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How to print strings from a text file,separated by new line in Python

I'm new in Python and i'm challenging myself by making an online library management with prompt for the 1st phase.I'm stacked in search function.I have found how to print a user's input,but i can't find how to print and the following data.I want to search a book by name.If book's name is in the text,i want to print the details of the book,like author,isbn etc.
Here is the following code i have made:
def search():
search_book = input('Search a book: ')
with open('library.txt', mode='r', encoding='utf-8') as f:
index = 0
for line in f:
index += 1
if search_book in line:
print(f'{search_book} is in line {index}')
for details in range(index,index+5):
print(line[details])
And this is the text file's data:
FIRST
ME
9781234
2000
Science
SECOND
YOU
9791234
1980
Literature
It is separated by new line.As example a user input the name FIRST and the result will be:
FIRST
ME
9781234
2000
Science

There are two file options we can consider,
Csv file - Instead of individual readline, you could use one line for one book entry.
# ---------test.csv -------------
# BookName, ItemCode, Price
# Book1, 00012, 14.55
# Book2, 00232, 55.12
# -----End Csv-------------------
import csv
def read_csv(filename:str):
file_contents = None
# reading csv file
with open(filename, 'r') as csvfile:
file_contents = csv.reader(csvfile)
return file_contents
def search(file_contents, book_name:str):
if not file_contents:
return None
for line in file_contents:
if book_name in line:
return line
if __name__ == '__main__':
file_contents = read_csv('test.csv')
line = search(file_contents, 'ME')
print(line if line else 'No Hit Found')
Json - This is much better option than csv file
import json
def read_json(filename:str) -> dict:
with open(filename) as json_file:
all_books = json.load(json_file)
return all_books
def search(all_books:dict, book_name:str):
for book_id, book_details in all_books.items():
if book_details['Name'] == book_name:
return book_details
return None
if __name__ == '__main__':
all_books = read_json('books.json')
book = search(all_books, 'YOU')
print(book if book else 'Not hit found')
If your file contents can't change, then I will go with #tripleee suggestion above. Good luck.

You are reading a line at a time, and looping over the first line's contents. At this point in the program, there are not yet any additional lines. But a fix is relatively easy:
def search():
search_book = input('Search a book: ')
with open('library.txt', mode='r', encoding='utf-8') as f:
index = 0
print_this_many = 0
for line in f:
index += 1
if search_book in line:
print(f'{search_book} is in line {index}')
print_this_many = 5
if print_this_many:
print(line, end='')
print_this_many -= 1
We don't have the next lines in memory yet, but we can remember how many of them to print as we go ahead and read more of them. The print_this_many variable is used for this: When we see the title we want, we set it to 5 (to specify that this and the next four lines should be printed). Now, each time we read a new line, we check if this variable is positive; if it is, we print the line and decrement the variable. When it reaches zero, we will no longer print the following lines. This allows us to "remember" across iterations of the for loop which reads each new line whether we are in the middle of printing something.
A much better solution is to read the database into memory once, and organize the lines into a dictionary, for example.
def read_lib(filename):
library = dict()
with open(filename) as lib:
title = None
info = []
for line in lib:
line = line.rstrip('\n')
if title is None:
title = line
elif line == '':
if title and info:
library[title] = info
title = None
else:
info.append(line)
def search(title, library):
if title in library:
return library[title]
else:
return None
def main():
my_library = read_lib('library.txt')
while True:
sought = input('Search a book: ')
found = search(sought, my_library)
if found:
print('\n'.join(found))
else:
print('Sorry, no such title in library')

Try statement not running as I expect

I have three functions, the readHeader thet reads the header of the a txt file, readExpertsFile that reads the contents of the file and the exceptionNH function that compares the file name and header and raises an exception if the two are not compatible (e.g. if the date in the name is not the same as the header).
Here are the three functions and a txt example:
def readHeader(fileName):
fileIn = open(fileName, "r")
fileIn.readline()
day = fileIn.readline().replace("\n", "")
fileIn.readline()
time = fileIn.readline().replace("\n", "")
fileIn.readline()
company = fileIn.readline().replace("\n", "")
scope = fileIn.readline().replace(":", "").replace("\n", "")
fileIn.close()
return (day, time, company, scope)
def readFile(fileName):
expertsList = []
expertsList.append(readHeader(fileName))
fileIn = open(fileName, "r")
for line_counter in range(LNHEADER):
fileIn.readline()
fileInE.close()
return expertsList
def exceptionNH(fileName):
try:
assert fileName[10:17] == readFile(fileName)[3][0].lower().replace(":", "")
except AssertionError:
print("Error in input file: inconsistent name and header in file", fileName,".")
exit()
fileName = "file.txt"
exceptionNH("2018y03m28experts10h30.txt")
2018y03m28experts10h30.txt:
Day:
2018-03-28
Time:
10:30
Company:
XXX
Experts:
...
...
My problem here is that on the try statement I expect the assert "sees" the comparation as True and skip the except clause but this is not happening.
I suspect that the .lower() is not working but I can't understand why.
If you see other things that could be better feel free to share, as I'm a new at python and want to improve myself.

I've found the error. I was thinking that when I want to get the first element from the first tuple inside a list, I would need to write list[position of item][position of tuple], instead of it's inverse.
Following the mkrieger1's advice, I printed fileName[10:17] and readFile(fileName)[3][0].lower().replace(":", ""), the first was good but the second was not showing the third item of the first tuple (that's from readHeader) but the first item of the third tuple.
I've changed from readFile(fileName)[3][0].lower().replace(":", "") to readFile(fileName)[0][3].lower().replace(":", "") and it's working now, thank you for the help.

How to pass dictionary to functions?

I want to pass dictionary to user defined functions and I need to do some calculation based on the dictionary values. It is not working for me with functions but works fine without using functions. I am not sure, what is wrong with code. Any help please? No error message.
Input:
"13-07-2016 12:55:46",user,192.168.10.100,192.168.10.20,CONNECT,200,"www.abc.com"
"13-07-2016 12:57:50",user,192.168.10.100,192.168.10.20,CONNECT,200,"www.abc.com"
"13-07-2016 13:00:43",user,192.168.10.100,192.168.10.20,CONNECT,200,"www.abc.com"
"13-07-2016 13:01:45",user,192.168.10.100,192.168.10.20,CONNECT,200,"www.abc.com"
"13-07-2016 13:02:57",user,192.168.10.100,192.168.10.20,CONNECT,200,"www.abc.com"
"13-07-2016 13:04:59",user,192.168.10.100,192.168.10.20,CONNECT,200,"www.abc.com"
"13-07-2016 13:06:51",user,192.168.10.100,192.168.10.20,CONNECT,200,"www.abc.com"
"13-07-2016 13:07:56",user,192.168.10.100,192.168.10.20,CONNECT,200,"www.abc.com"
Code:
file_name = sys.argv[1]
fo = open(file_name, "rb")
def setdict():
dico,i={},0
line = fo.readline()
for line in fo:
date, user, proxy_ip, client_ip, access_method, con, sites = line.split(",")
sites = sites.rstrip('\n')
dico[i]= date, user, proxy_ip, client_ip, access_method, con, sites
return dico
def display(dico):
for k,v in dico.items():
print k,v

A: You should consider to call your functions at the end of the script:
dico = setdict()
display(dico)
Without that, they are declared, but not used.
B: You should also consider a better way to open your file:
with open(file_name, "rb") as f:
lines = f.readlines()
for line in lines:
# Do stuff with your line
This is the best way to open a file in python and to read it line by line.
C: You are using:
line = fo.readline()
# ^ That line is never use after, you will loose all it's datas
for line in fo:
#do stuff on line
I've add a comment to show you that you loose the data from the first line.
D: You are using global variable (you use fo inside setdict() a better way will be to pass it by arguments:
fo = open(file_name, "rb")
def setdict(fo):
dico,i={},0
line = fo.readline()
...
setdict(fo)
Finally, here is how you can rewrite your script :
def setdict(filename):
dico,i={},0
with open(filename, 'r') as f:
for line in f.readlines():
date, user, proxy_ip, client_ip, access_method, con, sites = line.split(",")
sites = sites.rstrip('\n')
dico[i]= date, user, proxy_ip, client_ip, access_method, con, sites
return dico
def display(dico):
for k,v in dico.items():
print k,v
file_name = sys.argv[1]
dico = setdict(filename)
display(dico)

When you write a function in Python using the def keyword, the function is not automatically executed. You are never calling your setdict or display functions, just defining them so they can be called later.
Add this line to the end of your script to actually call the functions you defined:
display(setdict())
or more verbosely
dico = setdict()
display(dico)

How can I parse a formatted file into variables using Python?

I have a pre-formatted text file with some variables in it, like this:
header one
name = "this is my name"
last_name = "this is my last name"
addr = "somewhere"
addr_no = 35
header
header two
first_var = 1.002E-3
second_var = -2.002E-8
header
As you can see, each score starts with the string header followed by the name of the scope (one, two, etc.).
I can't figure out how to programmatically parse those options using Python so that they would be accesible to my script in this manner:
one.name = "this is my name"
one.last_name = "this is my last name"
two.first_var = 1.002E-3
Can anyone point me to a tutorial or a library or to a specific part of the docs that would help me achieve my goal?

I'd parse that with a generator, yielding sections as you parse the file. ast.literal_eval() takes care of interpreting the value as a Python literal:
import ast
def load_sections(filename):
with open(filename, 'r') as infile:
for line in infile:
if not line.startswith('header'):
continue # skip to the next line until we find a header
sectionname = line.split(None, 1)[-1].strip()
section = {}
for line in infile:
if line.startswith('header'):
break # end of section
line = line.strip()
key, value = line.split(' = ', 1)
section[key] = ast.literal_eval(value)
yield sectionname, section
Loop over the above function to receive (name, section_dict) tuples:
for name, section in load_sections(somefilename):
print name, section
For your sample input data, that results in:
>>> for name, section in load_sections('/tmp/example'):
... print name, section
...
one {'last_name': 'this is my last name', 'name': 'this is my name', 'addr_no': 35, 'addr': 'somewhere'}
two {'first_var': 0.001002, 'second_var': -2.002e-08}

Martijn Pieters is correct in his answer given your preformatted file, but if you can format the file in a different way in the first place, you will avoid a lot of potential bugs. If I were you, I would look into getting the file formatted as JSON (or XML), because then you would be able to use python's json (or XML) libraries to do the work for you. http://docs.python.org/2/library/json.html . Unless you're working with really bad legacy code or a system that you don't have access to, you should be able to go into the code that spits out the file in the first place and make it give you a better file.

def get_section(f):
section=[]
for line in f:
section += [ line.strip("\n ") ]
if section[-1] == 'header': break
return section
sections = dict()
with open('input') as f:
while True:
section = get_section(f)
if not section: break
section_dict = dict()
section_dict['sname'] = section[0].split()[1]
for param in section[1:-2]:
k,v = [ x.strip() for x in param.split('=')]
section_dict[k] = v
sections[section_dict['sname']] = section_dict
print sections['one']['name']
You can also access these sections as attributes:
class Section:
def __init__(self, d):
self.__dict__ = d
one = Section(sections['one'])
print one.name

How do I remove a particular line from a file but keep other lines intact?

I want to learn Python so I started writing my first program which is a phone book directory.
It has the options to add a name and phone number, remove numbers, and search for them.
Ive been stuck on the remove part for about 2 days now and just can't get it working correctly. I've been in the Python IRC and everything, but haven't been able to figure it out.
Basically, my program stores the numbers to a list in a file. I cannot figure out how to remove a particular line in the file but keep the rest of the file intact. Can someone please help me with this?
Some people have advised that it will be easier to do if I create a temp file, remove the line, then copy the remaining lines from the original file over to the temp file. Then write over the original file over with the temp file. So I have been trying this...
if ui == 'remove':
coname = raw_input('What company do you want to remove? ') # company name
f = open('codilist.txt', 'r') # original phone number listing
f1 = open('codilist.tmp', 'a') # open a tmp file
for line in f:
if line.strip() != coname.strip():
for line in f:
f1.write(line)
break # WILL LATER OVERWRITE THE codilist.txt WITH THE TMP FILE
else:
f1.write(line)
else:
print 'Error: That company is not listed.'
f1.close()
f.close()
continue

I assume your file contains something like <name><whitespace><number> on each line? If that's the case, you could use something like this for your if statement (error handling not included!):
name, num = line.strip().split()
if name != coname.strip():
# write to file
Suggestion:
Unless there is some specific reason for you to use a custom format, the file format json is quite good for this kind of task. Also note the use of the 'with' statement in these examples, which saves you having to explicitly close the file.
To write the information:
import json
# Somehow build a dict of {coname: num,...}
info = {'companyA': '0123456789', 'companyB': '0987654321'}
with open('codilist.txt', 'w') as f:
json.dump(info, f, indent=4) # Using indent for prettier files
To read/amend the file:
import json
with open('codilist.txt', 'r+') as f:
info = json.load(f)
# Remove coname
if coname in info:
info.pop(coname)
else:
print 'No record exists for ' + coname
# Add 'companyC'
info['companyC'] = '0112233445'
# Write back to file
json.dump(info, f, indent=4)
You'll need python2.6 or later for these examples. If you're on 2.5, you'll need these imports:
import simplejson as json
from __future__ import with_statement
Hope that helps!

Here is a pretty extensively rewritten version:
all the phone data is wrapped into a Phonebook class; data is kept in memory (instead of being saved and reloaded for every call)
it uses the csv module to load and save data
individual actions are turned into short functions or methods (instead of One Big Block of Code)
commands are abstracted into a function-dispatch dictionary (instead of a cascade of if/then tests)
This should be much easier to understand and maintain.
import csv
def show_help():
print('\n'.join([
"Commands:",
" help shows this screen",
" load [file] loads the phonebook (file name is optional)",
" save [file] saves the phonebook (file name is optional)",
" add {name} {number} adds an entry to the phonebook",
" remove {name} removes an entry from the phonebook",
" search {name} displays matching entries",
" list show all entries",
" quit exits the program"
]))
def getparam(val, prompt):
if val is None:
return raw_input(prompt).strip()
else:
return val
class Phonebook(object):
def __init__(self, fname):
self.fname = fname
self.data = []
self.load()
def load(self, fname=None):
if fname is None:
fname = self.fname
try:
with open(fname, 'rb') as inf:
self.data = list(csv.reader(inf))
print("Phonebook loaded")
except IOError:
print("Couldn't open '{}'".format(fname))
def save(self, fname=None):
if fname is None:
fname = self.fname
with open(fname, 'wb') as outf:
csv.writer(outf).writerows(self.data)
print("Phonebook saved")
def add(self, name=None, number=None):
name = getparam(name, 'Company name? ')
number = getparam(number, 'Company number? ')
self.data.append([name,number])
print("Company added")
def remove(self, name=None):
name = getparam(name, 'Company name? ')
before = len(self.data)
self.data = [d for d in self.data if d[0] != name]
after = len(self.data)
print("Deleted {} entries".format(before-after))
def search(self, name=None):
name = getparam(name, 'Company name? ')
found = 0
for c,n in self.data:
if c.startswith(name):
found += 1
print("{:<20} {:<15}".format(c,n))
print("Found {} entries".format(found))
def list(self):
for c,n in self.data:
print("{:<20} {:<15}".format(c,n))
print("Listed {} entries".format(len(self.data)))
def main():
pb = Phonebook('phonebook.csv')
commands = {
'help': show_help,
'load': pb.load,
'save': pb.save,
'add': pb.add,
'remove': pb.remove,
'search': pb.search,
'list': pb.list
}
goodbyes = set(['quit','bye','exit'])
while True:
# get user input
inp = raw_input("#> ").split()
# if something was typed in
if inp:
# first word entered is the command; anything after that is a parameter
cmd,args = inp[0],inp[1:]
if cmd in goodbyes:
# exit the program (can't be delegated to a function)
print 'Goodbye.'
break
elif cmd in commands:
# "I know how to do this..."
try:
# call the appropriate function, and pass any parameters
commands[cmd](*args)
except TypeError:
print("Wrong number of arguments (type 'help' for commands)")
else:
print("I didn't understand that (type 'help' for commands)")
if __name__=="__main__":
main()

Something simple like this will read all of f, and write out all the lines that don't match:
for line in f:
if line.strip() != coname.strip():
f1.write(line)

Ned's answer looks like it should work. If you haven't tried this already, you can set python's interactive debugger above the line in question. Then you can print out the values of line.strip() and coname.strip() to verify you are comparing apples to apples.
for line in f:
import pdb
pdb.set_trace()
if line.strip() != coname.strip():
f1.write(line)
Here's a list of pdb commands.

You probably don't want to open the temp file in append ('a') mode:
f1 = open('codilist.tmp', 'a') # open a tmp file
also, be aware that
for line in f:
...
f1.write(line)
will write everything to the file without newlines.
The basic structure you want is:
for line in myfile:
if not <line-matches-company>:
tmpfile.write(line + '\n') # or print >>tmpfile, line
you'll have to implement <line-matches-company> (there isn't enough information in the question to know what it should be -- perhaps if you showed a couple of lines from your data file..?)

I got this working...
if ui == 'remove':
coname = raw_input('What company do you want to remove? ') # company name
f = open('codilist.txt')
tmpfile = open('codilist.tmp', 'w')
for line in f:
if coname in line:
print coname + ' has been removed.'
else:
tmpfile.write(line)
f.close()
tmpfile.close()
os.rename('codilist.tmp', 'codilist.txt')
continue