Replacing or substituting in a python string does not work - string

I could almost solve all of my python problems thanks to this great site, however, now I'm on a point where I need some more and specific help.
I have a string fetched from a database which looks like this:
u'\t\t\tcase <<<compute_type>>>:\n\t\t\t\t{\n\t\t\t\t\tif (curr_i <= 1) Messag...
the string is basically plain c code with unix line endings and supposed to be treated in a way that the values of some specific variables are replaced by something else gathered from a Qt UI.
I tried the following to do the replacing:
tmplt.replace(u"<<<compute_type>>>", str(led_coeffs.compute_type))
where 'led_coeffs' is a namedtuple and its value is an integer. I also tried this:
tmplt = Template(u'\t\t\tcase ${compute_type}:\n\t\t\t\t{\n\t\t\t\t\tif (curr_i <= 1) Messag...)
tmplt.substitute(compute_type = str(led_coeffs.compute_type))
however, both approaches do not work and I have no idea why. Finally I was hoping to get some input here. Maybe the whole approach is not right and any hint on how to achieve the replacing in a good manner is highly appreciated.
Thanks,
Ben

str.replace (and other string methods) don't work in-place (string in Python are immutable) - it returns a new string - you will need to assign the result back to the original name for the changes to take effect:
tmplt = tmplt.replace(u"<<<compute_type>>>", str(led_coeffs.compute_type))
You could also invent your own kind of templating:
import re
print re.sub('<<<(.*?)>>>', lambda L, nt=led_coeffs: str(getattr(nt, L.group(1))), your_string)
to automatically lookup attributes on your namedtuple...

Related

Can I format variables like strings in python?

I want to use printing command bellow in many places of my script. But I need to keep replacing "Survived" with some other string.
print(df.Survived.value_counts())
Can I automate the process by formating variable the same way as string? So if I want to replace "Survived" with "different" can I use something like:
var = 'different'
text = 'df.{}.value_counts()'.format(var)
print(text)
unfortunately this prints out "df.different.value_counts()" as as a string, while I need to print the value of df.different.value_counts()
I'm pretty sure alot of IDEs, have this option that is called refactoring, and it allows you to change a similar line of code/string on every line of code to what you need it to be.
I'm aware of VSCode's way of refactoring, is by selecting a part of the code and right click to select the option called change all occurances. This will replace the exact code on every line if it exists.
But if you want to do what you proposed, then eval('df.{}.value_counts()'.format(var)) is an option, but this is very unsecured and dangerous, so a more safer approach would be importing the ast module and using it's literal_eval function which is safer. ast.literal_eval('df.{}.value_counts()'.format(var)).
if ast.literal_eval() doesn't work then try this final solution that works.
def cat():
return 1
text = locals()['df.{}.value_counts'.format(var)]()
Found the way: print(df[var].value_counts())

Questions regarding Python replace specific texts

I'm writing a script to scrape from another website with Python, and I am facing this question that I have yet to figure out a method to resolve it.
So say I have set to replace this particular string with something else.
word_replace_1 = 'dv'
namelist = soup.title.string.replace(word_replace_1,'11dv')
The script works fine, when the titles are dv234,dv123 etc.
The output will be 11dv234, 11dv123.
However if the titles are, dv234, mixed with dvab123, even though I did not set dvab to be replaced with anything, the script is going to replace it to 11dvab123. What should I do here?
Also, if the title is a combination of alphabits,numbers and Korean characters, say DAV123ㄱㄴㄷ,
how exactly should I make it to only spitting out DAV123, and adding - in between alphabits and numbers?
Python - making a function that would add "-" between letters
This gives me the idea to add - in between all characters, but is there a method to add - between character and number?
the only way atm I can think of is creating a table of replacing them, for example something like this
word_replace_3 = 'a1'
word_replace_4 = 'a2'
.......
and then print them out as
namelist3 = soup.title.string.replace(word_replace_3,'a-1').replace(word_replace_4,'a-2')
This is just slow and not efficient. What would be the best method to resolve this?
Thanks.

Erlang - Converting String to Binary

Consider this variable
X = "1_2_3_4",
How to I get X into a binary string format?
So like this
<<"1_2_3_4">>
I'm getting all manner of errors trying to figure it out.
Thanks in advance,
Snelly.
Use the built in conversion function.
list_to_binary(X).
Thanks Dave! I had a quite a complex function concatinating variables
and strings/integers/atoms etc.
In case you are interested:
convert(L) ->
convert(L, <<>>).
convert([], Bin) ->
Bin;
convert([H|T], Bin) ->
convert(T, <<Bin/binary, H>>).
(what I was thinking of as Strings) as lists! Confusing
I think the reason that it's confusing is because sometimes the shell prints out a list as a string and sometimes it doesn't. In my opinion, things would be much clearer if the shell always output a list as a list unless you specifically requested a string.

LibreOffice Basic: existing utilities for splitting strings?

I'm using the LibreOffice Basic language.
I'm wondering if there is any library anywhere I can use for splitting strings into arrays? For example, suppose I have the following string with items separated by an arbitrary number of spaces:
ABC DEF GHI
I'd like to split this string into an array called "item" with the following elements:
item(0) = "ABC"
item(1) = "DEF"
item(2) = "GHI"
I know how to produce these results in LibreOffice Basic using regular expressions or via iterating character-by-character through the original string, but I'm wondering if there are any existing functions or helper utilities I can use, so I don't have to "re-invent the wheel".
Internet searches have not yielded anything, but I could possibly have overlooked something.
Thank you in advance.
It looks like you will need to write your own function. There are several ideas at https://forum.openoffice.org/en/forum/viewtopic.php?f=9&t=33218.
If you will be doing a lot of string manipulation and the project is not too far along yet, then it might be worth considering another UNO-enabled language like Java or Python. In Python the code would be simply:
s = "ABC DEF GHI"
item = s.split()

How to save strings in matrixes in matlab

I want to have a matrix/cell, that has strings inside that I can access and use later as strings.
For instance, I have one variable (MyVar) and one cell (site) with names inside:
MyVar=-9999;
site={'New_York'; 'Lisbon'; 'Sydney'};
Then I want to do something like:
SitePosition=strcat(site{1},'_101'}
and then do this
save(sprintf('SitePosition%d',MyVar),);
This doesn't work at all! Is there a way to have strings in a matrix and access them in order to keep working with them if they were a string?
This:
MyVar=-9999; site={'New_York'; 'Lisbon'; 'Sydney'};
SitePosition = strcat(site{1},'_101');
save(sprintf('SitePosition%d',MyVar));
Works fine and yields SitePosition-9999.mat, note the syntax changes in lines 2 and 3.
Is there something else you're expecting?
EDIT: Based on your comment
Check out the documentation for save regarding saving specific variables
New example:
MyVar=-9999;
site={'New_York'; 'Lisbon'; 'Sydney'};
SitePosition = strcat(site{1},'_101');
save(SitePosition,'MyVar');
Creates New_York_101.mat with only the variable MyVar in it.

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