Is the below code valid in python or its not possible to extract variable in python and perform checks on it in one line?
def method1(self,some_text):
"""For illustration purpose it returns a hard coded value"""
return (1,2)
if x = method1("Hello") and x[0] == 1 and x[1] = 2:
print("This is it {},{}".format(x[0],x[1]))
elif x = method1("World") and x[0] == 3 and x[1] = 4:
print("This is it, second {},{}".format(x[0],x[1]))
elif x = method1("The") and x[0] == 5 and x[1] = 6:
print("This is it, third {},{}".format(x[0],x[1]))
else:
print("No match")
Currently I have this if condition for multiple attribute to check. Since python throws error because its not a valid syntax, I have to declare all such property above the if statement and so many attributes being declared in the local block.
Any better way or suggestion, to have extract the variable and have checks in one line as well as use the attribute within if block?
Check this:
def method1(some_text):
"""For illustration purpose it returns a hard coded value"""
return (1,2,3)
def printres(x):
for i in x:
res=method1(i[0])
if res[:2]==i[1]:
print(i[2].format(res[2]))
return
else:
print("No match")
printres([("Hello",(1,2),"This is it {}"),("World",(3,4),"This is it, second {}"),("The",(4,5),"This is it, third {}")])
Related
Here is my python code:
class Solution():
def isPalindrome(self):
return str(self.x) == str(self.x)[::-1]
s1 = Solution()
s1.x = 121
s1.isPalindrome()
It checks to see if the input is a palindrome. I want to create a new object that has the x value 121 and when I execute the isPalindrom function, I want it to return either a true or false boolean answer.
Currently when I run this program, nothing gets outputted. I am a bit lost as to where to go from here, would appreciate help.
Just print out the return value of isPalindrome(), because if you have a line with only a return value (this case being a boolean), the compiler won't know what to do with it.
class Solution():
def isPalindrome(self):
return str(self.x) == str(self.x)[::-1]
s1 = Solution()
s1.x = 121
print(s1.isPalindrome())
You're not telling the program to print anything. Try using print to make it reveal the answer.
Along with printing results we can also make class more pythonic.
class Solution:
def __init__(self):
self.input = None
def is_palindrome(self):
if isinstance(self.input, str):
return self.input == self.input[::-1]
print("Error: Expects str input")
return False # or leave blank to return None
s1 = Solution()
print(s1.is_palindrome())
s1.input = "121"
print(s1.is_palindrome())
output
Error: Expects str input
False
True
The main idea here is divide number. let's take number 122. First of all you need store it in a variable, in this case r_num. While loop is used and the last digit of the number is obtained by using the modulus operator %. The last digit 2 is then stored at the one’s place, second last at the ten’s place and so on. The last digit is then removed by truly dividing the number with 10, here we use //. And lastly the reverse of the number is then compared with the integer value stored in the temporary variable tmp if both are equal, the number is a palindrome, otherwise it is not a palindrome.
def ispalindrom(x):
r_num = 0
tmp = x
while tmp > 0:
r_num = (r_num * 10) + tmp % 10
tmp = tmp // 10
if x == r_num:
return True
return False
I'm a bit new to programming, and I'm trying to create a root-approximating code. Namely, I'm doing something similar to Newton's method in calculus. The idea is, I'm going to input in a big value, subtract until I know I've passed the root, and then add a smaller quantity until I've passed the root, and iterate until I'm in some comfortable error region.
Here's some pseudo code:
def approx(a,b,i):
while ((1/2)**i) >= (1/2)**10:
while (another function is true):
modify values, record root = r
while (the same function above is false):
modify values, record root = r
return approx(a,b,i+1)
return(a,b,r)
This does not seem to work in Python, so I was wondering if anyone could point me in the correct direction.
Edit: included my actual code:
from fractions import *
from math import sqrt
from math import fabs
def pweight(c,d):
if d > c:
return pweight(d,c)
else:
return [c+d,c,d]
def eweight(a,b):
if a == b:
return [a]
elif b > a:
return eweight(b,a)
else:
return [b] + eweight(a-b,b)
def weight(a,b,c,d):
if a*b/2 > c*d:
print("No Embedding Exists")
return (False)
else:
return (True, [c+d]+sorted((pweight(c,d) + eweight(a,b))[1:], reverse=True))
def wgt(a,b,c,d):
return ([c+d]+sorted((pweight(c,d) + eweight(a,b))[1:], reverse=True))
def red(a,i,k):
d=a[0]-a[1]-a[2]-a[3]
if any(item < 0 for item in a[1:]):
# print ("No Embedding Exists")
return (False, i)
elif d >= 0:
# print ("Embedding Exists! How many iterations?")
# print(i)
return (True, i)
elif d<0:
a=[a[0]+d,a[1]+d,a[2]+d,a[3]+d]+a[4:]
a=[a[0]]+sorted(a[1:],reverse=True)
k.append(a)
i=i+1
return red(a,i,k)
def works(a,b):
L = sqrt(a/(2*b))
w = weight(1,a,L,L*b)
return w[0] and red(w[1],0,[])
def inf(a,b,i):
while ((1/2)**(i+1)) >= (1/2)**(10)):
while works(a,b):
a = a - (1/2)**i
L = sqrt(a/(2*b))
while not works(a,b):
a = a + (1/2)**(i+1)
L = sqrt(a/(2*b))
return inf(a,b,i+1)
return (a,b,L)
I want to input in "inf(9,1,0)" and have this code return something close to (255/32,1,sqrt(255/64)). The main problem is the "while works(a,b):" and "while not works(a,b):" in the function "inf(a,b,i)." I want the function to alternate between the "while works" and "while not works" until i=9.
Any sort of general idea would be appreciated (namely, how do you do some sort of alternating function within a while loop).
If you want to alternate between them, don't put them each in their own while loops, put
while i < 9:
if works(a, b):
do something
if not works(a, b):
do something else
And whatever you test in your while conditions needs to be something that changes somewhere in the loop. Otherwise you'll get an infinite loop.
I want to use return instead of print statements but when I replace the print statements with return I don't get anything back. I know I'm missing something obvious:
def consecCheck(A):
x = sorted(A)
for i in enumerate(x):
if i[1] == x[0]:
continue
print x[i[0]], x[i[0]-1]
p = x[i[0]] - x[i[0]-1]
print p
if p > 1:
print "non-consecutive"
break
elif x[i[0]] == len(x):
print "consecutive"
if __name__ == "__main__":
consecCheck([1,2,3,5])
-----UPDATE------ HERE IS CORRECTED CODE AFTER TAKING HEATH3N's answer:
def consecCheck(A):
x = sorted(A)
for i in enumerate(x):
if i[1] == x[0]:
continue
print x[i[0]], x[i[0]-1]
p = x[i[0]] - x[i[0]-1]
print p
if p > 1:
a = "non-consecutive"
break
elif x[i[0]] == len(x):
a = "consecutive"
return a
if __name__ == "__main__":
print consecCheck([4,3,7,1,5])
I don't think you understand what a return statement does:
A return statement causes execution to leave the current subroutine and resume at the point in the code immediately after where the subroutine was called, known as its return address.
You need to wrap consecCheck([1,2,3,5]) in a print statement. Otherwise, all it does it call the function (which no longer prints anything) and goes back to what it was doing.
print takes python object and outputs a printed representation to console/output window
when return statement used in function execution of program to calling location, also if function execution reaches to return statement then no other line will be executed. read detail difference between print and return
So In your case if you want to show result in output console you may do it as following example:
def my_function():
# your code
return <calculated-value>
val = my_function()
print(val) # so you can store return value of function in `val` and then print it or you can just directly write print(my_function())
In your code you are printing values and continuing execution in that case you might consider using yield keyword suggested by #COLDSPEED or just use print to all statement except last one
I am fairly new to python but worked with recursion previously. I came across this problem while working with recursive functions.
archive = {1: 0}
def engine(base, chain=0):
if base in archive:
return archive[base]
else:
if base == 1:
return chain
elif base % 2 == 0:
get = engine(base/2)
meaning = 1 + get
archive[base] = meaning
else:
next = 3 * base + 1
get = engine(next)
meaning = 1 + get
archive[base] = meaning
print archive(13)
I worked with scheme recently. So, I expected it to work.
I want the code to evaluate till the case bool(base==1) becomes true and then work it's way up ward making a new entry to the dictionary on each level of recursion.
How can I achieve that? I am just counting the level of recursion until the fore-mentioned condition becomes True with the variable 'chain'.
[Solved]: I missed the return statement in two clauses of if-else statement. The scheme would pass the function itself and the last return statement would do the work but not with python. I understand it now.
Thanks everyone who responded. It was helpful.
Your last two elif and else clauses have no return statements and Python returns None by default.
I am trying to write a function which is supposed to compare list structures (the values are indifferent). The problem is that I have two lists which are unequal but the function still returns True even though it actually goes into the else part. I don't understand why and what I did wrong. Here is my code:
def islist(p): #is p a list
return type(p)==type(list())
def ListeIsomorf(a,b):
if len(a)==len(b):
for i,j in zip(a,b):
if islist(i) and islist(j):
ListeIsomorf(i,j)
elif islist(i) or islist(j):
return(False)
return(True)
else:
print(a,"length from the list isn't equal",b)
return(False)
#example lists
ListeE = [[],[],[[]]]
ListeD = [[],[],[[]]]
ListeF = [[[],[],[[]]]]
ListeG = [[],[[]],[[]]]
ListeH = [1,[3]]
ListeI = [1,3]
#tests
print(ListeIsomorf(ListeD,ListeE)) # True
print(ListeIsomorf(ListeD,ListeF)) # False
print(ListeIsomorf(ListeD,ListeG)) # False
print(ListeIsomorf(ListeH,ListeI)) # False
So the problem only occurs with the third print(ListeIsomorf(ListeD,ListeG)) # False. It actually goes into the else part and does print the "length from the list isn't equal" but it doesn't stop and it doesn't give out the return(False). Am I missing something?
The problem is that when your function calls itself recursively:
ListeIsomorf(i,j)
it ignores the returned value.
Thus the comparisons that take place at the second level of recursion have no effect on what the top level returns.
Changing the above to:
if not ListeIsomorf(i,j):
return(False)
fixes the problem.