验证 Python 中 txt 文件 (tsv) 的前 3 行

Question

I have been trying to build a validation rule for txt files that get uploaded to my environment. The files are tab separated and I need to validate the first 3 rows that are in a format such as:

## This Text Here 
## This Text Here
## This Text Here

I need to build a pass fail validation. I have tried doing this with the inbuilt csv function in python with no luck so far. Would appreciate any advice on the best route to go.

Answer 1

Try this:

### it depends on how you open the file but...
# open using with..
with open("test.tsv") as inData:
    # split lines on tabs...
    allLines = [l.split("\t") for l in inData]
    # get the lines in question:
    testLines = [l[0] for l in allLines[:3]]
    # then you could use assert
    for l in testLines:
        assert(l.startswith("##"))
        # and whatever other validation you need for the string
    ### you could ad try/except
    try:
        for l in testLines:
            assert(l.startswith("##"))
    except AssertionError as e:
        print(e, "please use a validated file!")

Further reading: https://www.tutorialspoint.com/python/python_exceptions.htm

Answer 2

Maybe you should give a try pandas:

import pandas as pd

file_name = # your file name
csv = pd.read_csv(file_name, sep='\t')

# do your stuff

Documentation: https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.read_csv.html