读取文件中未知数量的行

Question

I wrote the code below, but it specifies the number of lines in the file. I'm wondering how I can change it so that it will read an unknown number of lines?

n = int(input("instance: "))
tp, tn, fp, fn = 0
for i in range(n):
    real, predicted = map(int, input().split(' '))
    for num in i:
        if real == 1 and predicted == 1:
            tp += 1
        elif real == 0 and predicted == 0:
            tn += 1
        elif real == 1 and predicted == 0:
            fn += 1
        else:
            fp += 1

pr = tp / (tp + fp)
rc = tp / (tp + fn)
f1 = 2 * ((pr * rc) / (pr + rc))
print("f1= ", f1)

My code reads these lines and compares numbers on each line with each other, but not with numbers on the other lines.

The input looks like this:

1 1
0 0
0 1
0 1
1 0
0 1
0 0
1 1
0 0
0 0
0 0
0 0
1 1

Answer 1

Keep reading until EOFError is thrown:

tp, tn, fp, fn = 0
i = 0
try:
    while True:
        real, predicted = map(int, input().split(' '))
        for num in i:
            if real == 1 and predicted == 1:
                tp += 1
            elif real == 0 and predicted == 0:
                tn += 1
            elif real == 1 and predicted == 0:
                fn += 1
            else:
                fp += 1
        i += 1
except EOFError:
    pass
pr = tp / (tp + fp)
rc = tp / (tp + fn)
f1 = 2 * ((pr * rc) / (pr + rc))
print("f1= ", f1)

Your code has errors too:

• multiple variables can't be assigned to the same value using unpacking.
• range needs to be used if you want to count up to a number.

This should fix them:

tp = tn = fp = fn = 0
i = 0
try:
    while True:
        real, predicted = map(int, input().split(' '))
        for num in range(i):
            if real == 1 and predicted == 1:
                tp += 1
            elif real == 0 and predicted == 0:
                tn += 1
            elif real == 1 and predicted == 0:
                fn += 1
            else:
                fp += 1
        i += 1
except EOFError:
    pass
pr = tp / (tp + fp)
rc = tp / (tp + fn)
f1 = 2 * ((pr * rc) / (pr + rc))
print("f1= ", f1)