hi im in need of some help for some basic programming exercises im working through. here's the problem.
a) Write a function that returns the maximum value from a list of names. The list of names is passed to the the function, the function returns the 'max' string.(essentially get the name that comes first alphabetically)
b) Write a function that replaces a value in a list with a different one. The parameters of this function are the list, the position in the list of the value that needs to be replaced and the replacement value. Call this function with alist of names in main(). Check if the list was changed by displaying it in main() after the replace function was called. (arrange the list alphabetically.)
in all of this i have to create two main programs, one main program to set up the basics then another seperate function to be called in the main to execute the necessary steps. it needs to be written in python. im completely lost here. heres the list of names im dealing with
bob
Nate
ethel
frank
johnjacobjingleheimerschmidt
clarice
ptolmey
nefertiti
hess
michelle
algernon
For part a), read how to use list.sort(). For part b), read this previous question on how to replace items in a list.
Related
Recently for a course at University, our teacher asked us to re-create one of Kaggle's competitions. I chose to do this one.
I was able to follow the tutorial relatively well, until I reached the for loop they wrote to clean the text in the data frame. Here it is:
# Get the number of reviews based on the dataframe column size
num_reviews = train["review"].size
# Initialize an empty list to hold the clean reviews
clean_train_reviews = []
# Loop over each review; create an index i that goes from 0 to the length
# of the movie review list
for i in xrange( 0, num_reviews ):
# Call our function for each one, and add the result to the list of
# clean reviews
clean_train_reviews.append( review_to_words( train["review"][i] ) )
My problem is when they use 'xrange' in the loop, since that was never assigned to anything during the tutorial and is, therefore, returning an error when I try to run the code. I also checked the code provided by the author on github and they did the exact same thing. So, my question is: Is this simply a mistake on their end or am I missing something? If I am not missing anything, what should be in the place of'xrange'?
I've tried assigning the relevant dataframe column to a variable I can then use here, but I then get a TypeError, stating 'Series' object is not callable. My knowledge in Python is a bit elementary still, so I apologize if I am simply missing something obvious. Appreciate any help!
range and xrange are both python functions, the only thing, xrange is used only in python 2.
Both are implemented in different ways and have different characteristics associated with them. The points of comparison are:
Return Type:
Type 'list',
Type 'xrange'
Memory:
Big size,
Small size
Operation Usage:
As range() returns the list, all the operations that can be applied on the list can be used on it. On the other hand, as xrange() returns the xrange object, operations associated to list cannot be applied on them, hence a disadvantage.
Speed:
Because of the fact that xrange() evaluates only the generator object containing only the values that are required by lazy evaluation, therefore is faster in implementation than range().
More info:
source
You are probably having this issue because you are using python3.
Just use range function instead.
I got an answer to my task in python.But I had a dought that
what is the difference between the empty list inside the function and outside the function?
why i am asking this because, my expected output came while i am declaring the empty list outside the function but not inside the function. Also I dont know how the output value in my list (5230) came in my output ? first three output value i know what happening in my program but last value in my list i dont know how that value came ?
my task question is
A 10-SUBSTRING OF A NUMBER IS A SUBSTRING OF ITS DIGITS THAT SUM UPTO 10 ALSO BE IN A ORDERED SEQUENCE OF THE GIVEN STRING ?
THE STRING IS '3523014'
EXPECTED OUTPUT : ['352','523','23014','5230']
MY CODE USING RECURSION.
l=[]
def ten_str(s):
x,z,p=0,1,1
for i in s:
x+=eval(i)
if x==10:
l.append(s[:z])
ten_str(s[p:])
p+=1
z+=1
return l
print(ten_str('3523014'))
If you create the empty list inside the function, then each time the function is recursively called it will create a new empty list. Strings meeting the condition will be lost when that recursive call ends, rather than being added to the global list. I find http://pythontutor.com/ helps a lot with recursion exercises.
Based on your question, a 10-substring is a set of values in the original order of the list when added sum up to 10.
5+2+3+0 = 10. Your list 3523014 contains 5230
I have a dictionary created from a json file. This dictionary has a nested structure and every few weeks additional parameters are added.
I use a script to generate additional copies of the existing parameters when I want multiple "legs" added. So I first add the additional legs. So say I start with 1 leg as my template and I want 10 legs, I will just clone that leg 9 more times and add it to the list.
Then I loop through each of the parameters (called attributes) and have to clone certain elements for each leg that was added so that it has a 1:1 match. I don't care about the content so cloning the first leg value is fine.
So I do the following:
while len(data['attributes']['groupA']['params']['weights']) < legCount:
data['attributes']['groupA']['params']['weights'].append(data['attributes']['groupA']['params']['weights'][0])
while len(data['attributes']['groupB']['paramsGroup']['factors']) < legCount:
data['attributes']['groupB']['paramsGroup']['factors'].append(data['attributes']['groupB']['paramsGroup']['factors'][0])
while len(data['attributes']['groupC']['items']['delta']) < legCount:
data['attributes']['groupC']['items']['delta'].append(data['attributes']['groupC']['items']['delta'][0])
What I'd like to do is make these attributes all strings and just loop through them dynamically so that when I need to add additional ones, I can just paste one string into my list and it works without having another while loop.
So I converted it to this:
attribs = [
"data['attributes']['groupA']['params']['weights']",
"data['attributes']['groupB']['paramsGroup']['factors']",
"data['attributes']['groupC']['items']['delta']",
"data['attributes']['groupD']['xxxx']['yyyy']"
]
for attrib in attribs:
while len(eval(attrib)) < legCount:
eval(attrib).append(eval(attrib)[0])
In this case eval is safe because there is no user input, just a defined list of entries. Tho I wouldn't mind finding an alternative to eval either.
It works up until the last line. I don't think the .append is working on the eval() result. It's not throwing an error.. just not appending to the element.
Any ideas on the best way to handle this?
Not 100% sure this will fix it, but I do notice one thing.
In your above code in your while condition you are accessing:
data['attributes']['groupA']['params']['weights']
then you are appending to
data['attributes']['groupA']['params']['legs']
In your below code it looks like you are appending to 'weights' on the first iteration. However, this doesn't explain the other attributes you are evaluating... just one red flag I noticed.
Actually my code was working. I was just checking the wrong variable. Thanks Me! :)
I'm running into a confusing issue with a current project. Basically, I am analyzing a MIDI file byte by byte (yes, I have to do it this way). MIDI files are structured such that the data for any given event in a track is conveyed via a series of bytes called a 'message'. A MIDI device knows what type of message based on a status code, which is 1-3 bytes within the 'message' that have specific IDs for specific functions.
I need to be able to look through a MIDI file's data and record each 'message' as a self-contained object so that I can put them in sequence for later use. The problem I run into is that as I progress through the data, I need an efficient way to read each status code and match it with the function I've written that processes the data for that type of message. What I'm trying to do now is this:
First, at any given point in the overall MIDI file, I look at the next 3 bytes and compare them with my list of all of the possible 3 byte MIDI status codes. Here's my first problem. For all 3 byte status code (which is equivalent to 6 hexadecimal digits, which is the encoding that is often used in MIDI editing), the 5th-8th bits (aka the second hexadecimal digit) specifies the MIDI channel that the current message affects, which is variable and unpredictable. Since I can't predict the channel, I need to treat it as a wild card value. In other words, I need to somehow be able to take the 6 digits and ignore the 2nd when I reference it against my list of codes. I don't think I explained that well, so here's an example:
6 hex-digit code inside the file: Bn7800 where n is the channel number
List of 6 digit codes: ['Bn7800','Bn7900','FF2001','FF2F00',...]
I need to search through that list for the correct code while ignoring the 2nd digit since I have no way of telling what it is ahead of time.
My other issue is that once I have that code, I need to call the specific function that I've written that handles that particular status code. I've named all of the functions after the status code they correspond to, but the problem is, I don't know how to take the string that I find in the list above and use it to call a function. For instance:
I need: Bn7800
In the list, I find it! So I store it as a new variable called stat_code = 'Bn7800'.
But I can't then call my function in this way -> self.stat_code(data)
because stat_code isn't the name of the function I want. I want the function that's named after the value of stat_code.
I'm not sure how I can go about calling a function based on the value of a stored variable.
Sorry if this is confusing, I find it difficult to explain fully without trying to explain the whole MIDI file structure. Please ask me questions if something is unclear. Thanks!
EDIT: Here is some of the code:
self.event_status_codes = {'ff0002': ff_00_02,'ff01': ff_01,'ff02': ff_02,'ff03': ff03,'ff04': ff_04,'ff05': ff_05,'ff06': ff_06,'ff07': ff_07,'ff2001': ff_20_01,'ff2f00': ff_2f_00,'ff5103': ff_51_03,'ff5405': ff_54_05,'ff5804': ff_58_04,'ff5902': ff_59_02,'ff7f': ff_7f,'8n': _8n,'9n': _9n,'an': an,'bn': bn,'cn': cn,'dn': dn,'en': en,'bn7800': bn_78_00,'bn7900': bn_79_00,'bn7a': bn_7a,'bn7b00': bn_7b_00,'bn7c00': bn_7c_00,'bn7d00': bn7d00,'bn7e': bn_7e,'bn7f00': bn_7f_00,'f0': f0,'f7': f7}
if track_data[hbc:hbc+3] in self.event_status_codes:
status_code = track_data[hbc:hbc+3]
self.status_code(track_data)
For reference, track_data is the raw hexadecimal sequence that I'm parsing through and hbc is a simple pointer that iterates through the file one hex digit at a time. I posted the whole status code dictionary, but right now am mainly concerned about the 3 digit ones because they typically specify channel number. Also, it's technically a Python dictionary because I had to name each corresponding function something slightly different than the actual code to make it readable and functional, so you can ignore the values of each key in the dictionary.
I'm not sure how I can go about calling a function based on the value of a stored variable.
This is doable by referring to the function by name. In your question, you imply that you're calling the function on self, which makes it easier: you might be able to get the attribute containing the function pointer by using the getattr() function, and then call it:
stat_code = 'B67800'
func = getattr(self, f'function_name_{stat_code}')
value = func()
# do stuff with value
This also works for if your function is part of any other module - just replace self in that example with the name of the module you'd call it from.
If you need to call a globally-defined function (not part of a module), you might need to index into locals() or globals():
func = globals()[f'function_name_{stat_code}']
value = func()
I am using a package that has operations inside the class (? not sure what either is really), and normally the data is called this way data[package.operation]. Since I have to do multiple operations thought of shortening it and do the following
list =["o1", "o2", "o3", "o4", "o5", "o6"]
for i in list:
print data[package.i]
but since it's considering i as a string it doesnt do the operation, and if I take away the string then it is an undefined variable. Is there a way to go around this? Or will I just have to write it the long way?.
In particular I am using pymatgen, its package Orbital and with the .operation I want to call specific suborbitals. A real example of how it would be used is data[0][Orbital.s], the first [0] denotes the element in question for which to get the orbitals s (that's why I omitted it in the code above).
You can use getattr in order to dynamically select attributes from objects (the Orbital package in your case; for example getattr(Orbital, 's')).
So your loop would be rewritten to:
for op in ['o1', 'o2', 'o3', 'o4', 'o5', 'o6']:
print(data[getattr(package, op)])