python - 从 txt 文件中读取列表中的数字，但最多只能是逗号

Question

这是来自实验室实验的数据(大约 717 行数据)。我不想试图超越它，而是想在 python 或 matlab 上导入并绘制它。顺便说一下，我是新来的...而且是一名学生!

""
"Test Methdo","exp-l Tensile with Extensometer.msm"
"Sample I.D.","Sample108.mss"
"Speciment Number","1"

"Load (lbf)","Time (s)","Crosshead (in)","Extensometer (in)"

62.638,0.900,0.000,0.00008
122.998,1.700,0.001,0.00012

more numbers : see Screenshot of more data from my file

直到出现逗号，我才明白如何阅读整行。具体来说，我需要我的一个数组/列表的加载编号，例如，在第一行我只需要 62.638(这将是我的列表/数组中第一个索引的第一个数字)。

我怎样才能得到这个数组/列表，迭代/读取列表并忽略字符串的东西？

谢谢!

注意:我使用 Anaconda + Jupyter Notebooks for Python 和 Matlab(学校提供的软件)。

编辑:好的，所以我今天回到家并再次处理它。我以前没有处理过 CSV 文件，但经过一些搜索后，我能够学习如何阅读我的文件。

import csv
from itertools import islice

with open('Blue_bar_GroupD.txt','r') as BB:
    BB_csv = csv.reader(BB)
    x = 0
    BB_lb = []
    while x < 7: #to skip the string data
        next(BB_csv)
        x+=1
    for row in islice(BB_csv,0,758):
        print(row[0]) #testing if I can read row data

好的，这就是我被困的地方。我想制作一个每行都有第 0 个索引值的数组/列表。对不起，如果我是个菜鸟!

再次感谢!

Answer 1

您可以跳过所有行直到第一个数据行，然后将数据解析为列表供以后使用——700 多行可以在内存中轻松处理。

为此你需要:

• 逐行读取文件
  • 记住数字/逗号/点之前的最后一个非空行(== header)
  • 查看该行是否只有数字/逗号/点，否则增加一个跳过计数器(==数据)
• 寻找到 0
• 跳过足够多的行以到达标题或数据
• 将其余部分读入数据结构

---

创建测试文件:

text = """
""
"Test Methdo","exp-l Tensile with Extensometer.msm"
"Sample I.D.","Sample108.mss"
"Speciment Number","1"

"Load (lbf)","Time (s)","Crosshead (in)","Extensometer (in)"

62.638,0.900,0.000,0.00008
122.998,1.700,0.001,0.00012
""" 
with open ("t.txt","w") as w:
    w.write(text)

一些助手和跳过/阅读逻辑:

import re
import csv

def convert_row(row):
    """Convert one row of data into a list of mixed ints and others.
    Int is the preferred data type, else string is used - no other tried."""
    d = []
    for v in row:
        try:
            # convert to int && add
            d.append(float(v))
        except: 
            # not an int, append as is
            d.append(v)
    return d

def count_to_first_data(fh):
    """Count lines in fh not consisting of numbers, dots and commas.
    Sideeffect: will reset position in fh to 0."""
    skiplines = 0
    header_line = 0
    fh.seek(0)
    for line in fh:
        if re.match(r"^[\d.,]+$",line):
            fh.seek(0)
            return skiplines, header_line
        else:
            if line.strip():
                header_line = skiplines
            skiplines += 1
    raise ValueError("File does not contain pure number rows!")

助手的使用/数据转换:

data = []
skiplines = 0
with open("t.txt","r") as csvfile:
    skip_to_data, skip_to_header = count_to_first_data(csvfile)

    for _ in range(skip_to_header): # skip_to_data if you do not want the headers
        next(csvfile)
    reader = csv.reader(csvfile, delimiter=',',quotechar='"')
    for row in reader:
        row_data = convert_row(row) 
        if row_data:
            data.append(row_data)

print(data)

输出(重新格式化):

[['Load (lbf)', 'Time (s)', 'Crosshead (in)', 'Extensometer (in)'], 
 [62.638, 0.9, 0.0, 8e-05], 
 [122.998, 1.7, 0.001, 0.00012]]

独库:

• re.match
• csv.reader
• Method of file objekts (i.e.: seek())

---

有了这个，您现在拥有可用于进一步处理的“干净”数据 - 包括您的 header 。

对于可视化，您可以查看 matplotlib