Develop Reference

If the csv file is more than 3 lines, edit it to delete the first line (Not save as new file)

Im trying to code if the csv file is more than 3 lines, edit it to delete the first line.
I want to delete the first line from the existing file instead of saving it as a new file.
For this reason, I had to delete the existing file and create a file with the same name but
only one line is saved and the comma disappears.
I'm using Pandas data frame. But if it doesn't matter if I don't use it, I don't want to use it
Function name might be weird because I'm a beginner
Thanks.
file = open("./csv/selllist.csv", encoding="ANSI")
reader = csv.reader(file)
lines= len(list(reader))
if lines > 3:
df = pd.read_csv('./csv/selllist.csv', 'r+', encoding="ANSI")
dfa = df.iloc[1:]
print(dfa)
with open("./csv/selllist.csv", 'r+', encoding="ANSI") as x:
x.truncate(0)
with open('./csv/selllist.csv', 'a', encoding="ANSI", newline='') as fo:
# Pass the CSV file object to the writer() function
wo = writer(fo)
# Result - a writer object
# Pass the data in the list as an argument into the writerow() function
wo.writerow(dfa)
# Close the file object
fo.close()
print()
This is the type of csv file I deal with
string, string, string, string, string
string, string, string, string, string
string, string, string, string, string
string, string, string, string, string

Take a 2-step approach.
Open the file for reading and count the number of lines. If there are more than 3 lines, re-open the file (for writing) and update it.
For example:
lines = []
with open('./csv/selllist.csv') as csv:
lines = csv.readlines()
if len(lines) > 3:
with open('./csv/selllist.csv', 'w') as csv:
for line in lines[1:]: # skip first line
csv.write(line)

With pandas, you can just specify header=None while reading and writing:
import pandas as pd
if lines > 3:
df = pd.read_csv("data.csv", header=None)
df.iloc[1:].to_csv("data.csv", header=None, index=None)
With the csv module:
import csv
with open("data.csv") as infile:
reader = csv.reader(infile)
lines = list(reader)
if len(lines)>3:
with open("data.csv", "w", newline="") as outfile:
writer = csv.writer(outfile, delimiter=",")
writer.writerows(lines[1:])

With one open call and using seek and truncate.
Setup
out = """\
Look at me
I'm a file
for sure
4th line, woot!"""
with open('filepath.csv', 'w') as fh:
fh.write(out)
Solution
I'm aiming to minimize the stuff I'm doing. I'll only open one file and only one time. I'll only split one time.
with open('filepath.csv', 'r+') as csv:
top, rest = csv.read().split('\n', 1) # Only necessary to pop off first line
if rest.count('\n') > 1: # If 4 or more lines, there will be at
# least two more newline characters
csv.seek(0) # Once we're done reading, we need to
# go back to beginning of file
csv.truncate() # truncate to reduce size of file as well
csv.write(rest)

Data Formatting within a txt. File

I have the following txt file that needs to be formatted with specific start and end positions for data throughout the file. For instance, column 1 is blank and will be read as an entry number. The values for this data type is a numeric 9 and should have the following positions (1-9). Next is employee ID with positions (10-15).. and so on. Values do not need a delimiter.
,MB4858,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225D,,,DF2016,CA4310,,0172CA,,,,,Y,
,MD6535,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225D,,,DF2016,CA4310,,0172CA,,,,,Y,
,PM7858,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225D,,,DF2016,CA4310,,0172CA,,,,,Y,
,RM0111,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225D,,,DF2016,CA4310,,0172CA,,,,,Y,
,RY2585,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225D,,,DF2016,CA4310,,0172CA,,,,,Y,
,TM0617 ,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225D,,,DF2016,CA4310,,0172CA,,,,,Y,
,VE2495,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225D,,,DF2016,CA4310,,0172CA,,,,,Y,
,VJ8913,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225D,,,DF2016,CA4310,,0172CA,,,,,Y,
,FJ4815 ,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225D,,,DF2016,CA4310,,0172CA,,,,,Y,
,OM0188,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225D,,,DF2016,CA4310,,0172CA,,,,,Y,
,H00858,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,
,H08392,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,
,H15624,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,
,H27573,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,
,H40249,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,
,H44581,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,
,H48473,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,
,H51570,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,
,H55768,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,
,H64315,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,
,H71507,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,
,H72248,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,
,H78527,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,
,H90393,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,
,H95973,01,1,CA,07/18/20,0,0,4.8,,,,,,14.77,,Y,2225DH,,,DF2016,CA4311,,0172CA,,,,,Y,

You can try starting here:
import sys
inFile = sys.argv[1]
outFile = "newFile.txt"
with open(inFile, 'r') as inf, open(outFile, 'w') as outf:
for line in inf:
line = line.split(',')
print(line)
Where sys argv[1] is the name of your txt file when you run the python script from the command line.
You can see that it will print out a list containing individual strings between the comma delimiters you have in your txt data file. From there you can do list manipulations to format the data. And then write it to outf like so (example):
# do what ever manipulations here to the output line
output_line = line[0] + " " + line[1]
outf.write(output_line)
outf.write('\n'

Split String in Text File to Multiple Rows in Python

I have a string within a text file that reads as one row, but I need to split the string into multiple rows based on a separator. If possible, I would like to separate the elements in the string based on the period (.) separating the different line elements listed here:
"Line 1: Element '{URL1}Decimal': 'x' is not a valid value of the atomic type 'xs:decimal'.Line 2: Element '{URL2}pos': 'y' is not a valid value of the atomic type 'xs:double'.Line 3: Element '{URL3}pos': 'y z' is not a valid value of the list type '{list1}doubleList'"
Here is my current script that is able to read the .txt file and convert it to a csv, but does not separate each entry into it's own row.
import glob
import csv
import os
path = "C:\\Users\\mdl518\\Desktop\\txt_strip\\"
with open(os.path.join(path,"test.txt"), 'r') as infile, open(os.path.join(path,"test.csv"), 'w') as outfile:
stripped = (line.strip() for line in infile)
lines = (line.split(",") for line in stripped if line)
writer = csv.writer(outfile)
writer.writerows(lines)
If possible, I would like to be able to just write to a .txt with multiple rows but a .csv would also work - Any help is most appreciated!

One way to make it work:
import glob
import csv
import os
path = "C:\\Users\\mdl518\\Desktop\\txt_strip\\"
with open(os.path.join(path,"test.txt"), 'r') as infile, open(os.path.join(path,"test.csv"), 'w') as outfile:
stripped = (line.strip() for line in infile)
lines = ([sent] for para in (line.split(".") for line in stripped if line) for sent in para)
writer = csv.writer(outfile)
writer.writerows(lines)
Explanation below:
The output is one line because code in the last line reads a 2d array and there is only one instance in that 2d array which is the entire paragraph. To visualise it, "lines" is stored as [[s1,s2,s3]] where writer.writerows() takes rows input as [[s1],[s2],[s3]]
There can be two improvements.
(1) Take period '.' as seperator. line.split(".")
(2) Iterate over the split list in the list comprehension.
lines = ([sent] for para in (line.split(".") for line in stripped if line) for sent in para)
str.split() splits a string by separator and store instances in a list. In your case, it tried to store the list in a list comprehension which made it a 2d array. It saves your paragraph into [[s1,s2,s3]]

How do I split each line into two strings and print without the comma?

I'm trying to have output to be without commas, and separate each line into two strings and print them.
My code so far yields:
173,70
134,63
122,61
140,68
201,75
222,78
183,71
144,69
But i'd like it to print it out without the comma and the values on each line separated as strings.
if __name__ == '__main__':
# Complete main section of code
file_name = "data.txt"
# Open the file for reading here
my_file = open('data.txt')
lines = my_file.read()
with open('data.txt') as f:
for line in f:
lines.split()
lines.replace(',', ' ')
print(lines)

In your sample code, line contains the full content of the file as a str.
my_file = open('data.txt')
lines = my_file.read()
You then later re-open the file to iterate the lines:
with open('data.txt') as f:
for line in f:
lines.split()
lines.replace(',', ' ')
Note, however, str.split and str.replace do not modify the existing value, as strs in python are immutable. Also note you are operating on lines there, rather than the for-loop variable line.
Instead, you'll need to assign the result of those functions into new values, or give them as arguments (E.g., to print). So you'll want to open the file, iterate over the lines and print the value with the "," replaced with a " ":
with open("data.txt") as f:
for line in f:
print(line.replace(",", " "))
Or, since you are operating on the whole file anyway:
with open("data.txt") as f:
print(f.read().replace(",", " "))
Or, as your file appears to be CSV content, you may wish to use the csv module from the standard library instead:
import csv
with open("data.txt", newline="") as csvfile:
for row in csv.reader(csvfile):
print(*row)

with open('data.txt', 'r') as f:
for line in f:
for value in line.split(','):
print(value)

while python can offer us several ways to open files this is the prefered one for working with files. becuase we are opening the file in lazy mode (this is the prefered one espicialy for large files), and after exiting the with scope (identation block) the file io will be closed automaticly by the system.
here we are openening the file in read mode. files folow the iterator polices, so we can iterrate over them like lists. each line is a true line in the file and is a string type.
After getting the line, in line variable, we split (see str.split()) the line into 2 tokens, one before the comma and the other after the comma. split return new constructed list of strings. if you need to omit some unwanted characters you can use the str.strip() method. usualy strip and split combined together.
elegant and efficient file reading - method 1
with open("data.txt", 'r') as io:
for line in io:
sl=io.split(',') # now sl is a list of strings.
print("{} {}".format(sl[0],sl[1])) #now we use the format, for printing the results on the screen.
non elegant, but efficient file reading - method 2
fp = open("data.txt", 'r')
line = None
while (line=fp.readline()) != '': #when line become empty string, EOF have been reached. the end of file!
sl=line.split(',')
print("{} {}".format(sl[0],sl[1]))

Python - rearrange and write strings (line splitting, unwanted newline)

I have a script that:
Reads in each line of a file
Finds the '*' character in each line and splits the line here
Rearranges the 3 parts (first to last, and last to first)
Writes the rearranged strings to a .txt file
Problem is, it's finding some new line character or something, and isn't outputting how it should. Have tried stripping newline chars, but there must be something I'm missing.
Thanks in advance for any help!
the script:
## Import packages
import time
import csv
## Make output file
file_output = open('output.txt', 'w')
## Open file and iterate over, rearranging the order of each string
with open('input.csv', 'rb') as f:
## Jump to next line (skips file headers)
next(f)
## Split each line, rearrange, and write the new line
for line in f:
## Strip newline chars
line = line.strip('\n')
## Split original string
category, star, value = line.rpartition("*")
##Make new string
new_string = value+star+category+'\n'
## Write new string to file
file_output.write(new_string)
file_output.close()
## Require input (stops program from immediately quitting)
k = input(" press any key to exit")
Input file (input.csv):
Category*Hash Value
1*FB1124FF6D2D4CD8FECE39B2459ED9D5
1*FB1124FF6D2D4CD8FECE39B2459ED9D5
1*FB1124FF6D2D4CD8FECE39B2459ED9D5
1*34AC061CCCAD7B9D70E8EF286CA2F1EA
Output file (output.txt)
FB1124FF6D2D4CD8FECE39B2459ED9D5
*1
FB1124FF6D2D4CD8FECE39B2459ED9D5
*1
FB1124FF6D2D4CD8FECE39B2459ED9D5
*1
34AC061CCCAD7B9D70E8EF286CA2F1EA
*1
EDIT: Answered. Thanks everyone! Looks all good now! :)

The file output.txt should exist.
The following work with python2 on debian:
## Import packages
import time
import csv
## Make output file
file_output = open('output.txt', 'w')
## Open file and iterate over, rearranging the order of each string
with open('input.csv', 'rb') as f:
## Jump to next line (skips file headers)
next(f)
## Split each line, rearrange, and write the new line
for line in f:
## Split original string
category, star, value = line.rpartition("*")
##Make new string
new_string = value.strip()+star+category+'\n'
## Write new string to file
file_output.write(new_string)
file_output.close()
## Require input (stops program from immediately quitting)
k = input(" press any key to exit")
I strip() the value witch contain the \n in order to sanitize it. You used strip('\n') which could be ambiguous and just using the method without parameter do the job.

Use a DictWriter
import csv
with open('aster.csv') as f, open('out.txt', 'w') as fout:
reader = csv.DictReader(f, delimiter='*')
writer = csv.DictWriter(fout, delimiter='*', fieldnames=['Hash Value','Category'])
#writer.writeheader()
for line in reader:
writer.writerow(line)
Without csv library
with open('aster.csv') as f:
next(f)
lines = [line.strip().split('*') for line in f]
with open('out2.txt', 'w') as fout:
for line in lines:
fout.write('%s*%s\n' % (line[1], line[0]))