I want to create a text file which contains positive/negative numbers separated by ','.
i want to read this file and put it in data = []. i have written the code below and i think that it works well.
I want to ask if you guys know a better way to do it or if is it well written
thanks all
#!/usr/bin/python
if __name__ == "__main__":
#create new file
fo = open("foo.txt", "w")
fo.write( "111,-222,-333");
fo.close()
#read the file
fo = open("foo.txt", "r")
tmp= []
data = []
count = 0
tmp = fo.read() #read all the file
for i in range(len(tmp)): #len is 11 in this case
if (tmp[i] != ','):
count+=1
else:
data.append(tmp[i-count : i])
count = 0
data.append(tmp[i+1-count : i+1])#append the last -333
print data
fo.close()
You can use split method with a comma as a separator:
fin = open('foo.txt')
for line in fin:
data.extend(line.split(','))
fin.close()
Instead of looping through, you can just use split:
#!/usr/bin/python
if __name__ == "__main__":
#create new file
fo = open("foo.txt", "w")
fo.write( "111,-222,-333");
fo.close()
#read the file
with open('foo.txt', 'r') as file:
data = [line.split(',') for line in file.readlines()]
print(data)
Note that this gives back a list of lists, with each list being from a separate line. In your example you only have one line. If your files will always only have a single line, you can just take the first element, data[0]
To get the whole file content(numbers positive and negative) into list you can use split and splitlines
file_obj = fo.read()#read your content into string
list_numbers = file_obj.replace('\n',',').split(',')#split on ',' and newline
print list_numbers
Related
here is what I got txt and open
txt file looks like
f = open('data.txt', 'r')
print(f.read())
the show['Cat\n','Dog\n','Cat\n','Dog\n'........]
output
But I would like to get this
['C\n','D\n','C\n','D\n'........]
First you'll want to open the file in read mode (r flag in open), then you can iterate through the file object with a for loop to read each line one at a time. Lastly, you want to access the first element of each line at index 0 to get the first letter.
first_letters = []
with open('data.txt', 'r') as f:
for line in f:
first_letters.append(line[0])
print(first_letters)
If you want to have the newline character still present in the string you can modify line 5 from above to:
first_letters.append(line[0] + '\n')
f = open("data.txt", "r")
for x in f:
print(x[0])
f.close()
I have a file (list.txt) with huge array like this:
['1458575', '1458576', '1458577', '1458578'...]
I want to read it in my script but the output is white. The goal is print the number of line (list.txt) of the file.txt
numbers_line = open("list.txt", "r")
lines = numbers_line.readlines().split(',')
i=0
f=open('file.txt')
for line in f:
if i in lines:
print (line)
i+=1
However, if I put the array direct it's read, but considering that is a huge array this is not could be helpful.
lines=['1458575', '1458576', '1458577', '1458578', '1458579', '1458580', '1458581', '1458582', '1458583', '1458584']
i=0
f=open('file.txt')
for line in f:
if i in lines:
print (line)
i+=1
Thanks for your support
readlines returns list of lines, not string
readline will return a string, but split(',') would give a list of string not int
try this
import ast
text_file = open("list.txt", "r")
lines = list(map(int, ast.literal_eval(text_file.read().strip())))
i=0
f=open('file.txt')
for line in f:
if i in lines:
print (line)
i+=1
This can work
with open('file.txt') as file:
content = file.read()
a = []
exec('a = ' + content) # executes - a = ['1458575', ...]
Alternate method - copy file.txt to new file my_lists.py.
Add 'a = ' at the start of my_lists.py file and execute
from my_lists import a
Use with open() as : instead of open() and close(), because it closes the connection to file automatically when errors occurs while the traditional manual open() and close() don't do.
lines=['1458575', '1458576', '1458577', '1458578', '1458579', '1458580', '1458581', '1458582', '1458583', '1458584']
lines = [int(x) for x in lines] # convert to integers
fpath = "list.txt"
with open(fpath, "r") as f:
for x in f:
x = x.trim() # remove end of line character
if int(x) in lines:
print(x)
I'm new to python hence I am unable to implement the solutions I've found online in order to fix my problem.
I am trying to add a specific string to the end of a specific line to a textfile. As I understand text commands, I must overwrite the file if I don't want to append to the end of it. So, my solution is as follows:
ans = 'test'
numdef = ['H',2]
f = open(textfile, 'r')
lines = f.readlines()
f.close()
f = open(textfile, 'w')
f.write('')
f.close()
f = open(textfile, 'a')
for line in lines:
if int(line[0]) == numdef[1]:
if str(line[2]) == numdef[0]:
k = ans+ line
f.write(k)
else:
f.write(line)
Basically, I am trying to add variable ans to the end of a specific line, the line which appears in my list numdef. So, for example, for
2 H: 4,0 : Where to search for information : google
I want
2 H: 4,0 : Where to search for information : google test
I have also tried using line.insert() but to no avail.
I understand using the 'a' function of the open command is not so relevant and helpful here, but I am out of ideas. Would love tips with this code, or if maybe I should scrap it and rethink the whole thing.
Thank you for your time and advice!
When you use the method
lines = f.readlines()
Python automatically adds "\n" to the end of each line.
Try instead of :
k = line+ans
The following:
k = line.rstrip('\n') + ans
Good luck!
Try this. You don't have an else case if it meets the first requirement but not the other.
ans = 'test'
numdef = ['H',2]
f = open(textfile, 'r')
lines = f.readlines()
f.close()
f = open(textfile, 'w')
f.write('')
f.close()
f = open(textfile, 'a')
for line in lines:
if int(line[0]) == numdef[1] and str(line[2]) == numdef[0]:
k = line.replace('\n','')+ans
f.write(k)
else:
f.write(line)
f.close()
Better way:
#initialize variables
ans = 'test'
numdef = ['H',2]
#open file in read mode, add lines into lines
with open(textfile, 'r') as f:
lines=f.readlines()
#open file in write mode, override everything
with open(textfile, 'w') as f:
#in the list comprehension, loop through each line in lines, if both of the conditions are true, then take the line, remove all newlines, and add ans. Otherwise, remove all the newlines and don't add anything. Then combine the list into a string with newlines as separators ('\n'.join), and write this string to the file.
f.write('\n'.join([line.replace('\n','')+ans if int(line[0]) == numdef[1] and str(line[2]) == numdef[0] else line.replace('\n','') for line in lines]))
I am trying to code something where I first look for some string in a line in a txt file and when it is found I want to skip that row and the row below to get a new txt file without those rows. I really didn't get any solution from other questions here so maybe this will work
My code looks like this now:
with open("bla.txt", "r+") as f
new_f = f.readlines()
f.seek(0)
for line in new_f:
if "abc" not in line:
f.write(line)
else:
pass
pass
f.truncate()
I tried it with next(f) aswell but it didn't work for me. thanks in advance
This code creates a new file that skip the current and next row if the current row has the string ABC:
with open('bla.txt','r') as f:
text = f.read()
lines = text.split('\n')
with open('new_file.txt','w') as nf:
l = 0
while l<(len(lines)):
if 'ABC' in lines[l]:
l = l+2
else:
nf.write(lines[l]+'\n')
l = l+1
Try something simple like this:
import os
search_for = 'abc'
with open('input.txt') as f, open('output.txt', 'w') as o:
for line in f:
if search_for in line:
next(f) # we need to skip the next line
# since we are already processing
# the line with the string
# in effect, it skips two lines
else:
o.write(line)
os.rename('output.txt', 'input.txt')
Here is a repl with sample code.
I'm new to python and the way it handles variables and arrays of variables in lists is quite alien to me. I would normally read a text file into a vector and then copy the last three into a new array/vector by determining the size of the vector and then looping with a for loop a copy function for the last size-three into a new array.
I don't understand how for loops work in python so I can't do that.
so far I have:
#read text file into line list
numberOfLinesInChat = 3
text_file = open("Output.txt", "r")
lines = text_file.readlines()
text_file.close()
writeLines = []
if len(lines) > numberOfLinesInChat:
i = 0
while ((numberOfLinesInChat-i) >= 0):
writeLine[i] = lines[(len(lines)-(numberOfLinesInChat-i))]
i+= 1
#write what people say to text file
text_file = open("Output.txt", "w")
text_file.write(writeLines)
text_file.close()
To get the last three lines of a file efficiently, use deque:
from collections import deque
with open('somefile') as fin:
last3 = deque(fin, 3)
This saves reading the whole file into memory to slice off what you didn't actually want.
To reflect your comment - your complete code would be:
from collections import deque
with open('somefile') as fin, open('outputfile', 'w') as fout:
fout.writelines(deque(fin, 3))
As long as you're ok to hold all of the file lines in memory, you can slice the list of lines to get the last x items. See http://docs.python.org/2/tutorial/introduction.html and search for 'slice notation'.
def get_chat_lines(file_path, num_chat_lines):
with open(file_path) as src:
lines = src.readlines()
return lines[-num_chat_lines:]
>>> lines = get_chat_lines('Output.txt', 3)
>>> print(lines)
... ['line n-3\n', 'line n-2\n', 'line n-1']
First to answer your question, my guress is that you had an index error you should replace the line writeLine[i] with writeLine.append( ). After that, you should also do a loop to write the output :
text_file = open("Output.txt", "w")
for row in writeLine :
text_file.write(row)
text_file.close()
May I suggest a more pythonic way to write this ? It would be as follow :
with open("Input.txt") as f_in, open("Output.txt", "w") as f_out :
for row in f_in.readlines()[-3:] :
f_out.write(row)
A possible solution:
lines = [ l for l in open("Output.txt")]
file = open('Output.txt', 'w')
file.write(lines[-3:0])
file.close()
This might be a little clearer if you do not know python syntax.
lst_lines = lines.split()
This will create a list containing all the lines in the text file.
Then for the last line you can do:
last = lst_lines[-1]
secondLAst = lst_lines[-2]
etc... list and string indexes can be reached from the end with the '-'.
or you can loop through them and print specific ones using:
start = start line, stop = where to end, step = what to increment by.
for i in range(start, stop-1, step):
string = lst_lines[i]
then just write them to a file.