I have a list of words. Each word has a numeric value.
'(("Home" 15)("Baby" 20) ("Mother" 28)...)).
I have to write a program which gets something like that:
(function-name "[Home (Baby3) 2] Mother"))
and to calculate their value.
Each word start with upper-case and all the other words in the word is lower-case.
Each word get its value from the list above.
Each word needs to be multiplied by the following number. If there is no number, then 1.
In the example above:
"[Home (Baby3) 2] Mother" = Home*1 + (Baby*3)*2 +Mother*1=15*1+20*3*2+28=163
I have no idea how to start this. Any ideas?
I start to write the code.
But, I dont know how to deal with 2 parenthesis [ , for eaxmple
[Home [Baby3] 2].
How can I know if ] clost the first or the second? (without use something like counter and set!)
Consider breaking the problem down into stages. One possible decomposition would be:
Figure out how to take arbitrary strings and parse them into data structures. e.g. given "[Home (Baby3) 2] Mother", write a parsing function that turns this into the more digestible, structured value '((Home (Baby 3) 2) Mother) or some variation of this.
Given such a structured value, write a function to interpret it based on the rules you described in your question.
Do you know how to do either of these?
Related
I will state the obvious that I am a beginner. I should also mention that I have been coding in Zybooks, which affects things. My textbook hasn't helped me much
I tried sub_lyric= rhyme_lyric[ : ]
Zybooks should be able to input an index number can get only that part of the sentence but my book doesnt explain how to do that. If it throws a [4:7] then it would output cow. Hopefully I have exolained everything well.
You need to set there:
sub_lyric = rhyme_lyric[start_index:end_index]
The string is as a sequence of characters and you can use string slicing to extract any sub-text from the main one. As you have observed:
sub_lyric = rhyme_lyric[:]
will copy the entire content of rhyme_lyric to sub_lyric.
To select only a portion of the text, specify the start_index (strings start with index 0) to end_index (not included).
sub_lyric = rhyme_lyric[4:7]
will extract characters in rhyme_lyric from position 4 (included) to position 7 (not included) so the result will be cow.
You can check more on string slicing here: Python 3 introduction
Question:
Fill in the function body for the Python3 function longestWord (you should leave the function header as it appears).
The function takes a single input argument which we assume is a list of strings, with each string forming one English word. The output should be a word from the list which has the greatest number of letters.
You must use a for loop to write this function.
Answer:
def longestWord(listOfWords):
biggestWord = listOfWords[0]
biggestNum = len(biggestWord)
for word in listOfWords:
num = len(word)
if num>biggestNum:
biggestNum=num
biggestWord=word
return biggestWord
print(longestWord(["Hello", "Goodbye"]))
I understand the first three lines. It takes the first value in the list and saves the length of the word inputted. However i don't understand the rest of the code. How does it compare the two inputted words to output the longest one. What is num and word?. Thank you.
I'd like to inform you that this question is about Python3 and not C++. Anyways, what the code is doing is it's taking the first word and stores it in a variable called biggestWord. and storing the length of biggestWord in a variable called biggestNum. Then for each word in listOfWords, it stores the word in a variable called word and stroing the length of it in variable called num. Then it compares num and biggestNum. If the length of some word i.e. num is bigger than the biggest length up until now, i.e. biggestNum, then it puts num in biggestNum to indicate that that's the biggest number up until now. and puts word in biggestWord replacing the old word. Then it returns the word with the biggest length, i.e. biggestWord.
let me explain better what I mean in the title.
Examples of strings where to search (i.e. strings of variable lengths
each one is an element of a list; very large in reality):
STRINGS = ['sftrkpilotndkpilotllptptpyrh', 'ffftapilotdfmmmbtyrtdll', 'gftttepncvjspwqbbqbthpilotou', 'htfrpilotrtubbbfelnxcdcz']
The substring to find, which I know is for sure:
contained in each element of STRINGS
is also contained in a SOURCE string
is of a certain fixed LENGTH (5 characters in this example).
SOURCE = ['gfrtewwxadasvpbepilotzxxndffc']
I am trying to write a Python3 program that finds this hidden word of 5 characters that is in SOURCE and at what position(s) it occurs in each element of STRINGS.
I am also trying to store the results in an array or a dictionary (I do not know what is more convenient at the moment).
Moreover, I need to perform other searches of the same type but with different LENGTH values, so this value should be provided by a variable in order to be of more general use.
I know that the first point has been already solved in previous posts, but
never (as far as I know) together with the second point, which is the part of the code I could not be able to deal with successfully (I do not post my code because I know it is just too far from being fixable).
Any help from this great community is highly appreciated.
-- Maurizio
You can iterate over the source string and for each sub-string use the re module to find the positions within each of the other strings. Then if at least one occurrence was found for each of the strings, yield the result:
import re
def find(source, strings, length):
for i in range(len(source) - length):
sub = source[i:i+length]
positions = {}
for s in strings:
# positions[s] = [m.start() for m in re.finditer(re.escape(sub), s)]
positions[s] = [i for i in range(len(s)) if s.startswith(sub, i)] # Using built-in functions.
if not positions[s]:
break
else:
yield sub, positions
And the generator can be used as illustrated in the following example:
import pprint
pprint.pprint(dict(find(
source='gfrtewwxadasvpbepilotzxxndffc',
strings=['sftrkpilotndkpilotllptptpyrh',
'ffftapilotdfmmmbtyrtdll',
'gftttepncvjspwqbbqbthpilotou',
'htfrpilotrtubbbfelnxcdcz'],
length=5
)))
which produces the following output:
{'pilot': {'ffftapilotdfmmmbtyrtdll': [5],
'gftttepncvjspwqbbqbthpilotou': [21],
'htfrpilotrtubbbfelnxcdcz': [4],
'sftrkpilotndkpilotllptptpyrh': [5, 13]}}
I want to search for a query (a string) in a subject (another string).
The query may appear in whole or in parts, but will not be rearranged. For instance, if the query is 'da', and the subject is 'dura', it is still a match.
I am not allowed to use string functions like strfind or find.
The constraints make this actually quite straightforward with a single loop. Imagine you have two indices initially pointing at the first character of both strings, now compare them - if they don't match, increment the subject index and try again. If they do, increment both. If you've reached the end of the query at that point, you've found it. The actual implementation should be simple enough, and I don't want to do all the work for you ;)
If this is homework, I suggest you look at the explanation which precedes the code and then try for yourself, before looking at the actual code.
The code below looks for all occurrences of chars of the query string within the subject string (variables m; and related ii, jj). It then tests all possible orders of those occurrences (variable test). An order is "acceptable" if it contains all desired chars (cond1) in increasing positions (cond2). The result (variable result) is affirmative if there is at least one acceptable order.
subject = 'this is a test string';
query = 'ten';
m = bsxfun(#eq, subject.', query);
%'// m: test if each char of query equals each char of subject
[ii jj] = find(m);
jj = jj.'; %'// ii: which char of query is found within subject...
ii = ii.'; %'// jj: ... and at which position
test = nchoosek(1:numel(jj),numel(query)).'; %'// test all possible orders
cond1 = all(jj(test) == repmat((1:numel(query)).',1,size(test,2)));
%'// cond1: for each order, are all chars of query found in subject?
cond2 = all(diff(ii(test))>0);
%// cond2: for each order, are the found chars in increasing positions?
result = any(cond1 & cond2); %// final result: 1 or 0
The code could be improved by using a better approach as regards to test, i.e. not testing all possible orders given by nchoosek.
Matlab allows you to view the source of built-in functions, so you could always try reading the code to see how the Matlab developers did it (although it will probably be very complex). (thanks Luis for the correction)
Finding a string in another string is a basic computer science problem. You can read up on it in any number of resources, such as Wikipedia.
Your requirement of non-rearranging partial matches recalls the bioinformatics problem of mapping splice variants to a genomic sequence.
You may solve your problem by using a sequence alignment algorithm such as Smith-Waterman, modified to work with all English characters and not just DNA bases.
Is this question actually from bioinformatics? If so, you should tag it as such.
I am trying to produce the following:The new values of x and y are -4 and 7, respectively, using the disp and num2str commands. I tried to do this disp('The new values of x and y are num2str(x) and num2str(y) respectively'), but it gave num2str instead of the appropriate values. What should I do?
Like Colin mentioned, one option would be converting the numbers to strings using num2str, concatenating all strings manually and feeding the final result into disp. Unfortunately, it can get very awkward and tedious, especially when you have a lot of numbers to print.
Instead, you can harness the power of sprintf, which is very similar in MATLAB to its C programming language counterpart. This produces shorter, more elegant statements, for instance:
disp(sprintf('The new values of x and y are %d and %d respectively', x, y))
You can control how variables are displayed using the format specifiers. For instance, if x is not necessarily an integer, you can use %.4f, for example, instead of %d.
EDIT: like Jonas pointed out, you can also use fprintf(...) instead of disp(sprintf(...)).
Try:
disp(['The new values of x and y are ', num2str(x), ' and ', num2str(y), ', respectively']);
You can actually omit the commas too, but IMHO they make the code more readable.
By the way, what I've done here is concatenated 5 strings together to form one string, and then fed that single string into the disp function. Notice that I essentially concatenated the string using the same syntax as you might use with numerical matrices, ie [x, y, z]. The reason I can do this is that matlab stores character strings internally AS numeric row vectors, with each character denoting an element. Thus the above operation is essentially concatenating 5 numeric row vectors horizontally!
One further point: Your code failed because matlab treated your num2str(x) as a string and not as a function. After all, you might legitimately want to print "num2str(x)", rather than evaluate this using a function call. In my code, the first, third and fifth strings are defined as strings, while the second and fourth are functions which evaluate to strings.