*_[\d\d]/ && $share !~ /$cust_id|$exemptions/ ) {
Python:
exemption_list = "none temp swap container"
shares_list [' this is dynamic and comes in with values such as none_20 temp_20, testtmp etc ]'
def process_share_information(shares_list, customer_id):
for share in shares_list:
share_match = re.search(share, exemption_list)
if not share_match:
print 'we have found a potentially bad share not in exemptions'
Strips last _\d\d from string
re.sub(r'_\d\d$', '', string)
So to check for exemption do
>>> re.sub(r'_\d\d$', '', "none_20") in exemption_list
True
If searched words are in more general format than name_\d\d, iterate over exemptions instead.
>>> exemptions = "none temp swap container".split()
>>> shares_list = "this is dynamic and comes in with values such as none_20 asdfnone anonea temp_20, testtmp etc"
>>> for e in exemptions:
... print(e)
... print(e in shares_list)
... print(re.findall(r'\b\S*?{}\S*?\b'.format(e), shares_list))
... print()
...
none
True
['none_20', 'asdfnone', 'anonea']
temp
True
['temp_20']
swap
False
[]
container
False
[]
Or if you only need one result for whole string
>>> any(e in shares_list for e in exemptions)
True
I am fairly new at python (and programming in general, just started 2 months ago). I have been tasked with creating a program that takes a users starting string (i.e. "11001100") and prints each generation based off a set of rules. It then stops when it repeats the users starting string. However, I am clueless as to where to even begin. I vaguely understand the concept of cellular automata and therefore am at a loss as to how to implement it into a script.
Ideally, it would take the users input string "11001100" (gen0) and looks at the rule set I created and converts it so "11001100" would be "00110011" (gen1) and then converts it again to (gen3) and again to (gen4) until it is back to the original input the user provided (gen0). My rule set is below:
print("What is your starting string?")
SS = input()
gen = [SS]
while 1:
for i in range(len(SS)):
if gen[-1] in gen[:-2]:
break
for g in gen:
print(g)
newstate = {
#this is used to convert the string. we break up the users string into threes. i.e if user enters 11001100, we start with the left most digit "1" and look at its neighbors (x-1 and x+1) or in this case "0" and "1". Using these three numbers we compare it to the chart below:
'000': 1 ,
'001': 1 ,
'010': 0 ,
'011': 0 ,
'100': 1 ,
'101': 1 ,
'110': 0 ,
'111': 0 ,
}
I would greatly appreciate any help or further explanation/dummy proof explanation of how to get this working.
Assuming that newstate is a valid dict where the key/value pairs correspond with your state replacement (if you want 100 to convert to 011, newstate would have newstate['100'] == '011'), you can do list comprehensions on split strings:
changed = ''.join(newstate[c] for c in prev)
where prev is your previous state string. IE:
>>> newstate = {'1':'0','0':'1'}
>>> ''.join(newstate[c] for c in '0100101')
'1011010'
you can then use this list comp to change a string itself by calling itself in the list comprehension:
>>> changed = '1010101'
>>> changed = ''.join(newstate[c] for c in changed)
>>> changed
'0101010'
you have the basic flow down in your original code, you jsut need to refine it. The psuedo code would look something like:
newstate = dict with key\value mapping pairs
original = input
changed = original->after changing
while changed != original:
changed = changed->after changing
print changed
The easiest way to do this would be with the re.sub() method in the python regex module, re.
import re
def replace_rule(string, new, pattern):
return re.sub(pattern, new, string)
def replace_example(string):
pattern = r"100"
replace_with = "1"
return re.sub(pattern, replace_with, string)
replace_example("1009")
=> '19'
replace_example("1009100")
=> '191'
Regex is a way to match strings to certain regular patterns, and do certain operations on them, like sub, which finds and replaces patterns in strings. Here is a link: https://docs.python.org/3/library/re.html