Convert string to negative number

I need to convert from string type to a number

list = ["-5","4","-3","variable"] # Input
list = [-5,4,-3,"variable"] # epected output

I have a problem when converting the negative number

list[0]=int(list[0])

ValueError: invalid literal for int() with base 10: '-5'

3

5 Answers

Actually, I cannot reproduce your error , it just work in python 2.7.13

>>>int("-5")
>>> -5

and in python 3.4

so, it could be a python version problem , I recommend updating your python version , by reinstalling the newer , from the site , it will replace it perfectly ( packages untouched ) , unless you are using , a special distribution like anaconda ..

for processing your list ( mixed chars and numbers ) use:

try: except: statement.

I encountered this problem in the matplotlib xticklabels Text attribute. The minus signs for negative numbers are encoded as a "minus":

[−] is a minus (Unicode 2212).

Minus: [&minus]; a.k.a. [&#8722]; a.k.a. [&#x2212];

Python seems to code minuses as 'hyphen-minus', Unicode 002D:

[-] is a hyphen-minus (ASCII keyboard, Unicode 002D)

Hyphen minus: [&#45]; a.k.a. [&#x002D];

Here is an example:

>> import matplotlib.pyplot as plt
>> import re
>> x = [0,1,2,3,4,5]
>> y = [0,1,2,1,2,1]
>> fig,ax = plt.subplots(1)
>> plt.plot(x,y)

.

If we try to get at the xticklabels, if we want to manually edit them, we use:

>> l = ax.get_xticklabels()
>> ticks = [i.get_text() for i in l]
>> print(ticks)
['−1', '0', '1', '2', '3', '4', '5', '6']
>> ord(ticks[0])
8722

Try to convert it to an integer:

>> l = ax.get_xticklabels()
>> ticks = [int(i.get_text()) for i in l]
ValueError: invalid literal for int() with base 10: '−1'

This is the same error as in the question, which was difficult for others to recreate. To fix it, use regular expressions:

ticks = [int(re.sub(u"\u2212", "-", i.get_text())) for i in l]
print(ticks)
print(ticks[0] - 1)
[-1, 0, 1, 2, 3, 4, 5, 6]
-2
>> ord(ticks[0])
45

1

I do not know how to replace values in a list, you will have to find that out for yourself. This code here

abc = "abcdefghijklmnopqrstuvwxyz" #to make sure there are no letters in the string
list = ["-5","4","-3","variable"]
def MightWork(list): newlist = [] for item in list: if set(abc) & set(list[item]) = False: newlist.append(int(list[item]))
return newlist
list = MightWork(list)

might work. The reason why your code did not work is because you were changing the entire list into a string, not each individual item in the list. Knowing this, if you have any better solutions, try them.

code you written above is working fine in python3

list1 = ["-5","4","-3","variable"]
list2 = []
print(list1)
for item in list1: try: list2.append(int(item)) except ValueError as e: list2.append(item)
print(list2)

Output

['-5', '4', '-3', 'variable']
[-5, 4, -3, 'variable']

follow this example.

list=[-1,2,'car']
convert=[]
for i in list.split(): if type(i) == str: try: convert.append(type(map(int,i))) except ValueError: convert.append(type(i)) return convert

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