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ValueError: invalid literal for int() with base 10: ''
(15 answers)
Closed last month.
I wrote a program to solve y = a^x and then project it on a graph. The problem is that whenever a < 1 I get the error:
ValueError: invalid literal for int () with base 10.
Any suggestions?
Here's the traceback:
Traceback (most recent call last):
File "C:\Users\kasutaja\Desktop\EksponentfunktsioonTEST - koopia.py", line 13, in <module>
if int(a) < 0:
ValueError: invalid literal for int() with base 10: '0.3'
The problem arises every time I put a number that is smaller than one, but larger than 0. For this example it was 0.3 .
This is my code:
# y = a^x
import time
import math
import sys
import os
import subprocess
import matplotlib.pyplot as plt
print ("y = a^x")
print ("")
a = input ("Enter 'a' ")
print ("")
if int(a) < 0:
print ("'a' is negative, no solution")
elif int(a) == 1:
print ("'a' is equal with 1, no solution")
else:
fig = plt.figure ()
x = [-2,-1.75,-1.5,-1.25,-1,-0.75,-0.5,-0.25,0,0.25,0.5,0.75,1,1.25,1.5,1.75,2]
y = [int(a)**(-2),int(a)**(-1.75),int(a)**(-1.5),int(a)**(-1.25),
int(a)**(-1),int(a)**(-0.75),int(a)**(-0.5),int(a)**(-0.25),
int(a)**(0),int(a)**(0.25),int(a)**(0.5),int(a)**(0.75),
int(a)**1,int(a)**(1.25),int(a)**(1.5),int(a)**(1.75), int(a)**(2)]
ax = fig.add_subplot(1,1,1)
ax.set_title('y = a**x')
ax.plot(x,y)
ax.spines['left'].set_position('zero')
ax.spines['right'].set_color('none')
ax.spines['bottom'].set_position('zero')
ax.spines['top'].set_color('none')
ax.spines['left'].set_smart_bounds(True)
ax.spines['bottom'].set_smart_bounds(True)
ax.xaxis.set_ticks_position('bottom')
ax.yaxis.set_ticks_position('left')
plt.savefig("graph.png")
subprocess.Popen('explorer "C:\\Users\\kasutaja\\desktop\\graph.png"')
def restart_program():
python = sys.executable
os.execl(python, python, * sys.argv)
if __name__ == "__main__":
answer = input("Restart program? ")
if answer.strip() in "YES yes Yes y Y".split():
restart_program()
else:
os.remove("C:\\Users\\kasutaja\\desktop\\graph.png")
Answer:
Your traceback is telling you that int() takes integers, you are trying to give a decimal, so you need to use float():
a = float(a)
This should work as expected:
>>> int(input("Type a number: "))
Type a number: 0.3
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: '0.3'
>>> float(input("Type a number: "))
Type a number: 0.3
0.3
Computers store numbers in a variety of different ways. Python has two main ones. Integers, which store whole numbers (ℤ), and floating point numbers, which store real numbers (ℝ). You need to use the right one based on what you require.
(As a note, Python is pretty good at abstracting this away from you, most other language also have double precision floating point numbers, for instance, but you don't need to worry about that. Since 3.0, Python will also automatically convert integers to floats if you divide them, so it's actually very easy to work with.)
Previous guess at answer before we had the traceback:
Your problem is that whatever you are typing is can't be converted into a number. This could be caused by a lot of things, for example:
>>> int(input("Type a number: "))
Type a number: -1
-1
>>> int(input("Type a number: "))
Type a number: - 1
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: '- 1'
Adding a space between the - and 1 will cause the string not to be parsed correctly into a number. This is, of course, just an example, and you will have to tell us what input you are giving for us to be able to say for sure what the issue is.
Advice on code style:
y = [int(a)**(-2),int(a)**(-1.75),int(a)**(-1.5),int(a)**(-1.25),
int(a)**(-1),int(a)**(-0.75),int(a)**(-0.5),int(a)**(-0.25),
int(a)**(0),int(a)**(0.25),int(a)**(0.5),int(a)**(0.75),
int(a)**1,int(a)**(1.25),int(a)**(1.5),int(a)**(1.75), int(a)**(2)]
This is an example of a really bad coding habit. Where you are copying something again and again something is wrong. Firstly, you use int(a) a ton of times, wherever you do this, you should instead assign the value to a variable, and use that instead, avoiding typing (and forcing the computer to calculate) the value again and again:
a = int(a)
In this example I assign the value back to a, overwriting the old value with the new one we want to use.
y = [a**i for i in x]
This code produces the same result as the monster above, without the masses of writing out the same thing again and again. It's a simple list comprehension. This also means that if you edit x, you don't need to do anything to y, it will naturally update to suit.
Also note that PEP-8, the Python style guide, suggests strongly that you don't leave spaces between an identifier and the brackets when making a function call.
As Lattyware said, there is a difference between Python2 & Python3 that leads to this error:
With Python2, int(str(5/2)) gives you 2.
With Python3, the same gives you: ValueError: invalid literal for int() with base 10: '2.5'
If you need to convert some string that could contain float instead of int, you should always use the following ugly formula:
int(float(myStr))
As float('3.0') and float('3') give you 3.0, but int('3.0') gives you the error.
It might be better to validate a right when it is input.
try:
a = int(input("Enter 'a' "))
except ValueError:
print('PLease input a valid integer')
This either casts a to an int so you can be assured that it is an integer for all later uses or it handles the exception and alerts the user
int() casting can't handle string numbers that have decimal points
- example --> int('13.5') will give you error , but int('13') will convert the
string to integer
Why : This considered as explicit casting required by the user as it prevents you from losing information like 0.5 if you read dataset and don't know it's had floating-point numbers
Work Around >
int(Float("13.5"))
A real-world example I faced: where I wanted the numbers as int while int(I["mpg"]) directly didn't work so I used float() then int()
sum([int(float(i["mpg"])) for i in file])//len(file)
I'm working on lists in Python 3. What am I trying to do is;
I have 2 lists one of them have custom numbers,
other one is empty.
The aim of the code is checking if 1st list's value is bigger than previous value and if it is bigger than previous element, append it to the 2nd list.
I have to use basic pythonic syntax. I cannot use any libraries etc.
list1=[5,9,3,2,7,11]
list2 = []
for i in range(len(list1)):
if list1[i] < list1[i+1]:
list2.append(list1[i+1])
print (list2)
If I run whole block of code I got;
Traceback (most recent call last):
File "<ipython-input-209-8d49a68543e3>", line 4, in <module>
if list1[i] < list1[i+1]:
IndexError: list index out of range
but when I run just list2 I get what am I expecting which is
[9,7,11]
You can't go all the way up to len(list1) - 1 for the value of i and expect i+1 to be an index in the list. list[len(list1)] is outside the list.
If you need i+1 in the loop, the loop can only go till all possible valid values of i+1 which happens to be len(list1) - 2. To get that you need to tweak the range a bit
list1=[5,9,3,2,7,11]
list2 = []
for i in range(len(list1) - 1): # iterate until penultimate index
if list1[i] < list1[i+1]:
list2.append(list1[i+1])
print (list2)
could you use the following instead of ranges? Also uses f strings to print list2
for idx, number in enumerate(list1[:-1]):
if number > list1[idx + 1]:
list2.append(list1[idx + 1])
print(f'{list2 = }')
I am trying to solve this problem where certain numbers are taken and appended into the list.
After that I want to see that the first element is smaller than the next element if yes then remove it from the list.
But during comparison it is throwing this error.
I am new to python and don't know how to resolve this
I've tried to take the input in a different way but still can't solve it.
n=int(input())
l = []
m=input().split()
l.append(m)
print(m)
for i in m:
j=i+1
if i<j:
m.remove(i)
print(m)
It is showing the given error:
Traceback (most recent call last):
File "main.py", line 7, in <module>
j=i+1
TypeError: Can't convert 'int' object to str implicitly
Without knowing your input, I can tell you that the elements of m are strings. The return type of input() is a string and you've created a list of strings in m. You can do j = int(i) + 1 to make that line of code work, but you'll have a lot more work to do to solve your overall problem. i<j will always evaluate to True given the above line.
m = input().split() returns an iterable of strings, split by whitespace. If these are supposed to be integers, you've got to cast it to an integer. Do:
n=int(input())
l = []
m=input().split()
l.append(m)
print(m)
for i in m:
j=int(i)+1 # i is cast to an integer
if i<j:
m.remove(i)
print(m)
so, the question says, we have to sort an array using insertion sort algorithm and print the resulting array after each iteration with numbers separated by space.
please help me understand what is the problem. why it is throwing an error?
input: 1 4 3 5 6 2
def insertionSort2(n, arr):
for i in range(1,n):
small=int(arr[i])
j=i-1
while j>=0 and int(arr[j])>small:
arr[j+1]=arr[j]
j-=1
arr[j+1]=small
print(' '.join(arr))
print('\r')
if __name__ == '__main__':
n = int(input())
arr = input().rstrip().split()
print(' '.join(arr))
insertionSort2(n, arr)
when I printed array in the main function, then the output was:1 4 3 5 6 2
but, when I was trying to print the array in the function insertionSort2
run time error occured.
File "Solution.py", line 30, in <module>
insertionSort2(n, arr)
File "Solution.py", line 19, in insertionSort2
print(' '.join(arr))
TypeError: sequence item 1: expected str instance, int found
The arr is a list of strings at the start of insertionSort. You then take an element and convert it to an int in line 3: small=int(arr[i]).
So small is now an integer and then it assigned into the list arr[j+1]=small.
Which now means that arr contains a mix of strings and integers. The join method is expecting all strings.
I am trying to write a function that takes two integer inputs a and b and returns a random integer on the interval [a,b]. I tried...
from random import randint
a = input("a = ")
b = input("b = ")
print(randint(a,b))
... but I got the following error.
Traceback (most recent call last):
File "/Users/malcolmjonesnz/PycharmProjects/exploratorySurgery/randomIntegerGeneraterOnA,B.py", line 8, in <module>
print(randint(a,b))
File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/random.py", line 218, in randint
return self.randrange(a, b+1)
TypeError: Can't convert 'int' object to str implicitly
I have played around trying to "explicitly" convert the inputs to strings, but I've just worked myself into a state of confusion because I'm such a beginner.
Any help would be much appreciated!
The program works well for me. Please replace input by values you define in the program, such as a=1 and b = 5.
What version of python are you using? Maybe your print command causes some errors, since the error seems to come from this line?