Python：如何从文本文件中拆分位置数据

Question

我有一个文本文件，其中包含我试图用Python读取的数据：

OMEGA2    1.450E+00 1.500E+00 1.550E+00 1.600E+00 1.650E+00 1.700E+00
OMEGA2    1.800E+00 1.850E+00 1.900E+00 1.950E+00 2.000E+00 2.050E+00
F2REAL    1.146E+00 -1.015E+03-2.206E+03-2.618E+03-2.288E+03-1.400E+03
F2REAL    6.255E+00 -3.254E+02-8.150E+02-1.060E+03-9.749E+02-5.995E+02
F2REAL    1.754E+01 -1.530E+02-4.375E+02-5.932E+02-5.618E+02-3.536E+02
F2REAL    1.740E+01 -7.981E+01-2.525E+02-3.748E+02-3.891E+02-2.739E+02
OMEGA2    1.800E+00 1.850E+00 1.900E+00 1.950E+00 2.000E+00 2.050E+00

现在，我只想得到以F2REAL开头的值；每行，我要提取6个值。值1从索引11到索引20，值到从索引21到30。。。，值6来自索引61:70

我尝试了以下方法：

file = 'file.txt'
STR1 = 'F2REAL'

def get_data():
    with open(file) as f:
        hyd_all = f.readlines()
        for line in hyd_all:
            if STR1 in line:
                print([float(line[10:19]),float(line[20:29])])

get_data()

1. 这不会读取电子功率，因为我得到了[1.146,-1.015，...]。我如何正确地得到它？
2. 有没有更好的方法而不是写10:19,20:29,..60:69？所有感兴趣的行都有6列并且总是从10*i开始
3. 我想将每个结果附加到一个矩阵中。在这个4行6列的示例中

Answer 1

def parse_scientific(s):
    root = float(s.split('E')[0])
    exp  = int(s.split('E')[1])
    return root*(10**exp)

def get_data():
    with open(file) as f:
        hyd_all = f.readlines()
        for line in hyd_all:
            if line.startswith(STR1):
                item_values = [parse_scientific(line[offset*10:offset*10+10]) for offset in range(1,7)]

使用item_values插入矩阵

Answer 2

file = 'file.txt'
STR1 = 'F2REAL'

def get_data():
    with open(file) as f:
        hyd_all = f.readlines()
        for line in hyd_all:
            if STR1 in line:
                print(line[10:20],line[20:30],line[30:40],line[40:50],line[50:60],line[60:70])

get_data()

结果如下：

Answer 3

>

你可以用列表理解

假设您正在谈论一个numpy矩阵（否则只需切换到pandas数据帧）：

import numpy as np


def get_data(path: str, target: str, width: int = 10):
    values = []
    with open(path, 'r') as f:
        for line in f.readlines():
            # 'F2REAL' should be at the beginning of the line not just anywhere
            if line.startswith(target):
                # map sequential fixed widths to float
                values.append([float(line[width*i:width*(i+1)]) for i in range(1, 7)])

    return np.asarray(values)
    

print(get_data('file.txt', 'F2REAL'))

输出：

[[ 1.146e+00 -1.015e+03 -2.206e+03 -2.618e+03 -2.288e+03 -1.400e+03]
 [ 6.255e+00 -3.254e+02 -8.150e+02 -1.060e+03 -9.749e+02 -5.995e+02]
 [ 1.754e+01 -1.530e+02 -4.375e+02 -5.932e+02 -5.618e+02 -3.536e+02]
 [ 1.740e+01 -7.981e+01 -2.525e+02 -3.748e+02 -3.891e+02 -2.739e+02]]