I am downloading csv file and then reading it using csv module. For some reason, words and numbers get tokenized into letters and single digits. However, there is exception with "1 Mo", "3 Mo" etc.
I am getting csv file from here:
url = https://home.treasury.gov/resource-center/data-chart-center/interest-rates/daily-treasury-rates.csv/2022/all?type=daily_treasury_yield_curve&field_tdr_date_value=2022&page&_format=csv
I use Python 3.10 and the code looks as follows:
from urllib.request import urlopen
import csv
response = urlopen(url)
content = response.read().decode('utf-8')
csv_data = csv.reader(content, delimiter=',')
for row in csv_data:
print(row)
Here is what I am getting:
['D']
['a']
['t']
['e']
['','']
['1 Mo']
['','']
['2 Mo']
['','']
['3 Mo']
['','']
.
.
.
['30 Yr']
[]
['1']
['1']
['/']
['0']
['8']
['/']
.
.
.
I tried different delimiters but it does not help.
P.S. When I simply save csv file to drive and then open it - everything works properly. But I don't want to have this extra step.
Check out the documentation for csv.reader at this link:
csv.reader(csvfile, dialect='excel', **fmtparams)
...csvfile can be any object which supports the iterator protocol and returns a string each time its __next__() method is called -- file objects and list objects are both suitable...
Notice that your variable content is a string, not a file. In Python, strings may be iterators, but their __next__() method does not return the next line. You probably want to convert your long CSV string into a list of lines, so that __next__() (when it is called internally to the reader function) will give the next line instead of the next character. Note that this is why your code mysteriously works when you save the CSV to a file first - an open file iterator returns the next line of input each time __next__() is invoked.
To accomplish this, try using the following line in place of line 4:
content = response.read().decode('utf-8').split("\n")
Related
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 have used tweepy to store the text of tweets in a csv file using Python csv.writer(), but I had to encode the text in utf-8 before storing, otherwise tweepy throws a weird error.
Now, the text data is stored like this:
"b'Lorem Ipsum\xc2\xa0Assignment '"
I tried to decode this using this code (there is more data in other columns, text is in 3rd column):
with open('data.csv','rt',encoding='utf-8') as f:
reader = csv.reader(f,delimiter=',')
for row in reader:
print(row[3])
But, it doesn't decode the text. I cannot use .decode('utf-8') as the csv reader reads data as strings i.e. type(row[3]) is 'str' and I can't seem to convert it into bytes, the data gets encoded once more!
How can I decode the text data?
Edit: Here's a sample line from the csv file:
67783591545656656999,3415844,1450443669.0,b'Virginia School District Closes After Backlash Over Arabic Assignment: The Augusta County school district in\xe2\x80\xa6 | #abcde',52,18
Note: If the solution is in the encoding process, please note that I cannot afford to download the entire data again.
The easiest way is as below. Try it out.
import csv
from io import StringIO
byte_content = b"iam byte content"
content = byte_content.decode()
file = StringIO(content)
csv_data = csv.reader(file, delimiter=",")
If your input file really contains strings with Python syntax b prefixes on them, one way to workaround it (even though it's not really a valid format for csv data to contain) would be to use Python's ast.literal_eval() function as #Ry suggested — although I would use it in a slightly different manner, as shown below.
This will provide a safe way to parse strings in the file which are prefixed with a b indicating they are byte-strings. The rest will be passed through unchanged.
Note that this doesn't require reading the entire CSV file into memory.
import ast
import csv
def _parse_bytes(field):
"""Convert string represented in Python byte-string literal b'' syntax into
a decoded character string - otherwise return it unchanged.
"""
result = field
try:
result = ast.literal_eval(field)
finally:
return result.decode() if isinstance(result, bytes) else result
def my_csv_reader(filename, /, **kwargs):
with open(filename, 'r', newline='') as file:
for row in csv.reader(file, **kwargs):
yield [_parse_bytes(field) for field in row]
reader = my_csv_reader('bytes_data.csv', delimiter=',')
for row in reader:
print(row)
You can use ast.literal_eval to convert the incorrect fields back to bytes safely:
import ast
def _parse_bytes(bytes_repr):
result = ast.literal_eval(bytes_repr)
if not isinstance(result, bytes):
raise ValueError("Malformed bytes repr")
return result
I am trying to compare the strings of file "formatted_words.txt" with another customised file "dictionary.txt" and in the output I am trying to print those words from "formatted_words.txt"formatted_words file which are present in file "dictionary.txt"dictionary file.
from itertools import izip
with open("formatted_words.txt") as words_file:
with open("dictionary.txt") as dict_file:
all_strings = list(map(str.strip,dict_file))
for word in words_file:
for a_string in all_strings:
if word in a_string:
print a_string
Nevertheless, in the output, all the words of the file "formatted_words.txt" are getting printed, though many words from this file are not in the "dictionary.txt".I cannot use any builtin python dictionary.Any help would be appreciated.
Using sets:
with open('formatted_words.txt') as words_file:
with open('dictionary.txt') as dict_file:
all_strings = set(map(str.strip, dict_file))
words = set(map(str.strip, words_file))
for word in all_strings.intersection(words):
print(word)
Prints nothing because the intersection is empty
I'm trying to print several lines from a text file onto python, where it is outputted. My current code is:
f = open("sample.txt", "r").readlines()[2 ,3]
print(f)
However i'm getting the error message of:
TypeError: list indices must be integers, not tuple
Is there anyway of fixing this or printing multiple lines from a file without printing them out individually?
You are trying to pass a tuple to the [...] subscription operation; 2 ,3 is a tuple of two elements:
>>> 2 ,3
(2, 3)
You have a few options here:
Use slicing to take a sublist from all the lines. [2:4] slices from the 3rd line and includes the 4th line:
f = open("sample.txt", "r").readlines()[2:4]
Store the lines and print specific indices, one by one:
f = open("sample.txt", "r").readlines()
print f[2].rstrip()
print f[3].rstrip()
I used str.rstrip() to remove the newline that's still part of the line before printing.
Use itertools.islice() and use the file object as an iterable; this is the most efficient method as no lines need to be stored in memory for more than just the printing work:
from itertools import islice
with open("sample.txt", "r") as f:
for line in islice(f, 2, 4):
print line.rstrip()
I also used the file object as a context manager to ensure it is closed again properly once the with block is done.
Assign the whole list of lines to a variable, and then print lines 2 and 3 separately.
with open("sample.txt", "r") as fin:
lines = fin.readlines()
print(lines[2])
print(lines[3])
I have a list of more than 10k os string that look like different versions of this (HN5ML6A02FL4UI_3 [14 numbers or letters_1-6]), where some are duplicates except for the _1 to _6.
I am trying to find a way to list these and remove the duplicate 14 character (that comes before the _1-_6).
Example of part of the list:
HN5ML6A02FL4UI_3
HN5ML6A02FL4UI_1
HN5ML6A01BDVDN_6
HN5ML6A01BDVDN_1
HN5ML6A02GVTSV_3
HN5ML6A01CUDA2_1
HN5ML6A01CUDA2_5
HN5ML6A02JPGQ9_5
HN5ML6A02JI8VU_1
HN5ML6A01AJOJU_5
I have tried versions of scripts using Reg Expressions: var n = /\d+/.exec(info)[0]; into the following that were posted into my previous question. and
I also used a modified version of the code from : How can I strip the first 14 characters in an list element using python?
More recently I used this script and I am still not getting the correct output.
import os, re
def trunclist('rhodopsins_play', 'hope4'):
with open('rhodopsins_play','r') as f:
newlist=[]
trunclist=[]
for line in f:
if line.strip().split('_')[0] not in trunclist:
newlist.append(line)
trunclist.append(line.split('_')[0])
print newlist, trunclist
# write newlist to file, with carriage returns
with open('hope4','w') as out:
for line in newlist:
out.write(line)
My inputfile.txt contains more than 10k of data which looks like the list above, where the important part are the characters are in front of the '_' (underscore), then outputting a file of the uniquified ABCD12356_1.
Can someone help?
Thank you for your help
Import python and run this script that is similar to the above. It is slitting at the '_' This worked on the file
def trunclist(inputfile, outputfile):
with open(inputfile,'r') as f:
newlist=[]
trunclist=[]
for line in f:
if line.strip().split('_')[0] not in trunclist:
newlist.append(line)
trunclist.append(line.split('_')[0])
print newlist, trunclist
# write newlist to file, with carriage returns
with open(outputfile,'w') as out:
for line in newlist:
out.write(line)