Develop Reference

How to read content of txt file the values are comma separated and add it to a list?

I have a file that contains the following content. This is a sample of the file. The fine contains up to 1000 values.
'1022409', '10856967', '11665741'
I need to read the file and create this list ['1022409', '10856967', '11665741']
I'm using the following code:
with open('Pafos.txt', 'r') as f:
parcelIds_list = f.readlines()
print (parcelIds_list[0].split(','))
The value is of parcelIds_list parameter is this list ["'1022409', '10856967', '11665741'"] with only index 0.
Any ideas please?

Follow this code
with open ('Pafos.txt', 'r') as f:
# To split
num = f.readline().split(', ')
# To remove ' and create list
# If u want list of string
num_list = [x.replace('\'', '') for x in num]
Output
['1022409', '10856967', '11665741']
If u want list of int
# If u want list of int
num_list = [int(x.replace('\'', '')) for x in num]
Output
[1022409, 10856967, 11665741]
If u have more than one row in file, you need to add some extra line of code

It is a bit hard to code with the few lines you have given from the text file, but try this :
temp = []
with open('Pafos.txt', 'r') as f:
parcelIds_list = f.readlines()
for j in parcelIDS_list:
temp.extend(j.split(", "))
new_list = [i.strip()[1:-1] for i in temp]
print(new_list)
Let me know if this doesn't work, and what went wrong. I will modify my answer likewise.

I found the solution thanks to this.
with open('Pafos.txt', 'r') as f:
parcelIds_list = f.readlines()
cs_mylist = []
for y in [x.split(',') for x in parcelIds_list]:
for z in y:
cs_mylist.append(z.replace(' ', ''))

Probably there is a cleaner way, but this works:
with open('Pafos.txt', 'r') as f:
parcelIds_list = f.readlines()
line = parcelIds_list[0]
line = line.replace("'", "")
line = line.replace(" ", "")
line = line.split(',')
print(line)

python - Store the elements of a string into a list

I have a string with elements one below the other
For Ex:
print res ( where res is the result of a regular expression match )
abc
xyz
But i want to create a list with these elements,
final output: lst = ['abc','xyz']
I tried the below code, but its not working. Any help would be appreciated
lst = []
res = ""
with open(filename, "rt") as myfile:
for line in myfile:
if pattern.search(line) != None:
res = [sub[ : -2] for sub in line.split(' ')[6:len(line)-1]]
print res[0]
for h in res:
print lst.append(h)

Not sure how your original file really looks like but this is the easy way via split() on newlines.
with open(filename, 'r') as f:
s = f.read()
data = s.split('\n')
print(data)

How to make a dictionary entry from each line in a text file?

So, i have this text file which contains this infos:
student_num1 student_name1 student_grade1
student_num2 student_name2 student_grade2
student_num3 student_name3 student_grade3
What i want to do is i want to take each line of this text file as a dictionary entry with this format:
students = { student_num1: [student_name1, student_grade1], student_num2: [student_name2, student_grade2], student_num3: [student_name3, student_grade3] }
Basically, the first string of the line should be the key and the 2 strings next to it would be the value. But i don't know how will i make python separate the strings in each line and assign them as the key and value for the dictionary.
EDIT:
So, i've tried some code: (I saw all your solutions, and i think they'll all definitely work, but i also want to learn to create my solution, so i will really appreciate if you could check mine!)
for line in fh:
line = line.split(";")
student_num = line[0]
student_name = line[1]
student_grade = line[2]
count =+ 1
direc[student_num] = [student_name,student_grade]
student_num = "student_num" + str(count)
student_grade = "student_grade" + str(count)
student_name = "student_name" + str(count)
print(direc)
The problem is i get an error of list index out of range on line 10 or this part "student_name = line[1]"
EDIT: THANK YOU EVERYONE! Every single one of your suggested solutions works! I've also fixed my own solution. This is the fixed one (as suggest by #norok2):
for line in fh:
line = line.split(" ")
student_num = line[0]
student_name = line[1]
student_grade = line[2]
count =+ 1
direc[student_num] = [student_name,student_grade]
student_num = "student_num" + str(count)
student_grade = "student_grade" + str(count)
student_name = "student_name" + str(count)

As a dict comprehension:
with open("data.txt", "r") as f:
students = {k:v for k, *v in map(str.split, f)}
Explanation:
The file object f is already an iterator (that yields each line), we want to split the lines, so we can use map(str.split, f) or (line.split() for line in f).
After that we know, that the first item is the key of the dictionary, and the remaining items are the values. We can use unpacking for that. An unpacking example:
>>> a, *b = [1,2,3]
>>> a
1
>>> b
[2, 3]
Then we use a comprehension to build the dict with the values we are capturing in the unpacking.
A dict comprehension is an expresion to build up dictionaries, for example:
>>> {x:x+1 for x in range(5)}
{0: 1, 1: 2, 2: 3, 3: 4, 4: 5}
Example,
File data.txt:
student_num1 student_name1 student_grade1
student_num2 student_name2 student_grade2
student_num3 student_name3 student_grade3
Reading it
>>> with open("data.txt", "r") as f:
... students = {k:v for k, *v in map(str.split, f)}
...
>>> students
{'student_num1': ['student_name1', 'student_grade1'], 'student_num2': ['student_name2', 'student_grade2'], 'student_num3': ['student_name3', 'student_grade3']}

My current approach uses file handling to open a file in read mode, and then reading the lines present in the file. Then for each line, remove extra new line and whitespaces and split it at space, to create a list. Then used unpacking to store single value as key and a list of 2 values as value. Added values to the dictonary.
temp.txt
student_num1 student_name1 student_grade1
student_num2 student_name2 student_grade2
student_num3 student_name3 student_grade3
main.py
d = dict()
with open("temp.txt", "r") as f:
for line in f.readlines():
key, *values = line.strip().split(" ")
d[key] = values
print(d)
Output
{'student_num1': ['student_name1', 'student_grade1'], 'student_num2': ['student_name2', 'student_grade2'], 'student_num3': ['student_name3', 'student_grade3']}

with open('data.txt') as f:
lines = f.readlines()
d = {}
for line in lines:
tokens = line.split()
d[tokens[0]] = tokens[1:]
print(d)
I hope this is understandable. To split the lines into the different tokens, we use the split1 function.

The reason why your solution is giving you that error is that it seems your lines do not contain the character ;, yet you try to split by that character with line = line.split(";").
You should replace that with:
line = line.split(" ") to split by the space character
or
line = line.split(";") to split by any blank character
However, for a more elegant solution, see here.

Have you tried something as simple as this:
d = {}
with open('students.txt') as f:
for line in f:
key, *rest = line.split()
d[key] = rest
print(d)
# {'student_num1': ['student_name1', 'student_grade1'], 'student_num2': ['student_name2', 'student_grade2'], 'student_num3': ['student_name3', 'student_grade3']}

file.txt:
student_num1 student_name1 student_grade1
student_num2 student_name2 student_grade2
student_num3 student_name3 student_grade3
Main.py:
def main():
file = open('file.txt', 'r')
students = {}
for line in file:
fields = line.split(" ")
fields[2] = fields[2].replace("\n", "")
students[fields[1]] = [fields[0], fields[2]]
print(students)
main()
Output:
{'student_name1': ['student_num1', 'student_grade1'], 'student_name2': ['student_num2', 'student_grade2'], 'student_name3': ['student_num3', 'student_grade3']}

inverting the order of lines in a list

I'm having some difficulty with writing a program in Python. I would like the program to read lines between a set of characters, reverse the order of the lines and then write them into a new file. The input is:
AN10 G17 G21 G90
N20 '2014_12_08_Banding_Test_4
N30 M3 S1B
N40G00X0.000Y0.000Z17.000
N50 G00X0.001Y0.001Z17.000
N60 G01Z0.000F3900.0
N70 G01X0.251
N80 G01X149.999
N90 G01Y0.251
N100 G01X149.749
N110 G01X149.499Z-8.169
N120 G01X148.249Z-8.173
N130 G01X146.999Z-8.183
N140 G01X145.499Z-8.201
...
N3140 G01Y0.501
So far my code is:
with open('Source.nc') as infile, open('Output.nc', 'w') as outfile:
copy = False
strings_A = ("G01Y", ".251")
strings_B = ("G01Y", ".501")
content = infile.readlines()
for lines in content:
lines.splitlines(1)
if all(x in lines for x in strings_A):
copy = True
elif all(x in lines for x in strings_B):
copy = False
elif copy:
outfile.writelines(reversed(lines))
I think I am failing to understand something about the difference between lines and a multi-multiline string. I would really appreciate some help here!
Thanks in advance, Arthur

A string has multiple lines if it contains newline characters \n.
You can think of a file as either one long string that contains newline characters:
s = infile.read()
Or you can treat it like a list of lines:
lines = infile.readlines()
If you have a multiline string you can split it into a list of lines:
lines = s.splitlines(False)
# which is basically a special form of:
lines = s.split('\n')
If you want to process a file line by line all of the following methods are equivalent (in effect if not in efficiency) :
with open(filename, 'r') as f:
s = f.read()
lines = s.splitlines()
for line in lines:
# do something
pass
with open(filename, 'r') as f:
lines = f.readlines()
for line in lines:
# do something
pass
# this last option is the most pythonic one,
# it uses the fact that any file object can be treated as a list of lines
with open(filename, 'r') as f
for line in f:
# do something
pass
EDIT Now the solution of your problem:
with open('Source.nc') as infile, open('Output.nc', 'w') as outfile:
copy = False
strings_A = ("G01Y", ".251")
strings_B = ("G01Y", ".501")
target_lines = []
for line in infile:
if copy and all(x in line for x in strings_B):
outfile.writelines(reversed(target_lines))
break
if copy:
target_lines.append(line)
if all(x in line for x in strings_A):
copy = True
This will copy all lines between a line that matches all(x in line for x in strings_A) and a line that matches all(x in line for x in strings_B) into the outfile in reversed order. The identifying lines are NOT included in the output (I hope that was the intent).
The order of the if clauses is deliberate to achieve that.
Also be aware that the identification tests (all(x in line for x in strings_A)) you use, work as a substring search not a word match, again I don't know if that was your intent.
EDIT2 In response to comment:
with open('Source.nc') as infile, open('Output.nc', 'w') as outfile:
strings_A = ("G01Y", ".251")
strings_B = ("G01Y", ".501")
do_reverse = False
lines_to_reverse = []
for line in infile:
if all(x in line for x in strings_B):
do_reverse = False
outfile.writelines(reversed(lines_to_reverse))
outfile.writeline(line)
continue
if do_reverse:
lines_to_reverse.append(line)
continue
else:
outfile.writeline(line)
if all(x in line for x in strings_A):
do_reverse = True
lines_to_reverse = []

Python Subtract integers in List to return a value

I would like to take a large file like this in Python 2.7:
123 456 GTHGGGTH
223 567 FGRTHSYS
12933 4656832 GJWSOOOSKKSSJ
.....
and I want to read in the file line by line, disregard the third element, and subtract the second element in each line by the first element. Thus line 1 above would return 333.
I have tried this so far:
def deleteLast(list):
NewL = list.pop()
return NewL
f = open(file_name, 'r')
line = f.readline()
while line:
L = line.split()
L2 = deleteLast(L)
L3 = [int(number) for number in L2]
Length = L3[1]-L3[0]
print Length
f.close()
But, when I try this the compiler says:
ValueError: invalid literal for int() with base 10: 'T'
All help is appreciated.

That is because list.pop() is returning the "popped off" item, it doesn't return the list again.
Instead of this deleteLast function you have written, it would be better just to use a slice like this:
L2 = line.split()[0:2]
You are going to run into another problem later because your while loop isn't advancing at all. Consider using a for loop instead.

You can try something like this :
In [8]: with open("abc") as f: #always use with statement when handling files
...: for line in f:
...: x,y=map(int,line.split()[:2])
...: print y-x
...:
333
344
4643899

try the following:
with open(file_name, 'r') as f:
for line in f.readlines():
rowData = line.split()
left, right = map(int, rowData[:2])
length = right - left
print length
Or:
from operator import sub
with open(file_name, 'r') as f:
for line in f.readlines():
print sub(*map(int, line.split()[:2])[::-1])

f = open(file_name, 'r')
for line in f.readlines():
x, y = line.split(' ')[:2]
print int(y) - int(x)