Txt to CSV conversion

nooniensoong97
41 ●2 ●3 ●8

slelievre
17779 ●22 ●162 ●352 http://carva.org/samue...

I would like to convert mathematical constants in txt format to csv format where each digit is its own entry in the csv file.

Here is my code so far, which does not do what I want.

import csv

with open('constants/PiDec.txt','r') as rf:

    with open('constants/PiDec.csv','a') as wf:

        csv_writer = csv.writer(wf)

        s_t_r = 1
        i = 1

        f_contents = rf.read(s_t_r)

        while len(f_contents) > 0:

            csv_writer.writerow(f_contents)
            f_contents = rf.read(s_t_r)
            rf.seek(i)
            i = i+1
            f_contents = rf.read(s_t_r)

Comments

Can you give a simplified small example of what PiDec.txt contains and what you want PiDec.csv to look like?

slelievre ( 4 years ago )

First of all I can't call up the full txt. It is Pi to the millionth digit. So I have to call the individual digit, and place each individual digit in it's own cell.

nooniensoong97 ( 4 years ago )

I would eventually like to create a csv database with a bunch of mathematical constants that are all the way out to the millionth digit.

nooniensoong97 ( 4 years ago )

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answered 4 years ago

Sébastien
3321 ●8 ●44 ●91 http://www.slabbe.org/

updated 4 years ago

I think it is better (and faster) to read the file once and for all and put all the content in one string s. Then, you don't need to seek to the good position which is certainly prone to errors:

with open('constants/PiDec.txt','r') as f:
    s = f.read()

Note that you may also create 10^6 digits of pi with sage without reading it from a file, it takes 1 seconds on my computer and about 20s for 10^7 digits:

sage: %time s = str(pi.n(digits=10^6))
CPU times: user 1.18 s, sys: 22.9 ms, total: 1.2 s
Wall time: 1.2 s
sage: %time s = str(pi.n(digits=10^7))
CPU times: user 19.2 s, sys: 366 ms, total: 19.5 s
Wall time: 19.5 s
sage: len(s)
10000001

If I understand correctly your code and what you try to do with the seek calls, you want to put one digit in each line of the csv file, you don't need any comma in your comma separated file, so you don't really need to use csv library for that. Just a basic str join will do the trick.

result = '\n'.join(a for a in s)
with open('constants/PiDec.csv','w') as f:
    f.write(result)

I don't know if there exists a PEP for that, but I would suggest to keep the content of the with statement to the strict necessary (I/O file operations).

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Comments

Thanks for the input. I thought that the number was going to be too big for memory.

nooniensoong97 ( 4 years ago )

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