I am trying to save and read the strings which are saved in a text file.
a = [['str1','str2','str3'],['str4','str5','str6'],['str7','str8','str9']]
file = 'D:\\Trails\\test.txt'
# writing list to txt file
thefile = open(file,'w')
for item in a:
thefile.write("%s\n" % item)
thefile.close()
#reading list from txt file
readfile = open(file,'r')
data = readfile.readlines()#
print(a[0][0])
print(data[0][1]) # display data read
the output:
str1
'
both a[0][0] and data[0][0] should have the same value, reading which i saved returns empty. What is the mistake in saving the file?
Update:
the 'a' array is having strings on different lengths. what are changes that I can make in saving the file, so that output will be the same.
Update:
I have made changes by saving the file in csv instead of text using this link, incase of text how to save the data ?
You can save the list directly on file and use the eval function to translate the saved data on file in list again. Isn't recommendable but, the follow code works.
a = [['str1','str2','str3'],['str4','str5','str6'],['str7','str8','str9']]
file = 'test.txt'
# writing list to txt file
thefile = open(file,'w')
thefile.write("%s" % a)
thefile.close()
#reading list from txt file
readfile = open(file,'r')
data = eval(readfile.readline())
print(data)
print(a[0][0])
print(data[0][1]) # display data read
print(a)
print(data)
a and data will not have same value as a is a list of three lists.
Whereas data is a list with three strings.
readfile.readlines() or list(readfile) writes all lines in a list.
So, when you perform data = readfile.readlines() python consider ['str1','str2','str3']\n as a single string and not as a list.
So,to get your desired output you can use following print statement.
print(data[0][2:6])
Related
I am a little bit confused in how to read all lines in many files where the file names have format from "datalog.txt.98" to "datalog.txt.120".
This is my code:
import json
file = "datalog.txt."
i = 97
for line in file:
i+=1
f = open (line + str (i),'r')
for row in f:
print (row)
Here, you will find an example of one line in one of those files:
I need really to your help
I suggest using a loop for opening multiple files with different formats.
To better understand this project I would recommend researching the following topics
for loops,
String manipulation,
Opening a file and reading its content,
List manipulation,
String parsing.
This is one of my favourite beginner guides.
To set the parameters of the integers at the end of the file name I would look into python for loops.
I think this is what you are trying to do
# create a list to store all your file content
files_content = []
# the prefix is of type string
filename_prefix = "datalog.txt."
# loop from 0 to 13
for i in range(0,14):
# make the filename variable with the prefix and
# the integer i which you need to convert to a string type
filename = filename_prefix + str(i)
# open the file read all the lines to a variable
with open(filename) as f:
content = f.readlines()
# append the file content to the files_content list
files_content.append(content)
To get rid of white space from file parsing add the missing line
content = [x.strip() for x in content]
files_content.append(content)
Here's an example of printing out files_content
for file in files_content:
print(file)
I am reading a text file and I want to read a list of tuples so that I can add another tuple to it in my program and write that appended tuple back to the text file.
Example in the file
[('john', 'abc')]
Want to write back to the file as
[('john', 'abc'), ('jack', 'def')]
However, I whenever I keep writing back to the file, the appended tuple seems to add in double quotes along with square brackets. I just want it to appear as above.
You can write a reusable function which takes 2 parameters file_path (on which you want to write tuple), tup (which you want to append) and put your logic inside that. Later you can supply proper data to this function and it will do the job for you.
Note: Don't forget to read the documentation as comments in code
tuples.txt (Before writing)
[('john', 'abc')]
Code
def add_tuple_to_file(file_path, tup):
with open(file_path, 'r+') as f:
content = f.read().strip() # read content from file and remove whitespaces around
tuples = eval(content) # convert string format tuple to original tuple object (not possible using json.loads())
tuples.append(tup) # append new tuple `tup` to the old list
f.seek(0) # After reading file, file pointer reaches to end of file so place it again at beginning
f.truncate() # truncate file (erase old content)
f.write(str(tuples)) # write back the updated list
# Try
add_tuple_to_file("./tuples.txt", ('jack', 'def'))
tuples.txt (After writing back)
[('john', 'abc'), ('jack', 'def')]
References
https://www.geeksforgeeks.org/python-ways-to-convert-string-to-json-object/
How to open a file for both reading and writing?
You can use ast.literal_eval to get the list object from the string.
import ast
s = "[('john', 'abc')]"
o = ast.literal_eval(s)
print(repr(o)==s)
o.append(('jack', 'def'))
newstr = repr(o)
print(newstr)
Here it is in action.
I am trying to get some data from a website (using the modules named requests & BeautifulSoup) and print it in a text file but every time I try to do so, it says the following:
TypeError: descriptor 'write' requires a 'file' object but received a 'NavigableString'
I have tried using the csv library to import the data but since I couldn't add the line by line data to the csv, I decided to add all the output to a text file and then take out the data I require.
file_object = open("name-list.txt", "w") #Opening the file
name = soup.find(class_='table-responsive') #Extracting the data
name_list = name.find_all('td') #Refining the data
for final in name_list:
all = final.contents[0] #Final result
file.write(all) #This is where the Error Comes
file.close()
When I use print(all) in the for loop, I get the output that I need which consists of multi-line text including the names, age, gender, etc. of the people from the table on the website but when I try to print that output into the text file, the error pops up.
I have a csv file which contains data in two columns, as follows:
40500 38921
43782 32768
55136 49651
63451 60669
50550 36700
61651 34321
and so on...
I want to convert each data into it's hex equivalent, then concatenate them, and write them into a column in another csv file.
For example: hex(40500) = 9E34, and hex(38921) = 9809.
So, in output csv file, element A1 would be 9E349809
So, i am expecting column A in output csv file to be:
9E349809
AB068000
D760C1F3
F7DBECFD
C5768F5C
F0D38611
I referred a sample code which concatenates two columns, but am struggling with the converting them to hex and then concatenating them. Following is the code:-
import csv
inputFile = 'input.csv'
outputFile = 'output.csv'
with open(inputFile) as f:
reader = csv.reader(f)
with open(outputFile, 'w') as g:
writer = csv.writer(g)
for row in reader:
new_row = [''.join([row[0], row[1]])] + row[2:]
writer.writerow(new_row)
How can i convert data in each column to its hex equivalent, then concatenate them and write them in another file?
You could do this in 4 steps:
Read the lines from the input csv file
Use formatting options to get the hex values of each number
Perform string concatenation to get your result
Write to new csv file.
Sample Code:
with open (outputFile, 'w') as outfile:
with open (inputFile,'r') as infile:
for line in infile: # Iterate through each line
left, right = int(line.split()[0]), int(line.split()[1]) # split left and right blocks
newstr = '{:x}'.format(left)+'{:x}'.format(right) # create new string using hex values excluding '0x'
outfile.write(newstr) # write to output file
print ('Conversion completed')
print ('Closing outputfile')
Sample Output:
In[44] line = '40500 38921'
Out[50]: '9e349809'
ParvBanks solution is good (clear and functionnal), I would simplify it a little like that:
with open (inputFile,'r') as infile, open (outputFile, 'w+') as outfile:
for line in infile:
outfile.write("".join(["{:x}".format(int(v)) for v in line.split()]))
I have 4 lists called I_list, Itiso, ItHDKR and Itperez and I would like to receive .txt output files with the data of these lists. I am trying to make Python rename automatically the name of the .txt output files in terms of some of my input data. In this way, the .txt output files will always have different names.
Now I am programming the following commands:
Horizontal_radiation = []
Isotropic_radiation = []
HDKR_radiation = []
Perez_radiation = []
Horizontal = open("outputHorizontal.txt", 'w')
Isotropic = open("outputIsotropic.txt", 'w')
HDKR = open("outputHDKR.txt", 'w')
Perez = open("outputPerez.txt", 'w')
for i in I_list:
Horizontal_radiation.append(i)
for x in Itiso:
Isotropic_radiation.append(x)
for y in ItHDKR:
HDKR_radiation.append(y)
for z in Itperez:
Perez_radiation.append(z)
Horizontal.write(str(Horizontal_radiation))
Isotropic.write(str(Isotropic_radiation))
HDKR.write(str(HDKR_radiation))
Perez.write(str(Perez_radiation))
Horizontal.close()
Isotropic.close()
HDKR.close()
Perez.close()
As you can see, the name of the .txt output file is fixed as "outputHorizontal.txt" (the first one). Is there any way to change this name and put it according to a input? For example, one of my inputs is the latitude, as 'lat'. I am trying to make the output file name be expressed in terms of 'lat', in this way everytime I run the program the name would be different, because now I always get the same name and the file is overwritten.
Thank you very much people, kind regards.
You can pass a string variable as the output file name. For example you could move the file declarations after you add elements to the lists (and before you write them) and use
Horizontal = open(str(Horizontal_radiation[0]), 'w')
Or just add a timestamp to the file name if it's all about don't overwriting files
Horizontal = open("horizontal-%s".format(datetime.today()), 'w')