I've been stuck on this Python homework problem for awhile now: "Write a complete python program that reads 20 real numbers from a file inner.txt and outputs them in sorted order to a file outter.txt."
Alright, so what I do is:
f=open('inner.txt','r')
n=f.readlines()
n.replace('\n',' ')
n.sort()
x=open('outter.txt','w')
x.write(print(n))
So my thought process is: Open the text file, n is the list of read lines in it, I replace all the newline prompts in it so it can be properly sorted, then I open the text file I want to write to and print the list to it. First problem is it won't let me replace the new line functions, and the second problem is I can't write a list to a file.
I just tried this:
>>> x= "34\n"
>>> print(int(x))
34
So, you shouldn't have to filter out the "\n" like that, but can just put it into int() to convert it into an integer. This is assuming you have one number per line and they're all integers.
You then need to store each value into a list. A list has a .sort() method you can use to then sort the list.
EDIT:
forgot to mention, as other have already said, you need to iterate over the values in n as it's a list, not a single item.
Here's a step by step solution that fixes the issues you have :)
Opening the file, nothing wrong here.
f=open('inner.txt','r')
Don't forget to close the file:
f.close()
n is now a list of each line:
n=f.readlines()
There are no list.replace methods, so I suggest changing the above line to n = f.read(). Then, this will work (don't forget to reassign n, as strings are immutable):
n = n.replace('\n','')
You still only have a string full of numbers. However, instead of replacing the newline character, I suggest splitting the string using the newline as a delimiter:
n = n.split('\n')
Then, convert these strings to integers:
`n = [int(x) for x in n]`
Now, these two will work:
n.sort()
x=open('outter.txt','w')
You want to write the numbers themselves, so use this:
x.write('\n'.join(str(i) for i in n))
Finally, close the file:
x.close()
Using a context manager (the with statement) is good practice as well, when handling files:
with open('inner.txt', 'r') as f:
# do stuff with f
# automatically closed at the end
I guess real means float. So you have to convert your results to float to sort properly.
raw_lines = f.readlines()
floats = map(float, raw_lines)
Then you have to sort it. To write result back, you have to convert to string and join with line endings:
sortеd_as_string = map(str, sorted_floats)
result = '\n'.join(sortеd_as_string)
Finally you have have to write result to destination.
Ok let's look it step by step what you want to do.
First: Read some integers out of a textfile.
Pythonic Version:
fileNumbers = [int(line) for line in open(r'inner.txt', 'r').readlines()]
Easy to get version:
fileNumbers = list()
with open(r'inner.txt', 'r') as fh:
for singleLine in fh.readlines():
fileNumbers.append(int(singleLine))
What it does:
Open the file
Read each line, convert it to int (because readlines return string values) and append it to the list fileNumbers
Second: Sort the list
fileNumbers.sort()
What it does:
The sort function sorts the list by it's value e.g. [5,3,2,4,1] -> [1,2,3,4,5]
Third: Write it to a new textfile
with open(r'outter.txt', 'a') as fh:
[fh.write('{0}\n'.format(str(entry))) for entry in fileNumbers]
Related
I have a function gen_rand_index that generates a random group of numbers in list format, such as [3,1] or [3,2,1]
I also have a textfile that that reads something like this:
red $1
green $5
blue $6
How do I write a function so that once python generates this list of numbers, it automatically reads that # line in the text file? So if it generated [2,1], instead of printing [2,1] I would get "green $5, red $1" aka the second line in the text file and the first line in the text file?
I know that you can do print(line[2]) and commands like that, but this won't work in my case because each time I am getting a different random number of a line that I want to read, it is not a set line I want to read each time.
row = str(result[gen_rand_index]) #result[gen_rand_index] gives me the random list of numbers
file = open("Foodinventory.txt", 'r')
for line in file:
print(line[row])
file.close()
I have this so far, but I am getting this
error: invalid literal for int() with base 10: '[4, 1]'
I also have gotten
TypeError: string indices must be integers
butI have tried replacing str with int and many things like that but I'm thinking the way I'm just approaching this is wrong. Can anyone help me? (I have only been coding for a couple days now so I apologize in advance if this question is really basic)
Okay, let us first get some stuff out of the way
Whenever you access something from a list the thing you put inside the box brackets [] should be an integer, eg: [5]. This tells Python that you want the 5th element. It cannot ["5"] because 5 in this case would be treated as a string
Therefore the line row = str(result[gen_rand_index]) should actually just be row = ... without the call to str. This is why you got the TypeError about list indices
Secondly, as per your description gen_rand_index would return a list of numbers.
So going by that, why don;t you try this
indices_to_pull = gen_rand_index()
file_handle = open("Foodinventory.txt", 'r')
file_contents = file_handle.readlines() # If the file is small and simle this would work fine
answer = []
for index in indices_to_pull:
answer.append(file_contents[index-1])
Explanation
We get the indices of the file lines from gen_rand_index
we read the entire file into memory using readlines()
Then we get the lines we want, Rememebr to subtract 1 as the list is indexed from 0
The error you are getting is because you're trying to index a string variable (line) with a string index (row). Presumably row will contain something like '[2,3,1]'.
However, even if row was a numerical index, you're not indexing what you think you're indexing. The variable line is a string, and it contains (on any given iteration) one line of the file. Indexing this variable will give you a single character. For example, if line contains green $5, then line[2] will yield 'e'.
It looks like your intent is to index into a list of strings, which represent all the lines of the file.
If your file is not overly large, you can read the entire file into a list of lines, and then just index that array:
with open('file.txt') as fp:
lines = fp.readlines()
print(lines[2]).
In this case, lines[2] will yield the string 'blue $6\n'.
To discard the trailing newline, use lines[2].strip() instead.
I'll go line by line and raise some issues.
row = str(result[gen_rand_index]) #result[gen_rand_index] gives me the random list of numbers
Are you sure it is gen_rand_index and not gen_rand_index()? If gen_rand_index is a function, you should call the function. In the code you have, you are not calling the function, instead you are using the function directly as an index.
file = open("Foodinventory.txt", 'r')
for line in file:
print(line[row])
file.close()
The correct python idiom for opening a file and reading line by line is
with open("Foodinventory.txt.", "r") as f:
for line in f:
...
This way you do not have to close the file; the with clause does this for you automatically.
Now, what you want to do is to print the lines of the file that correspond to the elements in your variable row. So what you need is an if statement that checks if the line number you just read from the file corresponds to the line number in your array row.
with open("Foodinventory.txt", "r") as f:
for i, line in enumerate(f):
if i == row[i]:
print(line)
But this is wrong: it would work only if your list's elements are ordered. That is not the case in your question. So let's think a little bit. You could iterate over your file multiple times, and each time you iterate over it, print out one line. But this will be inefficient: it will take time O(nm) where n==len(row) and m == number of lines in your file.
A better solution is to read all the lines of the file and save them to an array, then print the corresponding indices from this array:
arr = []
with open("Foodinventory.txt", "r") as f:
arr = list(f)
for i in row:
print(arr[i - 1]) # arrays are zero-indiced
I have the text files as below format in single line,
username:password;username1:password1;username2:password2;
etc.
What I have tried so far is
with open('list.txt') as f:
d = dict(x.rstrip().split(None, 1) for x in f)
but I get an error saying that the length is 1 and 2 is required which indicates the file is not being as key:value.
Is there any way to fix this or should I just reformat the file in another way?
thanks for your answers.
What i got so far is:
with open('tester.txt') as f:
password_list = dict(x.strip(":").split(";", 1) for x in f)
for user, password in password_list.items():
print(user + " - " + password)
the results comes out as username:password - username1:password1
what i need is to split username:password where key = user and value = password
Since variable f in this case is a file object and not a list, the first thing to do would be to get the lines from it. You could use the https://docs.python.org/2/library/stdtypes.html?highlight=readline#file.readlines* method for this.
Furthermore, I think I would use strip with the semicolon (";") parameter. This will provide you with a list of strings of "username:password", provided your entire file looks like this.
I think you will figure out what to do after that.
EDIT
* I auto assumed you use Python 2.7 for some reason. In version 3.X you might want to look at the "distutils.text_file" (https://docs.python.org/3.7/distutils/apiref.html?highlight=readlines#distutils.text_file.TextFile.readlines) class.
Load the text of the file in Python with open() and read() as a string
Apply split(;) to that string to create a list like [username:password, username1:password1, username2:password2]
Do a dict comprehension where you apply split(":") to each item of the above list to split those pairs.
with open('list.txt', 'rt') as f:
raw_data = f.readlines()[0]
list_data = raw_data.split(';')
user_dict = { x.split(':')[0]:x.split(':')[1] for x in list_data }
print(user_dict)
Dictionary comprehension is useful here.
One liner to pull all the info out of the text file. As requested. Hope your tutor is impressed. Ask him How it works and see what he says. Maybe update your question to include his response.
If you want me to explain, feel free to comment and I shall go into more detail.
The error you're probably getting:
ValueError: dictionary update sequence element #3 has length 1; 2 is required
is because the text line ends with a semicolon. Splitting it on semicolons then results in a list that contains some pairs, and an empty string:
>>> "username:password;username1:password1;username2:password2;".split(";")
['username:password', 'username1:password1', 'username2:password2', '']
Splitting the empty string on colons then results in a single empty string, rather than two strings.
To fix this, filter out the empty string. One example of doing this would be
[element for element in x.split(";") if element != ""]
In general, I recommend you do the work one step at a time and assign to intermediary variables.
Here's a simple (but long) answer. You need to get the line from the file, and then split it and the items resulting from the split:
results = {}
with open('file.txt') as file:
for line in file:
#Only one line, but that's fine
entries = line.split(';')
for entry in entries:
if entry != '':
#The last item in entries will be blank, due to how split works in this example
user, password = entry.split(':')
results[user] = password
Try this.
f = open('test.txt').read()
data = f.split(";")
d = {}
for i in data:
if i:
value = i.split(":")
d.update({value[0]:value[1]})
print d
I'm doing Euler Problems and am at problem #8 and wanted to just copy this huge 1000-digit number to a numberToProblem8.txt file and then just read it into my script but I can't find a good way to remove newlines from it. With that code:
hugeNumberAsStr = ''
with open('numberToProblem8.txt') as f:
for line in f:
aSingleLine = line.strip()
hugeNumberAsStr.join(aSingleLine)
print(hugeNumberAsStr)
Im using print() to only check if it works and well, it doesnt. It doesnt print out anything. What's wrong with my code? I remove all the trash with strip() and then use join() to add that cleaned line into hugeNumberAsStr (need a string to join those lines, gonna use int() later on) and its repeated for all the lines.
Here is the .txt file with a number in it.
What about something like:
hugeNumberAsStr = open('numberToProblem8.txt').read()
hugeNumberAsStr = hugeNumberAsStr.strip().replace('\n', '')
Or even:
hugeNumberAsStr = ''.join([d for d in hugeNumberAsStr if d.isdigit()])
I was able to simplify it to the following to get the number from that file:
>>> int(open('numberToProblem8.txt').read().replace('\n',''))
731671765313306249192251196744265747423553491949349698352031277450632623957831801698480186947885184385861560789112949495459501737958331952853208805511125406987471585238630507156932909632952274430435576689664895044524452316173185640309871112172238311362229893423380308135336276614282806444486645238749303589072962904915604407723907138105158593079608667017242712188399879790879227492190169972088809377665727333001053367881220235421809751254540594752243525849077116705560136048395864467063244157221553975369781797784617406495514929086256932197846862248283972241375657056057490261407972968652414535100474821663704844031998900088952434506585412275886668811642717147992444292823086346567481391912316282458617866458359124566529476545682848912883142607690042242190226710556263211111093705442175069416589604080719840385096245544
You need to do hugeNumberAsStr += aSingleLine instead of hugeNumberAsStr.join(..)
str.join() joins the passed iterator and return the string value joined by str. It doesn't update the value of hugeNumberAsStr as you think. You want to create a new string with removed \n. You need to store these values in new string. For that you need append the content to the string
The join method for strings simply takes an iterable object and concatenates each part together. It then returns the resulting concatenated string. As stated in help(str.join):
join(...)
S.join(iterable) -> str
Return a string which is the concatenation of the strings in the
iterable. The separator between elements is S.
Thus the join method really does not do what you want.
The concatenation line should be more like:
hugeNumberAsString += aSingleLine
Or even:
hugeNumberAsString += line.strip()
Which gets rid of the extra line of code doing the strip.
In Python:
Let's say I have a loop, during each cycle of which I produce a list with the following format:
['n1','n2','n3']
After each cycle I would like to write to append the produced entry to a file (which contains all the outputs from the previous cycles). How can I do that?
Also, is there a way to make a list whose entries are the outputs of this cycle? i.e.
[[],[],[]] where each internal []=['n1','n2','n3] etc
Writing single list as a line to file
Surely you can write it into a file like, after converting it to string:
with open('some_file.dat', 'w') as f:
for x in xrange(10): # assume 10 cycles
line = []
# ... (here is your code, appending data to line) ...
f.write('%r\n' % line) # here you write representation to separate line
Writing all lines at once
When it comes to the second part of your question:
Also, is there a way to make a list whose entries are the outputs of this cycle? i.e. [[],[],[]] where each internal []=['n1','n2','n3'] etc
it is also pretty basic. Assuming you want to save it all at once, just write:
lines = [] # container for a list of lines
for x in xrange(10): # assume 10 cycles
line = []
# ... (here is your code, appending data to line) ...
lines.append('%r\n' % line) # here you add line to the list of lines
# here "lines" is your list of cycle results
with open('some_file.dat', 'w') as f:
f.writelines(lines)
Better way of writing a list to file
Depending on what you need, you should probably use one of the more specialized formats, than just a text file. Instead of writing list representations (which are okay, but not ideal), you could use eg. csv module (similar to Excel's spreadsheet): http://docs.python.org/3.3/library/csv.html
f=open(file,'a') first para is the path of file,second is the pattern,'a' is append,'w' is write, 'r' is read ,and so on
im my opinion,you can use f.write(list+'\n') to write a line in a loop ,otherwise you can use f.writelines(list),it also functions.
Hope this can help you:
lVals = []
with open(filename, 'a') as f:
for x,y,z in zip(range(10), range(5, 15), range(10, 20)):
lVals.append([x,y,z])
f.write(str(lVals[-1]))
I'm somewhat new to python. I'm trying to sort through a list of strings and integers. The lists contains some symbols that need to be filtered out (i.e. ro!ad should end up road). Also, they are all on one line separated by a space. So I need to use 2 arguments; one for the input file and then the output file. It should be sorted with numbers first and then the words without the special characters each on a different line. I've been looking at loads of list functions but am having some trouble putting this together as I've never had to do anything like this. Any takers?
So far I have the basic stuff
#!/usr/bin/python
import sys
try:
infilename = sys.argv[1] #outfilename = sys.argv[2]
except:
print "Usage: ",sys.argv[0], "infile outfile"; sys.exit(1)
ifile = open(infilename, 'r')
#ofile = open(outfilename, 'w')
data = ifile.readlines()
r = sorted(data, key=lambda item: (int(item.partition(' ')[0])
if item[0].isdigit() else float('inf'), item))
ifile.close()
print '\n'.join(r)
#ofile.writelines(r)
#ofile.close()
The output shows exactly what was in the file but exactly as the file is written and not sorted at all. The goal is to take a file (arg1.txt) and sort it and make a new file (arg2.txt) which will be cmd line variables. I used print in this case to speed up the editing but need to have it write to a file. That's why the output file areas are commented but feel free to tell me I'm stupid if I screwed that up, too! Thanks for any help!
When you have an issue like this, it's usually a good idea to check your data at various points throughout the program to make sure it looks the way you want it to. The issue here seems to be in the way you're reading in the file.
data = ifile.readlines()
is going to read in the entire file as a list of lines. But since all the entries you want to sort are on one line, this list will only have one entry. When you try to sort the list, you're passing a list of length 1, which is going to just return the same list regardless of what your key function is. Try changing the line to
data = ifile.readlines()[0].split()
You may not even need the key function any more since numbers are placed before letters by default. I don't see anything in your code to remove special characters though.
since they are on the same line you dont really need readlines
with open('some.txt') as f:
data = f.read() #now data = "item 1 item2 etc..."
you can use re to filter out unwanted characters
import re
data = "ro!ad"
fixed_data = re.sub("[!?#$]","",data)
partition maybe overkill
data = "hello 23frank sam wilbur"
my_list = data.split() # ["hello","23frank","sam","wilbur"]
print sorted(my_list)
however you will need to do more to force numbers to sort maybe something like
numbers = [x for x in my_list if x[0].isdigit()]
strings = [x for x in my_list if not x[0].isdigit()]
sorted_list = sorted(numbers,key=lambda x:int(re.sub("[^0-9]","",x))) + sorted(strings(
Also, they are all on one line separated by a space.
So your file contains a single line?
data = ifile.readlines()
This makes data into a list of the lines in your file. All 1 of them.
r = sorted(...)
This makes r the sorted version of that list.
To get the words from the line, you can .read() the entire file as a single string, and .split() it (by default, it splits on whitespace).