So I am completely new to Python and can't figure out what's wrong with my code.
I need to write a program that asks for the name of the existing text file and then of the other one, that doesn't necessarily need to exist. The task of the program is to take content of the first file, convert it to upper-case letters and paste to the second file. Then it should return the number of symbols used in the file(s).
The code is:
file1 = input("The name of the first text file: ")
file2 = input("The name of the second file: ")
f = open(file1)
file1content = f.read()
f.close
f2 = open(file2, "w")
file2content = f2.write(file1content.upper())
f2.close
print("There is ", len(str(file2content)), "symbols in the second file.")
I created two text files to check whether Python performs the operations correctly. Turns out the length of the file(s) is incorrect as there were 18 symbols in my file(s) and Python showed there were 2.
Could you please help me with this one?
Issues I see with your code:
close is a method, so you need to use the () operator otherwise f.close does not do what your think.
It is usually preferred in any case to use the with form of opening a file -- then it is close automatically at the end.
the write method does not return anything, so file2content = f2.write(file1content.upper()) is None
There is no reason the read the entire file contents in; just loop over each line if it is a text file.
(Not tested) but I would write your program like this:
file1 = input("The name of the first text file: ")
file2 = input("The name of the second file: ")
chars=0
with open(file1) as f, open(file2, 'w') as f2:
for line in f:
f2.write(line.upper())
chars+=len(line)
print("There are ", chars, "symbols in the second file.")
input() does not do what you expect, use raw_input() instead.
Related
I have an exercise which I am struggling a lot with related to file handling in python. I tried a lot of times but keep on failing to create the program. Those are the 2 questions.
1) Write a program that takes as input a phrase and a path to a text file on the computer. The program should return either true if the phrase is present in the file or false if the phrase is not present in the file. Can you please help me to figure out those 2 questions. Thanks in advance.
2) Write a program that reads a csv file, where each line contains a coma-separated list of numbers and writes the sum of each line in another file. Use try-catch to handle potential errors such as empty lines or non-numeric values.
For question 1 I wrote:
phrase = input("Enter a phrase: ")
file = open("example.txt", "r")
if phrase in file:
print("True")
else:
print("False")
For question 2 I wrote:
file = open("example.csv", "r")
print(f.readlines())
try:
for i in file:
line = line + 1
file2 = open("lines.csv", "w")
file2.write(line)
file2.close
I am having trouble writing the entire list into an outfile. Here is the code:
with open(infline, "r") as f:
lines = f.readlines()
for l in lines:
if "ATOM" in l :
split = l.split()
if split[-1] == "1":
print(split)
#print(type(split))
with open( newFile,"w") as f:
f.write("Model Number One" + "\n")
f.write(str(split))
When I use print(split) it allows me to see the entire list (image below):
with open(infile, "r") as f:
lines = f.readlines()
for l in lines:
if "ATOM" in l :
split = l.split()
if split[-1] == "1":
#print(split)
print(type(split))
with open( newFile,"w") as f:
f.write("Model Number One" + "\n")
for i in range(len(split)):
f.write(str(split))
However, when I try to use f.write(split) I get an error because the function can only take a str not a list. So, I used f.write(str(split)) and it worked. The only issue now is that it only writes the last item in the list, not the whole list.
The function print is slightly more permissible than the method f.write, in the sense that it can accept lists and various types of objects as input. f.write is usually called by passing pre-formatted strings, as you noticed.
I think the issue with the code is that the write routine is nested inside the code. This causes Python to erase any contents stored inside newFile, and write only the last line read (l).
The problem can be easily fixed by changing the open call to open( newFile,"a"). The flag "a" tells Python to append the new contents to the existing file newFile (without erasing information). If newFile does not exist yet, Python will automatically create it.
sample input
in parsing a text file .txt = ["'blah.txt'", "'blah1.txt'", "'blah2.txt'" ]
the expected output in another text file out_path.txt
blah.txt
blah1.txt
blah2.txt
Code that I tried, this just appends "[]" to the input file. While I also tried perl one liner replacing double and single quotes.
read_out_fh = open('out_path.txt',"r")
for line in read_out_fh:
for word in line.split():
curr_line = re.findall(r'"(\[^"]*)"', '\n')
print(curr_line)
this happens because while you reading a file it will be taken as string and not as a list even if u kept the formatting of a list. thats why you getting [] while doing re.for line in read_in_fh: here you are taking each letters in the string thats why you are not getting the desired output. so iwrote something first to transform the string into a list. while doing that i also eliminated "" and '' as you mensioned. then wrote it in to a new file example.txt.
Note: change the file name according to your files
read_out_fh = open('file.txt',"r")
for line in read_out_fh:
line=line.strip("[]").replace('"','').replace("'",'').split(", ")
with open("example.txt", "w") as output:
for word in line:
#print(word)
output.write(word+'\n')
example.txt(outputfile)
blah.txt
blah1.txt
blah2.txt
The code below works out for your example you gave in the question:
# Content of textfile.txt:
asdasdasd=["'blah.txt'", "'blah1.txt'", "'blah2.txt'"]asdasdasd
# Code:
import re
read_in_fh = open('textfile.txt',"r")
write_out_fh = open('out_path.txt', "w")
for line in read_in_fh:
find_list = re.findall(r'\[(".*?"*)\]', line)
for element in find_list[0].split(","):
element_formatted = element.replace('"','').replace("'","").strip()
write_out_fh.write(element_formatted + "\n")
write_out_fh.close()
I am trying to pull a string of input names that get saved to a text file. I need to pull them by capital letter which is input. I.E. the saved text file contains names DanielDanClark, and I need to pull the names that begin with D. I am stuck at this part
for i in range(num):
print("Name",i+1," >> Enter the name:")
n=input("")
names+=n
file=open("names.txt","w")
file.write(names)
lookUp=input("Did you want to look up any names?(Y/N)")
x= ord(lookUp)
if x == 110 or x == 78:
quit()
else:
letter=input("Enter the first letter of the names you want to look up in uppercase:")
file=open("names.txt","r")
fileNames=[]
file.list()
for letter in file:
fileNames.index(letter)
fileNames.close()
I know that the last 4 lines are probably way wrong. It is what I tried in my last failed attempt
Lets break down your code block by block
num = 5
names = ""
for i in range(num)
print("Name",i+1," >> Enter the name:")
n=input("")
names+=n
I took the liberty of giving num a value of 5, and names a value of "", just so the code will run. This block has no problems. And will create a string called names with all the input taken. You might consider putting a delimiter in, which makes it more easier to read back your data. A suggestion would be to use \n which is a line break, so when you get to writing the file, you actually have one name on each line, example:
num = 5
names = ""
for i in range(num)
print("Name",i+1," >> Enter the name:")
n = input()
names += n + "\n"
Now you are going to write the file:
file=open("names.txt","w")
file.write(names)
In this block you forget to close the file, and a better way is to fully specify the pathname of the file, example:
file = open(r"c:\somedir\somesubdir\names.txt","w")
file.write(names)
file.close()
or even better using with:
with open(r"c:\somedir\somesubdir\names.txt","w") as openfile:
openfile.write(names)
The following block you are asking if the user want to lookup a name, and then exit:
lookUp=input("Did you want to look up any names?(Y/N)")
x= ord(lookUp)
if x == 110 or x == 78:
quit()
First thing is that you are using quit() which should not be used in production code, see answers here you really should use sys.exit() which means you need to import the sys module. You then proceed to get the numeric value of the answer being either N or n and you check this in a if statement. You do not have to do ord() you can use a string comparisson directly in your if statement. Example:
lookup = input("Did you want to look up any names?(Y/N)")
if lookup.lower() == "n":
sys.exit()
Then you proceed to lookup the requested data, in the else: block of previous if statement:
else:
letter=input("Enter the first letter of the names you want to look up in uppercase:")
file=open("names.txt","r")
fileNames=[]
file.list()
for letter in file:
fileNames.index(letter)
fileNames.close()
This is not really working properly either, so this is where the delimiter \n is coming in handy. When a text file is opened, you can use a for line in file block to enumerate through the file line by line, and with \n delimiter added in your first block, each line is a name. You also go wrong in the for letter in file block, it does not do what you think it should be doing. It actually returns each letter in the file, regardless of whay you type in the input earlier. Here is a working example:
letter = input("Enter the first letter of the names you want to look up in uppercase:")
result = []
with open(r"c:\somedir\somesubdir\names.txt", "r") as openfile:
for line in openfile: ## loop thru the file line by line
line = line.strip('\n') ## get rid of the delimiter
if line[0].lower() == letter.lower(): ## compare the first (zero) character of the line
result.append(line) ## append to result
print(result) ## do something with the result
Putting it all together:
import sys
num = 5
names = ""
for i in range(num)
print("Name",i+1," >> Enter the name:")
n = input("")
names += n + "\n"
with open(r"c:\somedir\somesubdir\names.txt","w") as openfile:
openfile.write(names)
lookup = input("Did you want to look up any names?(Y/N)")
if lookup.lower() == "n":
sys.exit()
letter = input("Enter the first letter of the names you want to look up in uppercase:")
result = []
with open(r"c:\somedir\somesubdir\names.txt", "r") as openfile:
for line in openfile:
line = line.strip('\n')
if line[0].lower() == letter.lower():
result.append(line)
print(result)
One caveat I like to point out, when you create the file, you open the file in w mode, which will create a new file every time, therefore overwriting the a previous file. If you like to append to a file, you need to open it in a mode, which will append to an existing file, or create a new file when the file does not exist.
Can you explain what is going on in this code? I don't seem to understand
how you can open the file and read it line by line instead of all of the sentences at the same time in a for loop. Thanks
Let's say I have these sentences in a document file:
cat:dog:mice
cat1:dog1:mice1
cat2:dog2:mice2
cat3:dog3:mice3
Here is the code:
from sys import argv
filename = input("Please enter the name of a file: ")
f = open(filename,'r')
d1ct = dict()
print("Number of times each animal visited each station:")
print("Animal Id Station 1 Station 2")
for line in f:
if '\n' == line[-1]:
line = line[:-1]
(AnimalId, Timestamp, StationId,) = line.split(':')
key = (AnimalId,StationId,)
if key not in d1ct:
d1ct[key] = 0
d1ct[key] += 1
The magic is at:
for line in f:
if '\n' == line[-1]:
line = line[:-1]
Python file objects are special in that they can be iterated over in a for loop. On each iteration, it retrieves the next line of the file. Because it includes the last character in the line, which could be a newline, it's often useful to check and remove the last character.
As Moshe wrote, open file objects can be iterated. Only, they are not of the file type in Python 3.x (as they were in Python 2.x). If the file object is opened in text mode, then the unit of iteration is one text line including the \n.
You can use line = line.rstrip() to remove the \n plus the trailing withespaces.
If you want to read the content of the file at once (into a multiline string), you can use content = f.read().
There is a minor bug in the code. The open file should always be closed. I means to use f.close() after the for loop. Or you can wrap the open to the newer with construct that will close the file for you -- I suggest to get used to the later approach.