João Portugal - 2 months ago 13

Python Question

Good afternoon,

I got a question for an assignment in python

it's almost correct but the last part which I can't figure out

`def create_line(letters,x,numElems):`

sizeofLetters=len(letters)

another_list = []

i=0

while(i!=numElems):

if(i+x*numElems==sizeofLetters):

break

another_list.append(letters[i+x*numElems])

i +=1

return another_list

def create_key(letters):

sizeofList = len(letters)

conjLetters = []

x=0

i=0

raiz = sqrt(sizeofList)

numTuples=raiz

if(isinstance(raiz,float)==True):

numTuples = int(raiz)+1

raiz = int(raiz)+1

numElems=sizeofList/raiz

while(x!=numTuples-1):

line = tuple(create_line(letters,x,numElems))

x+=1

conjLetters.append(line)

return tuple(conjLetters)

create_key receives a tuple of chars (E.g: ('A','B','C','D'). Transforms it into a tuple of tuples. The number of tuples is the square root of the size, rounded up always (4,1=5). The number of elements per tuple is assigned by dividing the len of tuple per number of tuples.

create_line appends each letter received to a list returning it with the condition of each list returned has a max of numElems per list.

create_key after that appends all lists (meanwhile transformed into a tuple) into a tuple of tuples returning it.

So my problem is when I do this code, if letters = ('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', ' ', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'X', 'Z', '.')

my output was supposed to be (('A', 'B', 'C', 'D', 'E'), ('F', 'G', 'H', 'I', 'J'), (' ', 'L', 'M', 'N', 'O'), ('P', 'Q', 'R', 'S', 'T'), ('U', 'V', 'X', 'Z', '.'), ())

without the final tuple, this only happens when the root is int (for example 25,36 etc)

Appreciate the help!

João

Answer

The result of `sqrt`

will always be a float (in case of 25, it's `5.0`

). That's why you always add 1 to the integer representation, which misrepresents the numbers in case the number is whole. Instead, use `math.ceil`

, which returns the next-highest integer, or the same number, if it's a whole number already:

```
from math import sqrt, ceil
...
def create_key(letters):
sizeofList = len(letters)
conjLetters = []
x = 0
i = 0
raiz = ceil(sqrt(sizeofList))
numTuples = raiz
numElems = sizeofList // raiz # Python 3 compatibility
while x != numTuples-1:
line = tuple(create_line(letters, x, numElems))
x += 1
conjLetters.append(line)
return tuple(conjLetters)
```