python - 如何从 .t​​xt 文件中提取浮点值以用于 python 中的计算？

Question

count = 0
fname = input("Enter file name: ")
fh = open(fname)
for line in fh:
    if line.startswith("X-DSPAM-Confidence:") :
        print(line)
        count = count + 1
print(count)

有一个包含 27 行的文件，例如 X-DSPAM-Confidence : 0.xxxxx，我需要从它们中提取数值以用于计算。

Answer 1

尝试使用split(':')：

代码：

count = 0
fname = input("Enter file name: ")
fh = open(fname)
for line in fh:
    if line.startswith("X-DSPAM-Confidence:") :
        print(line)
        value = line.split(':')[-1]  # will split line into 'X-DSPAM-Confidence' and 'value'
        # if you have ',' at the end of the line, simply do this:
        value = value.strip(',')
        value = float(value)
        print(value)
        count = count + 1
print(count)

Answer 2

只要格式与您描述的完全一样，您就可以使用以下代码：

float(line.split(':')[1])

如果文本中的变化比您描述的更多，您可能需要尝试正则表达式。

Answer 3

您可以使用str.rfind(':')获取位置，:然后执行字符串切片来获取值。

count = 0
fname = input("Enter file name: ")
fh = open(fname)
for line in fh:
    if line.startswith("X-DSPAM-Confidence:") :
        print(line)
        value = line[line.rfind(':'):]  # will take the last occurrence of : to slice the line
        print(value)
        count = count + 1
print(count)

Answer 4

fname = input("Enter file name:")
fh = open(fname)
count = 0
s=0
for line in fh:
    if not line.startswith("X-DSPAM-Confidence:"):
        continue
    count = count+1
    pos = line.find('0')
    floatingP = float(line[pos:])
    s += floatingP
print(s/count)

Answer 5

fname = input("Enter file name: ")
fh = open(fname)
val = 0
count = 0
for line in fh:
    if line.startswith("X-DSPAM-Confidence:") :
        count = count + 1
        val=val + float(line[line.find('0'):])
    elif not line.startswith("X-DSPAM-Confidence:") :
        continue
print("Average spam confidence:",val/count)

Answer 6

fname = input("Enter file name: ")
fh = open(fname)
count = 0
pos = 0
ans = None
total = 0
for line in fh:
    if not line.startswith("X-DSPAM-Confidence:") : 
        continue
    else :
        count = count + 1
        pos = line.find(':')
        ans = line[pos+1 : ]
        total = total + float(ans)
avg = total/count