Develop Reference

User Input Slice String

stringinput = (str(input("Enter a word to start: ")))
removeinput = (str(input("How many character's do you want to remove?")))
if (str)(removeinput) > (str)(stringinput):
print("Cannot remove more chars than there are chars, try again")
else:
removed = stringinput[-1,-removeinput,1]
print((str)(removed))
Traceback (most recent call last):
File "C:\Users\x\PycharmProjects\pythonProject\Pynative Beginner Tasks.py", line 110, in <module>
removed = stringinput[-1,-removeinput,1]
TypeError: bad operand type for unary -: 'str'
I am doing an exercise to create an input that slices a string.
I understand that removeinput needs to be converted to a string to be part of the slice but I don't know how to convert it in the else statement.
I also need it to be a string to make a comparison incase the user inputs a number greater than the amount of chars in stringinput

It looks like you might be trying to take a slice from anywhere in the string, in which case you would need to get an input for the starting index and an ending index. In the example below I wrote it to remove the number of characters from the end of the string so if you input "hello" and "2" you are left with "hel". This behavior could be modified using the tutorial I have attached below.
Here's a modified version of your code with comments to explain the changes:
stringinput = input("Enter a word to start: ")
removeinput = int(input("How many character's do you want to remove? ")) // the int() function converts the input (a string) into an integer
if removeinput > len(stringinput):
print("Cannot remove more chars than there are chars, try again")
else:
removed = stringinput[:-removeinput] // remove the last characters based on the input
print(removed)
In your code you use (str)(removeinput) and (str)(stringinput). It looks like you are trying to cast the variables as strings, but this is not necessary as both of them are already strings by default. In the modified code I converted the input into an integer using int(). This is because your input is not an integer, it is the string version of the integer. By using int(), we are comparing the integer version of the input.
To address the error that you were getting, the syntax that you are using is not correct. Strings are indexed using colons in Python, not commas. Here is a tutorial that might help you: https://www.digitalocean.com/community/tutorials/how-to-index-and-slice-strings-in-python-3
I hope this helps!

ValueError while inserting into mysql: invalid literal for int() with base 10-error while iterating a list of strings [duplicate]

I got this error from my code:
ValueError: invalid literal for int() with base 10: ''.
What does it mean? Why does it occur, and how can I fix it?

The error message means that the string provided to int could not be parsed as an integer. The part at the end, after the :, shows the string that was provided.
In the case described in the question, the input was an empty string, written as ''.
Here is another example - a string that represents a floating-point value cannot be converted directly with int:
>>> int('55063.000000')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: '55063.000000'
Instead, convert to float first:
>>> int(float('55063.000000'))
55063
See：https://www.geeksforgeeks.org/python-int-function/

The following work fine in Python:
>>> int('5') # passing the string representation of an integer to `int`
5
>>> float('5.0') # passing the string representation of a float to `float`
5.0
>>> float('5') # passing the string representation of an integer to `float`
5.0
>>> int(5.0) # passing a float to `int`
5
>>> float(5) # passing an integer to `float`
5.0
However, passing the string representation of a float, or any other string that does not represent an integer (including, for example, an empty string like '') will cause a ValueError:
>>> int('')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: ''
>>> int('5.0')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: '5.0'
To convert the string representation of a floating-point number to integer, it will work to convert to a float first, then to an integer (as explained in #katyhuff's comment on the question):
>>> int(float('5.0'))
5

int cannot convert an empty string to an integer. If the input string could be empty, consider either checking for this case:
if data:
as_int = int(data)
else:
# do something else
or using exception handling:
try:
as_int = int(data)
except ValueError:
# do something else

Python will convert the number to a float. Simply calling float first then converting that to an int will work:
output = int(float(input))

This error occurs when trying to convert an empty string to an integer:
>>> int(5)
5
>>> int('5')
5
>>> int('')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: ''

The reason is that you are getting an empty string or a string as an argument into int. Check if it is empty or it contains alpha characters. If it contains characters, then simply ignore that part.

Given floatInString = '5.0', that value can be converted to int like so:
floatInInt = int(float(floatInString))

You've got a problem with this line:
while file_to_read != " ":
This does not find an empty string. It finds a string consisting of one space. Presumably this is not what you are looking for.
Listen to everyone else's advice. This is not very idiomatic python code, and would be much clearer if you iterate over the file directly, but I think this problem is worth noting as well.

My simple workaround to this problem was wrap my code in an if statement, taking advantage of the fact that an empty string is not "truthy":
Given either of these two inputs:
input_string = "" # works with an empty string
input_string = "25" # or a number inside a string
You can safely handle a blank string using this check:
if input_string:
number = int(input_string)
else:
number = None # (or number = 0 if you prefer)
print(number)

I recently came across a case where none of these answers worked. I encountered CSV data where there were null bytes mixed in with the data, and those null bytes did not get stripped. So, my numeric string, after stripping, consisted of bytes like this:
\x00\x31\x00\x0d\x00
To counter this, I did:
countStr = fields[3].replace('\x00', '').strip()
count = int(countStr)
...where fields is a list of csv values resulting from splitting the line.

This could also happen when you have to map space separated integers to a list but you enter the integers line by line using the .input().
Like for example I was solving this problem on HackerRank Bon-Appetit, and the got the following error while compiling
So instead of giving input to the program line by line try to map the space separated integers into a list using the map() method.

your answer is throwing errors because of this line
readings = int(readings)
Here you are trying to convert a string into int type which is not base-10. you can convert a string into int only if it is base-10 otherwise it will throw ValueError, stating invalid literal for int() with base 10.

This seems like readings is sometimes an empty string and obviously an error crops up.
You can add an extra check to your while loop before the int(readings) command like:
while readings != 0 or readings != '':
readings = int(readings)

I am creating a program that reads a
file and if the first line of the file
is not blank, it reads the next four
lines. Calculations are performed on
those lines and then the next line is
read.
Something like this should work:
for line in infile:
next_lines = []
if line.strip():
for i in xrange(4):
try:
next_lines.append(infile.next())
except StopIteration:
break
# Do your calculation with "4 lines" here

Another answer in case all of the above solutions are not working for you.
My original error was similar to OP: ValueError: invalid literal for int() with base 10: '52,002'
I then tried the accepted answer and got this error: ValueError: could not convert string to float: '52,002' --this was when I tried the int(float(variable_name))
My solution is to convert the string to a float and leave it there. I just needed to check to see if the string was a numeric value so I can handle it correctly.
try:
float(variable_name)
except ValueError:
print("The value you entered was not a number, please enter a different number")

Replace a number with a word

Given a string. Replace in this string all the numbers 1 by the word one.
Example input:
1+1=2
wished output:
one+one=2
I tried the following but does not work with an int:
s=input()
print(s.replace(1,"one"))
How can I replace an integer?

You got a TypeError like below.
Use '1' of type str as first argument (string instead number) because you want to work with strings and replace parts of the string s.
Try in Python console like:
>>> s = '1+1=2'
>>> print(s.replace(1,"one"))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: replace() argument 1 must be str, not int
>>> print(s.replace('1',"one"))
one+one=2
or simply use the string-conversion method str():
s.replace(str(1), 'one')

Whilst you could simply use a replace(), I would suggest instead using a python dictionary. Defining each number to a word, that would then switch. Like this.
conversion = {
1: 'one',
2: 'two'
}
You can then use this like a dictionary
print(conversion[1]) # "one"
print(conversion[2]) # "two"
This simply makes your code more adaptable, in case you want to convert some numbers and not all. Just an alternative option to consider.

ValueError: invalid literal for int() with base 10: '"1"'

I'm attempting to create a bar chart using a csv file and I keep getting this message.
My data is almost all integers.
for item in text_list :
pieces_list = item.strip().split(',')
print(pieces_list)
Month_list.append(pieces_list[0])
Total_list.append(int(pieces_list[1]))

The string '"1"' is three separate characters: { ", 1, " }, and " is not valid in the context of evaluating an integer. This is no doubt caused by the CSV allowing quotes around a field:
"has quotes", does not have quotes, "1"
You need to strip off those double-quotes from the beginning and end of the string first (if they're there). For example:
>>> withq = '"42"'
>>> int(withq)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: '"42"'
>>> int(withq.strip('"'))
42
Just keep in mind that this will strip all " characters from the start and end of a string, so """"""""42""" will still come through as 42. And replace() will replace quotes anywhere in the string. To be absolutely safe, a better option would probably be a function to do the grunt work for you:
# Get integer from a string CSV field.
# If first and last characters are both '"', convert the inner bit.
# Otherwise, convert the whole thing.
# May throw if bit being converted in not valid integer.
def csv_int(field):
if len(field) >= 2 and field[0] == '"' and field[-1] == '"':
return int(field[1:-1])
return int(field)

Looks like I get the same error when doing
print(int('"1"'))
Notice the " surrounding the digit 1.
ValueError: invalid literal for int() with base 10: '"1"'
So I suggest you use replace() on this string or something else to remove this occurrence.
print(int('"1"'.replace('"','')))
output
1

Convert string to integer in python

def handle_client_move(req):
strmove = req.decode('utf-8')
strmove = strmove[-1:]
sendmove = strmove.strip()
print(int(sendmove))
strmove = '--' + strmove
return(strmove)
I get this errror :
ValueError: invalid literal for int() with base 10: ''
cant convert strmove to integer.

To handle this specific problem, where you're trying to convert an empty string to an integer, you could do this:
int(strmove or 0)
When strmove is the empty string, which is falsey, strmove or 0 evaluates to 0 and that works fine as an argument to int(). You could also use some other number if that's more appropriate.

strmove[-1:] will give you only last symbol in your string. If it is whitespace then strmove.strip() will return empty string. Your error
ValueError: invalid literal for int() with base 10: ''
says that '' (empty string) is invalid literal for integer (which is true).
So depending on what you want, you probably need to strip() before strmove[-1:], or something else.