Printing specific lines from a text file

I do not know what your problem is all about (would it be a college exercise?), but if you're trying to build an agenda or something, I'd suggest using a more appropriate and easy-to-handle storage format. / p>

  

If it's something more amateur, using same text file storage,   I would suggest using a JSON , an XML or a YAML . Everyone has   packages in Python. If it's something more professional, maybe it's   best to use a database ( MySQL , for example, which also has   packages ready in Python).

In any case, there are several options to do what you want. To facilitate, I suggest using the datetime package to identify the dates. But for this you need to set the location in Portuguese before and, very importantly, use the name of the day of the week correctly ("Monday" instead of "Monday"). p>

The following code reads line by line, testing each line to see if it finds a date (it uses the datetime.strptime function, which throws an exception if it is not a valid date - when I consider it as content from the previously recognized date , stored in the date variable). If it's a date, it opens a new "key" in the info dictionary based on that date. If it is not, it considers it as a content of that entry in your calendar, and simply accumulates it in the current key (when doing info[date] += line + '\n' ).

Note that "logic" is essentially:

You can implement this logic anyway, and the cat's jump is just in step 2 (check if it's a date). This code only tries to facilitate this identification using the locale and datetime packages. But nothing prevents you from using regular expressions or even manual comparison.

Here is the code:

import sys
import locale
from datetime import datetime

# Define a localização para Português do Brasil
locale.setlocale(locale.LC_ALL, 'ptg_bra') # No Windows!
# Em outro OS provavelmente será:
# locale.setlocale(locale.LC_ALL, 'pt_BR')

date = ''
info = {}
with open('teste.txt', 'r') as f:
    for line in f.readlines():

        line = line.strip('\n ') # Remove quebras de linhas e espaços

        # Tenta converter a linha atual para uma data (no formato esperado!)
        # Se sucesso, abre uma nova "chave" de conteúdo
        try:
            key = datetime.strptime(line, '%d %B %Y- %A')
            date = key
            info[date] = ''

        # Se falhou, o conteúdo pertence à chave atual (se há uma)
        except ValueError:
            if date != '':
                info[date] += line + '\n'


date = input('Digite a data para consulta:')
try:
    date = datetime.strptime(date, '%d %B %Y- %A')
except ValueError:
    print('O valor [{}] não é uma data válida.'.format(date))
    sys.exit(-1)

print(info[date])

Remembering that the entry has to be (with "Monday ** - fair **" rather than just "Monday"):

4 Março 2017- Sábado

    meu aniversario

    -prova de calculo



    6 Março 2017- Segunda-feira

    aniversario do Salomao

    - fazer compras

[. . .]

The output of the code is this:

>teste
Digite a data para consulta:6 Março 2017- Segunda-feira

aniversario do Salomao

- fazer compras

  

Q.: Note that the date format is set to dia Mês ano- Dia_da_semana based on %d %B %Y- %A format. If you need   change the format (even adding or removing a space!),   you need to change the format! The list of formats can be consulted   in the documentation or in this quick guide .

Logic

The logic implemented is simple:

Code

  

Removed white space from question content to improve presentation of response, but not necessary for code to work.

# -*- coding: utf-8 -*-

import re

content = """4 Março 2017- Sábado
meu aniversario
-prova de calculo

6 Março 2017- Segunda
aniversario do Salomao
- fazer compras

8 Março 2017- Quarta
feriado
-acordar tarde"""

# Data desejada:
date = "8 Março 2017"

# Localizando todas as datas no arquivo:
dates = re.findall(r"[0-9]{1,2}\s.+\s[0-9]{4}", content)

# Verifica se a data existe no arquivo:
if date not in dates:
    raise Exception("Data não definida")

# Localiza a data desejada no arquivo:
start = content.find(date)

# Verifica o índice da data na lista de datas:
index = dates.index(date)

# Verifica se não é a última data da lista:
if index < len(dates) - 1:

    # Verifica qual é a data posterior à desejada:
    next_date = dates[index + 1]

    # Localiza a próxima data no arquivo:
    end = content.find(next_date)

else:

    # É a última data da lista, então exibe até o final do arquivo:
    end = len(content)

# Exibe o conteúdo:
print(content[start:end])

Outputs

For end , the output is generated:

4 Março 2017- Sábado
meu aniversario
-prova de calculo

For date = "4 Março 2017" , the output is generated:

6 Março 2017- Segunda
aniversario do Salomao
- fazer compras

For date = "6 Março 2017" , the output is generated:

8 Março 2017- Quarta
feriado
-acordar tarde

For date = "8 Março 2017" , the output is generated:

Traceback (most recent call last):
  File "python", line 25, in <module>
Exception: Data não definida

  

See the code working in Repl.it or Ideone .