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write items from a list to a text file in different line

I'm trying to get user inputs a few times and then save those inputs to a list and after that write list items to a text file.
the list would look like this with the inputs.
prog_input = [120,0,0,100,20,0,100,0,20]
I wrote this to a text file using:
txtfile1 = open("Input progression data.txt", "w+")
txtfile1.write(', '.join([str(item) for item in prog_input])+ '\n')
This just print them in a line.()
The output I'm trying to get is(in the text file):
120,0,0
100,20,0
100,0,20

prog_input is just a flattened list, so you need to group your items into chunks and then output to your file
prog_input = [120, 0, 0, 100, 20, 0, 100, 0, 20]
step = 3
with open("Input progression data.txt", "w+") as myfile:
for chunk in [prog_input[n:n+step] for n in range(0, len(prog_input), step)]:
myfile.write(','.join(map(str, chunk)) + '\n')

You can use numpy.array_split to split your list into sub-lists of size 3 each:
import numpy as np
prog_input = [120,0,0,100,20,0,100,0,20]
with open("Input progression data.txt", "w") as outfile:
outfile.write("\n".join([", ".join(map(str, chunk)) for chunk in np.array_split(prog_input, 3)]))

Looks like you want 3 values per line. So...
F = "Input progression data.txt"
prog_input = [120,0,0,100,20,0,100,0,20]
with open(F, 'w') as outfile:
for o in range(0, len(prog_input), 3):
print(','.join(map(str, prog_input[o:o+3])), file=outfile)

', '.join([str(item) for item in prog_input]
This loops over the entire list and joins all of the elements with comma delimiters. If you want the output to be something else, then you need to do this differently.
I suggest describing in words what you want to do. From your example, it appears that you first need to take the list and subdivide it into lists with three elements each. I leave writing code to do that as an exercise to the reader.

Move the \n to the right location
This:
', '.join([str(item) for item in prog_input])+ '\n'
Should be :
',\n'.join([str(item) for item in prog_input])
Edit:
If you want only 3 elements on each line you can use:
',\n'.join([', '.join([str(j) for j in prog_input[i:i+3]]) for i in range(0, len(prog_input), 3)])

how to remove "\n" from a list of strings

I have a list that is read from a text file that outputs:
['/Users/myname/Documents/test1.txt\n', '/Users/myname/Documents/test2.txt\n', '/Users/myname/Documents/test3.txt\n']
I want to remove the \n from each element, but using .split() does not work on lists only strings (which is annoying as this is a list of strings).
How do I remove the \n from each element so I can get the following output:
['/Users/myname/Documents/test1.txt', '/Users/myname/Documents/test2.txt', '/Users/myname/Documents/test3.txt']

old_list = [x.strip() for x in old_list]
old_list refers to the list you want to remove the \n from.
Or if you want something more readable:
for x in range(len(old_list)):
old_list[x] = old_list[x].strip()
Does the same thing, without list comprehension.
strip() method takes out all the whitespaces, including \n.
But if you are not ok with the idea of removing whitespaces from start and end, you can do:
old_list = [x.replace("\n", "") for x in old_list]
or
for x in range(len(old_list)):
old_list[x] = old_list[x].replace("\n", "")

do a strip but keep in mind that the result is not modifying the original list, so you will need to reasign it if required:
a = ['/Users/myname/Documents/test1.txt\n', '/Users/myname/Documents/test2.txt\n', '/Users/myname/Documents/test3.txt\n']
a = [path.strip() for path in a]
print a

Give this code a try:
lst = ['/Users/myname/Documents/test1.txt\n', '/Users/myname/Documents/test2.txt\n', '/Users/myname/Documents/test3.txt\n']
for n, element in enumerate(lst):
element = element.replace('\n', '')
lst[n] = element
print(lst)

Use:
[i.strip() for i in lines]
in case you don't mind to lost the spaces and tabs at the beginning and at the end of the lines.

You can read the whole file and split lines using str.splitlines:
temp = file.read().splitlines()
if you still have problems go to this question where I got the answer from
How to read a file without newlines?
answered Sep 8 '12 at 11:57 Bakuriu

There are many ways to achieve your result.
Method 1: using split() method
l = ['/Users/myname/Documents/test1.txt\n', '/Users/myname/Documents/test2.txt\n', '/Users/myname/Documents/test3.txt\n']
result = [i.split('\n')[0] for i in l]
print(result) # ['/Users/myname/Documents/test1.txt', '/Users/myname/Documents/test2.txt', '/Users/myname/Documents/test3.txt']
Method 2: using strip() method that removes leading and trailing whitespace
l = ['/Users/myname/Documents/test1.txt\n', '/Users/myname/Documents/test2.txt\n', '/Users/myname/Documents/test3.txt\n']
result = [i.strip() for i in l]
print(result) # ['/Users/myname/Documents/test1.txt', '/Users/myname/Documents/test2.txt', '/Users/myname/Documents/test3.txt']
Method 3: using rstrip() method that removes trailing whitespace
l = ['/Users/myname/Documents/test1.txt\n', '/Users/myname/Documents/test2.txt\n', '/Users/myname/Documents/test3.txt\n']
result = [i.rstrip() for i in l]
print(result) # ['/Users/myname/Documents/test1.txt', '/Users/myname/Documents/test2.txt', '/Users/myname/Documents/test3.txt']
Method 4: using the method replace
l = ['/Users/myname/Documents/test1.txt\n', '/Users/myname/Documents/test2.txt\n', '/Users/myname/Documents/test3.txt\n']
result = [i.replace('\n', '') for i in l]
print(result) # ['/Users/myname/Documents/test1.txt', '/Users/myname/Documents/test2.txt', '/Users/myname/Documents/test3.txt']

Here is another way to do it with lambda:
cleannewline = lambda somelist : map(lambda element: element.strip(), somelist)
Then you can just call it as:
cleannewline(yourlist)

Remove "\n" with strip in Python?

I'm working on a file text, but, as it has spaces at the beginning too, when I try to delete my \n using the strip mode and list comprehension, I get a list with empty elements (" ") and I don't know how to delete them.
I have a text and my code is:
with open(filename) as f:
testo= f.readlines()
[e.strip() for e in testo]
but I get a list like this:
[' ', ' ', 'word1', 'word2', 'word3', ' ']
I wanted to know if I can work it out with the strip method, otherwise with another method.

You can use a generator to read all the lines and strip() the unwanted newlines.
From the generator you only use those elements that are "Truthy" - empty strings are considered False.
Advantage: you create only one list and get rid of empty strings:
Write file:
filename = "t.txt"
with open(filename,"w") as f:
f.write("""
c
oo
l
te
xt
""")
Process file:
with open(filename) as f:
testo = [x for x in (line.strip() for line in f) if x] # f.readlines() not needed. f is
# an iterable in its own right
print(testo) # ['c', 'oo', 'l', 'te', 'xt']
You could do the similarly:
testo = [line.strip() for line in f if line.strip()]
but that would execute strip() twice and would be slightly less efficient.
Output:
['c', 'oo', 'l', 'te', 'xt']
Doku:
strip()
truth value testing
A suggested alternative from Eli Korvigo is:
testo = list(filter(bool, map(str.strip, f)))
with is essentially the same - replacing the explicit list comp using a generator comp with a map of str.strip on f (resulting in a generator) and applying a filter to that to feed it into a list.
See built in function for the docu of filter,map,bool.
I like mine better though ;o)

You are getting those empty string because few of lines were just empty line breaks. Here's the code for weeding out these empty strings.
with open(filename) as f:
testo = [e.strip() for e in f.readlines()]
final_list = list(filter(lambda x: x != '', testo))
print(final_list)
Without lambda and using map:
with open(filename) as f:
final_list = list(filter(bool, map(str.strip, f)))
print(final_list)
Another solution is:
with open(filename) as f:
testo = [x for x in f.read().splitlines() if x]
print(testo)
For second solution is source is:
https://stackoverflow.com/a/15233379/2988776
For performance upgrades refer to #Patrick 's answer

From the data you showed us, it looks like there is a line with just a space in it. With that in mind, you have to decide whether this is something you want or not.
In case you want it, then your code should look something like this:
with open(filename) as f:
testo=f.readlines()
list(filter(None, (l.rstrip('\n') for l in testo)))
In case you don't want lines with just whitespace characters, you can do something like:
with open(filename) as f:
testo=f.readlines()
[e.rstrip('\n') for e in testo if e.strip()]
In this case, we avoid stripping the: " a word with leading and trailing spaces " to "a word with leading and trailing spaces", since in some cases it might change the semantics of the line:)

Creating lists from rows with different lengths in python

I am trying to create a list for each column in python of my data that looks like this:
399.75833 561.572000000 399.75833 561.572000000 a_Fe I 399.73920 nm
399.78316 523.227000000 399.78316 523.227000000
399.80799 455.923000000 399.80799 455.923000000 a_Fe I 401.45340 nm
399.83282 389.436000000 399.83282 389.436000000
399.85765 289.804000000 399.85765 289.804000000
The problem is that each row of my data is a different length. Is there anyway to format the remaining spaces of the shorter rows with a space so they are all the same length?
I would like my data to be in the form:
list one= [399.75833, 399.78316, 399.80799, 399.83282, 399.85765]
list two= [561.572000000, 523.227000000, 455.923000000, 389.436000000, 289.804000000]
list three= [a_Fe, " ", a_Fe, " ", " "]
This is the code I used to import the data into python:
fh = open('help.bsp').read()
the_list = []
for line in fh.split('\n'):
print line.strip()
splits = line.split()
if len(splits) ==1 and splits[0]== line.strip():
splits = line.strip().split(',')
if splits:the_list.append(splits)

You need to use izip_longest to make your column lists, since standard zip will only run till the shortest length in the given list of arrays.
from itertools import izip_longest
with open('workfile', 'r') as f:
fh = f.readlines()
# Process all the rows line by line
rows = [line.strip().split() for line in fh]
# Use izip_longest to get all columns, with None's filled in blank spots
cols = [col for col in izip_longest(*rows)]
# Then run your type conversions for your final data lists
list_one = [float(i) for i in cols[2]]
list_two = [float(i) for i in cols[3]]
# Since you want " " instead of None for blanks
list_three = [i if i else " " for i in cols[4]]
Output:
>>> print list_one
[399.75833, 399.78316, 399.80799, 399.83282, 399.85765]
>>> print list_two
[561.572, 523.227, 455.923, 389.436, 289.804]
>>> print list_three
['a_Fe', ' ', 'a_Fe', ' ', ' ']

So, your lines are either whitespace delimited or comma delimited, and if comma delimited, the line contains no whitespace? (note that if len(splits)==1 is true, then splits[0]==line.strip() is also true). That's not the data you're showing, and not what you're describing.
To get the lists you want from the data you show:
with open('help.bsp') as h:
the_list = [ line.strip().split() for line in h.readlines() ]
list_one = [ d[0] for d in the_list ]
list_two = [ d[1] for d in the_list ]
list_three = [ d[4] if len(d) > 4 else ' ' for d in the_list ]
If you're reading comma separated (or similarly delimited) files, I always recommend using the csv module - it handles a lot of edge cases that you may not have considered.

Change the display of a list took from text file

I have this code wrote in Python:
with open ('textfile.txt') as f:
list=[]
for line in f:
line = line.split()
if line:
line = [int(i) for i in line]
list.append(line)
print(list)
This actually read integers from a text file and put them in a list.But it actually result as :
[[10,20,34]]
However,I would like it to display like:
10 20 34
How to do this? Thanks for your help!

You probably just want to add the items to the list, rather than appending them:
with open('textfile.txt') as f:
list = []
for line in f:
line = line.split()
if line:
list += [int(i) for i in line]
print " ".join([str(i) for i in list])
If you append a list to a list, you create a sub list:
a = [1]
a.append([2,3])
print a # [1, [2, 3]]
If you add it you get:
a = [1]
a += [2,3]
print a # [1, 2, 3]!

with open('textfile.txt') as f:
lines = [x.strip() for x in f.readlines()]
print(' '.join(lines))
With an input file 'textfiles.txt' that contains:
10
20
30
prints:
10 20 30

It sounds like you are trying to print a list of lists. The easiest way to do that is to iterate over it and print each list.
for line in list:
print " ".join(str(i) for i in line)
Also, I think list is a keyword in Python, so try to avoid naming your stuff that.

If you know that the file is not extremely long, if you want the list of integers, you can do it at once (two lines where one is the with open(.... And if you want to print it your way, you can convert the element to strings and join the result via ' '.join(... -- like this:
#!python3
# Load the content of the text file as one list of integers.
with open('textfile.txt') as f:
lst = [int(element) for element in f.read().split()]
# Print the formatted result.
print(' '.join(str(element) for element in lst))
Do not use the list identifier for your variables as it masks the name of the list type.