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# Asking for help in Python

Hi everyone, my question is that I need a program written in Python (but no problem if it's on other, I just need the idea) to operate some numbers on a n-term list. Like this: [a, b, c] a+b+c, a+b-c, a+b*c, a+b/c, a-b+c, a-b-c, ... and so on. If anyone knows a way to do that please let me know. Thanks.

4th Nov 2017, 3:50 PM
Álvaro Estévez López
4 ответов
+ 5
# With basic loops structure (could be shorwrited/improved using list iteration methods, and/or list comprehension notation, but basic way is better self-explaining): op = '+-*/' nb = [1,2,3] c = len(nb)-1 d = len(op) D = pow(d,c) i = 0 a = [] while (i<D): N = '' j = i for n in range(c): k = j%d j = j//d N = str(op[k])+N a.append(N) i += 1 print(a,'\n') b = [] for o in a: N = str(nb[0]) for i in range(c): N += o[i]+str(nb[i+1]) b.append(N) print(b,'\n') r = [] for e in b: r.append(eval(e)) print(e,'=',r[-1:][0])
4th Nov 2017, 4:24 PM
visph
+ 2
# I'm not posting this here for votes, just something to look at curiously (it works, but it annoyed me). from itertools import product,starmap varList = ["a", "b", "c"] formatString = "{}".join(varList) print(*starmap(formatString.format, product('+-/*', repeat=len(varList)-1))) # ----- long version of last line ------ r = len(varList)-1 p = product('+-/*', repeat = r) s = starmap(formatString.format, p) print(*s) # ----- explanation ----- # Any number of variables works with this method # formatString = "a{}b{}c" # p returns a tuple sequence with 2 repeats (16 tuples): ('+', '+',) ('+', '-') ... ('*', '*') # format() wants two parameters, p returns tuples, starmap expands tuples # *s expands the starmap object into its output
4th Nov 2017, 9:12 PM
Kirk Schafer
+ 1
You can loop through the list, right? The simplest way is: 1. On each iteration you can ask what operation to process (*, /, +, - ) 2. Keep the current result in a variable. 3. At the end print the result variable.
4th Nov 2017, 4:19 PM
Boris Batinkov
+ 1
##for getting the logic use @ Visph's idea.. ##i am giving a non-headeache method.. import itertools def findsubsets(S,m): ## change the m and try also for bigger no. of digits for i in set(itertools.permutations(S, m)) : e=eval('1'+i[0]+'2'+i[1]+'3') print('1'+i[0]+'2'+i[1]+'3 =',e) return None findsubsets("+/+/-*-*",2) ## author--> Sayan Chandra
4th Nov 2017, 5:46 PM
sayan chandra
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