I have a text file with all of them currently having the same end character (N), which is being used to identify progress the system makes. I want to change the end character to "Y" in case the program ends via an error or other interruptions so that upon restarting the program will search until a line has the end character "N" and begin working from there. Below is my code as well as a sample from the text file.
UPDATED CODE:
def GeoCode():
f = open("geocodeLongLat.txt", "a")
with open("CstoGC.txt",'r') as file:
print("Geocoding...")
new_lines = []
for line in file.readlines():
check = line.split('~')
print(check)
if 'N' in check[-1]:
geolocator = Nominatim()
dot_number, entry_name, PHY_STREET,PHY_CITY,PHY_STATE,PHY_ZIP = check[0],check[1],check[2],check[3],check[4],check[5]
address = PHY_STREET + " " + PHY_CITY + " " + PHY_STATE + " " + PHY_ZIP
f.write(dot_number + '\n')
try:
location = geolocator.geocode(address)
f.write(dot_number + "," + entry_name + "," + str(location.longitude) + "," + str(location.latitude) + "\n")
except AttributeError:
try:
address = PHY_CITY + " " + PHY_STATE + " " + PHY_ZIP
location = geolocator.geocode(address)
f.write(dot_number + "," + entry_name + "," + str(location.longitude) + "," + str(location.latitude) + "\n")
except AttributeError:
print("Cannot Geocode")
check[-1] = check[-1].replace('N','Y')
new_lines.append('~'.join(check))
with open('CstoGC.txt','r+') as file: # IMPORTANT to open as 'r+' mode as 'w/w+' will truncate your file!
for line in new_lines:
file.writelines(line)
f.close()
Output:
2967377~DARIN COLE~22112 TWP RD 209~ALVADA~OH~44802~Y
WAY 64 SUITE 100~EADS~TN~38028~N
384767~MILLER FARMS TRANS LLC~1103 COURT ST~BEDFORD~IA~50833~N
986150~R G S TRUCKING LTD~1765 LOMBARDIE DRIVE~QUESNEL~BC~V2J 4A8~N
1012987~DONALD LARRY KIVETT~4509 LANSBURY RD~GREENSBORO~NC~27406-4509~N
735308~ALZEY EXPRESS INC~2244 SOUTH GREEN STREET~HENDERSON~KY~42420~N
870337~RIES FARMS~1613 255TH AVENUE~EARLVILLE~IA~52057~N
148428~P R MASON & SON LLC~HWY 70 EAST~WILLISTON~NC~28589~N
220940~TEXAS MOVING CO INC~908 N BOWSER RD~RICHARDSON~TX~75081-2869~N
854042~ARMANDO ORTEGA~6590 CHERIMOYA AVENUE~FONTANA~CA~92337~N
940587~DIAMOND A TRUCKING INC~192285 E COUNTY ROAD 55~HARMON~OK~73832~N
1032455~INTEGRITY EXPRESS LLC~380 OLMSTEAD AVENUE~DEPEW~NY~14043~N
889931~DUNSON INC~33 CR 3581~FLORA VISTA~NM~87415~N
143608~LARRY A PETERSON & DONNA M PETERSON~W6359 450TH AVE~ELLSWORTH~WI~54011~N
635528~JAMES E WEBB~3926 GREEN ROAD~SPRINGFIELD~TN~37172~N
805496~WAYNE MLADY~22272 135TH ST~CRESCO~IA~52136~N
704996~SAVINA C MUNIZ~814 W LA QUINTA DR~PHARR~TX~78577~N
893169~BINDEWALD MAINTENANCE INC~213 CAMDEN DR~SLIDELL~LA~70459~N
948130~LOGISTICIZE LTD~861 E PERRY ST~PAULDING~OH~45879~N
438760~SMOOTH OPERATORS INC~W8861 CREEK ROAD~DARIEN~WI~53114~N
518872~A B C RELOCATION SERVICES INC~12 BOCKES ROAD~HUDSON~NH~03051~N
576143~E B D ENTERPRISES INC~29 ROY ROCHE DRIVE~WINNIPEG~MB~R3C 2E6~N
968264~BRIAN REDDEMANN~706 WESTGOR STREET~STORDEN~MN~56174-0220~N
721468~QUALITY LOGISTICS INC~645 LEONARD RD~DUNCAN~SC~29334~N
As you can see I am already keeping track of which line I am at just by using x. Should I use something like file.readlines()?
Sample of text document:
570772~CORPORATE BANK TRANSIT OF KENTUCKY INC~3157 HIGHWAY 64 SUITE 100~EADS~TN~38028~N
384767~MILLER FARMS TRANS LLC~1103 COURT ST~BEDFORD~IA~50833~N
986150~R G S TRUCKING LTD~1765 LOMBARDIE DRIVE~QUESNEL~BC~V2J 4A8~N
1012987~DONALD LARRY KIVETT~4509 LANSBURY RD~GREENSBORO~NC~27406-4509~N
735308~ALZEY EXPRESS INC~2244 SOUTH GREEN STREET~HENDERSON~KY~42420~N
870337~RIES FARMS~1613 255TH AVENUE~EARLVILLE~IA~52057~N
148428~P R MASON & SON LLC~HWY 70 EAST~WILLISTON~NC~28589~N
220940~TEXAS MOVING CO INC~908 N BOWSER RD~RICHARDSON~TX~75081-2869~N
854042~ARMANDO ORTEGA~6590 CHERIMOYA AVENUE~FONTANA~CA~92337~N
940587~DIAMOND A TRUCKING INC~192285 E COUNTY ROAD 55~HARMON~OK~73832~N
1032455~INTEGRITY EXPRESS LLC~380 OLMSTEAD AVENUE~DEPEW~NY~14043~N
889931~DUNSON INC~33 CR 3581~FLORA VISTA~NM~87415~N
Thank you!
Edit: updated code thanks to #idlehands
There are a few ways to do this.
Option #1
My original thought was to use the tell() and seek() method to go back a few steps but it quickly shows that you cannot do this conveniently when you're not opening the file in bytes and definitely not in a for loop of readlines(). You can see the reference threads here:
Is it possible to modify lines in a file in-place?
How to solve "OSError: telling position disabled by next() call"
The investigation led to this piece of code:
with open('file.txt','rb+') as file:
line = file.readline() # initiate the loop
while line: # continue while line is not None
print(line)
check = line.split(b'~')[-1]
if check.startswith(b'N'): # carriage return is expected for each line, strip it
# ... do stuff ... #
file.seek(-len(check), 1) # place the buffer at the check point
file.write(check.replace(b'N', b'Y')) # replace "N" with "Y"
line = file.readline() # read next line
In the first referenced thread one of the answers mentioned this could lead you to potential problems, and directly modifying the bytes on the buffer while reading it is probably considered a bad idea™. A lot of pros probably will scold me for even suggesting it.
Option #2a
(if file size is not horrendously huge)
with open('file.txt','r') as file:
new_lines = []
for line in file.readlines():
check = line.split('~')
if 'N' in check[-1]:
# ... do stuff ... #
check[-1] = check[-1].replace('N','Y')
new_lines.append('~'.join(check))
with open('file.txt','r+') as file: # IMPORTANT to open as 'r+' mode as 'w/w+' will truncate your file!
for line in new_lines:
file.writelines(line)
This approach loads all the lines into memory first, so you do the modification in memory but leave the buffer alone. Then you reload the file and write the lines that were changed. The caveat is that technically you are rewriting the entire file line by line - not just the string N even though it was the only thing changed.
Option #2b
Technically you could open the file as r+ mode from the onset and then after the iterations have completed do this (still within the with block but outside of the loop):
# ... new_lines.append('~'.join(check)) #
file.seek(0)
for line in new_lines:
file.writelines(line)
I'm not sure what distinguishes this from Option #1 since you're still reading and modifying the file in the same go. If someone more proficient in IO/buffer/memory management wants to chime in please do.
The disadvantage for Option 2a/b is that you always end up storing and rewriting the lines in the file even if you are only left with a few lines that needs to be updated from 'N' to 'Y'.
Results (for all solutions):
570772~CORPORATE BANK TRANSIT OF KENTUCKY INC~3157 HIGHWAY 64 SUITE 100~EADS~TN~38028~Y
384767~MILLER FARMS TRANS LLC~1103 COURT ST~BEDFORD~IA~50833~Y
986150~R G S TRUCKING LTD~1765 LOMBARDIE DRIVE~QUESNEL~BC~V2J 4A8~Y
1012987~DONALD LARRY KIVETT~4509 LANSBURY RD~GREENSBORO~NC~27406-4509~Y
735308~ALZEY EXPRESS INC~2244 SOUTH GREEN STREET~HENDERSON~KY~42420~Y
870337~RIES FARMS~1613 255TH AVENUE~EARLVILLE~IA~52057~Y
148428~P R MASON & SON LLC~HWY 70 EAST~WILLISTON~NC~28589~Y
220940~TEXAS MOVING CO INC~908 N BOWSER RD~RICHARDSON~TX~75081-2869~Y
854042~ARMANDO ORTEGA~6590 CHERIMOYA AVENUE~FONTANA~CA~92337~Y
940587~DIAMOND A TRUCKING INC~192285 E COUNTY ROAD 55~HARMON~OK~73832~Y
1032455~INTEGRITY EXPRESS LLC~380 OLMSTEAD AVENUE~DEPEW~NY~14043~Y
889931~DUNSON INC~33 CR 3581~FLORA VISTA~NM~87415~Y
And if you were to say, encountered a break at the line starting with 220940, the file would become:
570772~CORPORATE BANK TRANSIT OF KENTUCKY INC~3157 HIGHWAY 64 SUITE 100~EADS~TN~38028~Y
384767~MILLER FARMS TRANS LLC~1103 COURT ST~BEDFORD~IA~50833~Y
986150~R G S TRUCKING LTD~1765 LOMBARDIE DRIVE~QUESNEL~BC~V2J 4A8~Y
1012987~DONALD LARRY KIVETT~4509 LANSBURY RD~GREENSBORO~NC~27406-4509~Y
735308~ALZEY EXPRESS INC~2244 SOUTH GREEN STREET~HENDERSON~KY~42420~Y
870337~RIES FARMS~1613 255TH AVENUE~EARLVILLE~IA~52057~Y
148428~P R MASON & SON LLC~HWY 70 EAST~WILLISTON~NC~28589~Y
220940~TEXAS MOVING CO INC~908 N BOWSER RD~RICHARDSON~TX~75081-2869~N
854042~ARMANDO ORTEGA~6590 CHERIMOYA AVENUE~FONTANA~CA~92337~N
940587~DIAMOND A TRUCKING INC~192285 E COUNTY ROAD 55~HARMON~OK~73832~N
1032455~INTEGRITY EXPRESS LLC~380 OLMSTEAD AVENUE~DEPEW~NY~14043~N
889931~DUNSON INC~33 CR 3581~FLORA VISTA~NM~87415~N
There are pros and cons to these approaches. Try and see which one fits your use case the best.
I would read the entire input file into a list and .pop() the lines off one at a time. In case of an error, append the popped item to the list and write overwrite the input file. This way it will always be up to date and you won't need any other logic.
Related
question = "question:"
# QUESTION
f = open('dopeit.rtf', encoding="utf8", errors='ignore')
line = f.readline()
while line:
if question in line:
newline = line.replace('Question: ', '"')
print(newline + '"', end=",")
# use realine() to read next line
line = f.readline()
f.close()
the output is something like this
","Who directed Star Wars?
","Who was the only non Jedi in the original Star Wars trilogy to use a lightsaber?
","What kind of flower was enchanted and dying in Beauty and the Beast?
","Which is the longest movie ever made?
I want it to be like this:
"Who directed Star Wars?","Who was the only non Jedi in the original Star Wars trilogy to use a lightsaber?","What kind of flower was enchanted and dying in Beauty and the Beast?","Which is the longest movie ever made?
So how can I make these changes? I tried using the "end" command but it still seems to bring it to the next line? Am I doing something wrong???
newline = line.replace('Question: ', '"').replace("\n", "")
I am writing a Python program that reads a file and then writes its contents to another one, with added margins. The margins are user-input and the line length must be at most 80 characters.
I wrote a recursive function to handle this. For the most part, it is working. However, the 2 lines before any new paragraph display the indentation that was input for the right side, instead of keeping the left indentation.
Any clues on why this happen?
Here's the code:
left_Margin = 4
right_Margin = 5
# create variable to hold the number of characters to withhold from line_Size
avoid = right_Margin
num_chars = left_Margin
def insertNewlines(i, line_Size):
string_length = len(i) + avoid + right_Margin
if len(i) <= 80 + avoid + left_Margin:
return i.rjust(string_length)
else:
i = i.rjust(len(i)+left_Margin)
return i[:line_Size] + '\n' + ' ' * left_Margin + insertNewlines(i[line_Size:], line_Size)
with open("inputfile.txt", "r") as inputfile:
with open("outputfile.txt", "w") as outputfile:
for line in inputfile:
num_chars += len(line)
string_length = len(line) + left_Margin
line = line.rjust(string_length)
words = line.split()
# check if num of characters is enough
outputfile.write(insertNewlines(line, 80 - avoid - left_Margin))
For input of left_Margin=4 and right_Margin = 5, I expect this:
____Poetry is a form of literature that uses aesthetic and rhythmic
____qualities of language—such as phonaesthetics, sound symbolism, and
____metre—to evoke meanings in addition to, or in place of, the prosai
____c ostensible meaning.
____Poetry has a very long history, dating back to prehistorical ti
____mes with the creation of hunting poetry in Africa, and panegyric an
____d elegiac court poetry was developed extensively throughout the his
____tory of the empires of the Nile, Niger and Volta river valleys.
But The result is:
____Poetry is a form of literature that uses aesthetic and rhythmic
______qualities of language—such as phonaesthetics, sound symbolism, and
______metre—to evoke meanings in addition to, or in place of, the prosai
________c ostensible meaning.
_____Poetry has a very long history, dating back to prehistorical ti
_____mes with the creation of hunting poetry in Africa, and panegyric an
_____d elegiac court poetry was developed extensively throughout the his
_____tory of the empires of the Nile, Niger and Volta river valleys.
This isn't really a good fit for a recursive solution in Python. Below is an imperative/iterative solution of the formatting part of your question (I'm assuming you can take this and write it to a file instead). The code assumes that paragraphs are indicated by two consecutive newlines ('\n\n').
txt = """
Poetry is a form of literature that uses aesthetic and rhythmic qualities of language—such as phonaesthetics, sound symbolism, and metre—to evoke meanings in addition to, or in place of, the prosaic ostensible meaning.
Poetry has a very long history, dating back to prehistorical times with the creation of hunting poetry in Africa, and panegyric and elegiac court poetry was developed extensively throughout the history of the empires of the Nile, Niger and Volta river valleys.
"""
def format_paragraph(paragraph, length, left, right):
"""Format paragraph ``p`` so the line length is at most ``length``
with ``left`` as the number of characters for the left margin,
and similiarly for ``right``.
"""
words = paragraph.split()
lines = []
curline = ' ' * (left - 1) # we add a space before the first word
while words:
word = words.pop(0) # process the next word
# +1 in the next line is for the space.
if len(curline) + 1 + len(word) > length - right:
# line would have been too long, start a new line
lines.append(curline)
curline = ' ' * (left - 1)
curline += " " + word
lines.append(curline)
return '\n'.join(lines)
# we need to work on one paragraph at a time
paragraphs = txt.split('\n\n')
print('0123456789' * 8) # print a ruler..
for paragraph in paragraphs:
print(format_paragraph(paragraph, 80, left=4, right=5))
print() # next paragraph
the output of the above is:
01234567890123456789012345678901234567890123456789012345678901234567890123456789
Poetry is a form of literature that uses aesthetic and rhythmic
qualities of language such as phonaesthetics, sound symbolism, and
metre to evoke meanings in addition to, or in place of, the prosaic
ostensible meaning.
Poetry has a very long history, dating back to prehistorical times with
the creation of hunting poetry in Africa, and panegyric and elegiac
court poetry was developed extensively throughout the history of the
empires of the Nile, Niger and Volta river valleys.
So I need to write a program that reads a text file, and copies its contents to another file. I then have to add a column at the end of the text file, and populate that column with an int that is calculated using the function calc_bill. I can get it to copy the contents of the original file to the new one, but I cannot seem to get my program to read in the ints necessary for calc_bill to run.
Any help would be greatly appreciated.
Here are the first 3 lines of the text file I am reading from:
CustomerID Title FirstName MiddleName LastName Customer Type
1 Mr. Orlando N. Gee Residential 297780 302555
2 Mr. Keith NULL Harris Residential 274964 278126
It is copying the file exactly as it is supposed to to the new file. What is not working is writing the bill_amount (calc_bill)/ billVal(main) to the new file in a new column. Here is the expected output to the new file:
CustomerID Title FirstName MiddleName LastName Customer Type Company Name Start Reading End Reading BillVal
1 Mr. Orlando N. Gee Residential 297780 302555 some number
2 Mr. Keith NULL Harris Residential 274964 278126 some number
And here is my code:
def main():
file_in = open("water_supplies.txt", "r")
file_in.readline()
file_out = input("Please enter a file name for the output:")
output_file = open(file_out, 'w')
lines = file_in.readlines()
for line in lines:
lines = [line.split('\t')]
#output_file.write(str(lines)+ "\n")
billVal = 0
c_type = line[5]
start = int(line[7])
end = int(line[8])
billVal = calc_bill(c_type, start, end)
output_file.write(str(lines)+ "\t" + str(billVal) + "\n")
def calc_bill(customer_type, start_reading, end_reading):
price_per_gallon = 0
if customer_type == "Residential":
price_per_gallon = .012
elif customer_type == "Commercial":
price_per_gallon = .011
elif customer_type == "Industrial":
price_per_gallon = .01
if start_reading >= end_reading:
print("Error: please try again")
else:
reading = end_reading - start_reading
bill_amount = reading * price_per_gallon
return bill_amount
main()
There are the issues mentioned above, but here is a small change to your main() method that works correctly.
def main():
file_in = open("water_supplies.txt", "r")
# skip the headers in the input file, and save for output
headers = file_in.readline()
# changed to raw_input to not require quotes
file_out = raw_input("Please enter a file name for the output: ")
output_file = open(file_out, 'w')
# write the headers back into output file
output_file.write(headers)
lines = file_in.readlines()
for line in lines:
# renamed variable here to split
split = line.split('\t')
bill_val = 0
c_type = split[5]
start = int(split[6])
end = int(split[7])
bill_val = calc_bill(c_type, start, end)
# line is already a string, don't need to cast it
# added rstrip() to remove trailing newline
output_file.write(line.rstrip() + "\t" + str(bill_val) + "\n")
Note that the line variable in your loop includes the trailing newline, so you will need to strip that off as well if you're going to write it to the output file as-is. Your start and end indices were off by 1 as well, so I changed to split[6] and split[7].
It is a good idea to not require the user to include the quotes for the filename, so keep that in mind as well. An easy way is to just use raw_input instead of input.
Sample input file (from OP):
CustomerID Title FirstName MiddleName LastName Customer Type
1 Mr. Orlando N. Gee Residential 297780 302555
2 Mr. Keith NULL Harris Residential 274964 278126
$ python test.py
Please enter a file name for the output:test.out
Output (test.out):
1 Mr. Orlando N. Gee Residential 297780 302555 57.3
2 Mr. Keith NULL Harris Residential 274964 278126 37.944
There are a couple things. The inconsistent spacing in your column names makes counting the actual columns a bit confusing, but I believe there are 9 column names there. However, each of your rows of data have only 8 elements, so it looks like you've got an extra column name (maybe "CompanyName"). So get rid of that, or fix the data.
Then your "start" and "end" variables are pointing to indexes 7 and 8, respectively. However, since there are only 8 elements in the row, I think the indexes should be 6 and 7.
Another problem could be that inside your for-loop through "lines", you set "lines" to the elements in that line. I would suggest renaming the second "lines" variable inside the for-loop to something else, like "elements".
Aside from that, I'd just caution you about naming consistency. Some of your column names are camel-case and others have spaces. Some of your variables are separated by underscores and others are camel-case.
Hopefully that helps. Let me know if you have any other questions.
You have two errors in handling your variables, both in the same line:
lines = [line.split()]
You put this into your lines variable, which is the entire file contents. You just lost the rest of your input data.
You made a new list-of-list from the return of split.
Try this line:
line = line.split()
I got reasonable output with that change, once I make a couple of assumptions about your placement of tabs.
Also, consider not overwriting a variable with a different data semantic; it confuses the usage. For instance:
for record in lines:
line = record.split()
The problem is: I have a data set to clean. I am currently using Python 3.6 as intrepreter in PyCharm(community edition) to work on this.
I need to:
Find a line where the word "Code" appears and
paste all the following lines in a single line together until
the next word "Code" comes
This is would essentially break the data into 2 fields ,namely; Code and details of the company.
The final output needs to be in a table in a text file or csv written through Pycharm itself and this format is critical.
The following is the input(extract from actual textfile) :
345- Code # 98882 +
"Ms, ABDUL RAFAY & COMPANY, +"
"907, 2nd Floor, tradeway Centre,33, Block-6, PECHS, Karach +"
Ph:345598 1334 558106 +
Mr. Abdul rafay Siddiqui +
347 Code # 96663 +
"Ms. BILAL & BROTHERS Plot No.F-8, Estate #2, Lalazar, Karachi Ph:322575.84 +"
Mr. Mubarak Shahid +
A23 - Code : BO229 +
"Ms. RAHMAN & SONS 303, 3rd Floor, Square One, Dundas street, Karachi P:36268947 +"
"Mr, Saleem Mughal +"
"349- Code # 93369 Ms, ALIAPPAREL +"
"Office No. 491/307, 1st Floor, Blessings Tower near Tipu Burger , P?:34990456 +"
"Mr, Nasir Wali +"
The output should be like this :
Code - Company details
345- Code # 98882 + -"Ms, ABDUL RAFAY & COMPANY, +""907, 2nd Floor, tradeway Centre,33, Block-6, PECHS, Karach +"Ph:345598 1334 558106 +Mr. Abdul rafay Siddiqui +
347 Code # 96663 + - "Ms. BILAL & BROTHERS Plot No.F-8, Estate #2, Lalazar, Karachi Ph:322575.84 +"Mr. Mubarak Shahid +
The key to the data is that the company details are sometimes in one line or two or three .So if there could be a way to iterate over these till the next 'Code' appears. I had tried this before in R but couldnt come up with anything concrete excepting adding + which could be stripped off here.
All you need to do is iterate through the file, looking for a line that signals the start of a new data block.
This does more or less what you want:
def emit(lines, dest):
if lines:
print("".join(lines), file=dest)
company_data = []
with open('details.txt') as data_in, open('fixed_details','w') as data_out:
for line in data_in:
if "Code " in line: # start of a new company: output the previous one
emit(company_data, data_out)
company_data = []
company_data.append (line.strip())
emit(company_data, data_out)
It doesn't do exactly what you want because your sample output sometimes specifies a hyphen between the company code and the rest of the data, and sometimes a hyphen and a space.
345- Code # 98882 + -"Ms, ABDUL RAFAY ...(etc)
347 Code # 96663 + - "Ms. BILAL & BROTHERS ...(etc)
^ this is the space
In line 345 there is no space but in line 347 there is. There is no corresponding space in your sample input data so it isn't clear what you want the program to do. I just left the hyphen out. I'll leave sorting that out (and supplying the headings) up to you. You will probably want to change the print() call to distinguish between the first line of data and the rest:
print(lines[0], "-", "".join(lines[1:]), file=dest)
This is the output:
345- Code # 98882 +"Ms, ABDUL RAFAY & COMPANY, +""907, 2nd Floor, tradeway Centre,33, Block-6, PECHS, Karach +"Ph:345598 1334 558106 +Mr. Abdul rafay Siddiqui +
347 Code # 96663 +"Ms. BILAL & BROTHERS Plot No.F-8, Estate #2, Lalazar, Karachi Ph:322575.84 +"Mr. Mubarak Shahid +
A23 - Code : BO229 +"Ms. RAHMAN & SONS 303, 3rd Floor, Square One, Dundas street, Karachi P:36268947 +""Mr, Saleem Mughal +"
"349- Code # 93369 Ms, ALIAPPAREL +""Office No. 491/307, 1st Floor, Blessings Tower near Tipu Burger , P?:34990456 +""Mr, Nasir Wali +"
this is my code:
>>> p = open(r'/Users/ericxx/Desktop/dest.txt','r+')
>>> xx = p.read()
>>> xx = xx[:0]+"How many roads must a man walk down\nBefore they call him a man" +xx[0:]
>>> p.writelines(xx)
>>> p.close()
the original file content looks like:
How many seas must a white dove sail
Before she sleeps in the sand
the result looks like :
How many seas must a white dove sail
Before she sleeps in the sand
How many roads must a man walk down
Before they call him a man
How many seas must a white dove sail
Before she sleeps in the sand
expected output :
How many roads must a man walk down
Before they call him a man
How many seas must a white dove sail
Before she sleeps in the sand
You have to "rewind" the file between reading and writing:
p.seek(0)
The whole code will look like this (with other minor changes):
p = open('/Users/ericxx/Desktop/dest.txt','r+')
xx = p.read()
xx = "How many roads must a man walk down\nBefore they call him a man" + xx
p.seek(0)
p.write(xx)
p.close()
Adding to #messas answer,
while doing seek to add the data in the front it can also leave you with old data at the end of your file if you ever shortened xx at any point.
This is because p.seek(0) puts the input pointer in the file at the beginning of the file and any .write() operation will overwrite content as it goes. However a shorter content written vs content already in the file will result in som old data being left at the end, not overwritten.
To avoid this you could open and close the file twice with , 'w') as the opening parameter the second time around or store/fetch the file contents length and pad your new content. Or truncate the file to your new desired length.
To truncate the file, simply add p.flush() after you've written the data.
Also, use the with operator
with open('/Users/ericxx/Desktop/dest.txt','r+') as p:
xx = p.read()
xx = "How many roads must a man walk down\nBefore they call him a man" + xx
p.seek(0)
p.write(xx)
p.flush()
I'm on my phone so apologies if the explanation is some what short and blunt and lacking code. Can update more tomorrow.