Python：从txt文件中提取浮点数

Question

I have this txt file:

TP 0.8329 

And i tried to extract that float after "TP" using the following code:

def definir_operacao():
    end = 0
    oper = []
    for x in range(len(lines[0])):
        if(lines[0][x] == " "):
            end += 1
        elif(end == 1):
            oper.append(int(lines[0][x]))
    str2 = ''.join(oper)
    return str2


ci = definir_operacao()
print(ci)

But i get a empty variable as response, so i guess i'm making something wrong, can anyone help me?

Answer 1

Just do this one-liner instead:

ci = float(lines[0].split()[1])

And now:

print(ci)

Would give:

0.8329

Answer 2

You're checking that whether you get an " " , and if so you're appending the exact same " " with oper . See this segment again:

if(lines[0][x] == " "):
        end += 1
elif(end == 1):
        oper.append(int(lines[0][x]))

That is why you're getting empty as response.

just split the line on the basis of " " and take the second value from the splitting result. Don't forget to cast it to float. That will give you what you want.

res = float(lines[0].split(" ")[1])
    

You can just use split() too as @U11-Forward mentioned, because default separator is whitespace.