如何根据行值将tsv文件拆分为较小的tsv文件

Question

I have a tsv file in.txt which I would like to split into a smaller tsv file called out.txt .

I would like to import only the rows of in.txt which contain a string value My String Value in column 6 into out.txt .

import csv

# r is textmode
# rb is binary mode
# binary mode is faster

with open('in.txt','rb') as tsvIn, open('out.txt', 'w') as tsvOut:
    tsvIn = csv.reader(tsvIn, delimiter='\t')
    tsvOut = csv.writer(tsvOut)

    for row in tsvIn:
        if "My String Value" in row:
            tsvOut.writerows(row)

My output looks like this.

D,r,a,m,a

1,9,6,1,-,0,4,-,1,3
H,y,u,n, ,M,o,k, ,Y,o,o
B,e,o,m,-,s,e,o,n, ,L,e,e
M,u,-,r,y,o,n,g, ,C,h,o,i,",", ,J,i,n, ,K,y,u, ,K,i,m,",", ,J,e,o,n,g,-,s,u,k, ,M,o,o,n,",", ,A,e,-,j,a, ,S,e,o

A, ,p,u,b,l,i,c, ,a,c,c,o,u,n,t,a,n,t,',s, ,s,a,l,a,r,y, ,i,s, ,f,a,r, ,t,o,o, ,s,m,a,l,l, ,f,o,r, ,h,i,m, ,t,o, ,e,v,e,n, ,g,e,t, ,a, ,c,a,v,i,t,y, ,f,i,x,e,d,",", ,l,e,t, ,a,l,o,n,e, ,s,u,p,p,o,r,t, ,h,i,s, ,f,a,m,i,l,y,., ,H,o,w,e,v,e,r,",", ,h,e, ,m,u,s,t, ,s,o,m,e,h,o,w, ,p,r,o,v,i,d,e, ,f,o,r, ,h,i,s, ,s,e,n,i,l,e,",", ,s,h,e,l,l,-,s,h,o,c,k,e,d, ,m,o,t,h,e,r,",", ,h,i,s, ,.,.,.

K,o,r,e,a,n,",", ,E,n,g,l,i,s,h

S,o,u,t,h, ,K,o,r,e,a

It should look like this with tab separated values

Drama     Hyn Mok Yoo     A public accountant's salary is far to small for him...etc

Answer 1

There are a few things wrong with your code. Let's look at this line by line..

import csv

Import module csv . Ok.

with open('in.txt','rb') as tsvIn, open('out.txt', 'w') as tsvOut:

With auto-closed binary file read handle tsvIn from in.txt , and text write handle tsvOut from out.txt , do... (Note: you probably want to use mode wb instead of mode w ; see this post )

    tsvIn = csv.reader(tsvIn, delimiter='\t')

Let tsvIn be the result of the call of function reader in module csv with arguments tsvIn and delimiter='\\t' . Ok.

    tsvOut = csv.writer(tsvOut)

Let tsvOut be the result of the call of function writer in module csv with argument tsvOut . You proably want to add another argument, delimiter='\\t' , too.

    for row in tsvIn:

For each element in tsvIn as row , do...

        if "My String Value" in row:

If string "My String Value" is present in row . You mentioned that you wanted to show only those rows whose sixth element was equal to the string, thus you should use something like this instead...

        if len(row) >= 6 and row[5] == "My String Value":

This means: If the length of row is at least 6 , and the sixth element of row is equal to "My String Value" , do...

            tsvOut.writerows(row)

Call method writerows of object tsvOut with argument row . Remember that in Python, a string is just a sequence of characters, and a character is a single-element string. Thus, a character is a sequence. Then, we have that row is, according to the docs, a list of strings, each representing a column of the row. Thus, a row is a list of strings. Then, we have the writerows method, that expects a list of rows, that is, a list of lists of strings, that is, a list of lists of sequences of characters. It happens that you can interpret each of row 's elements as a row, when it's actually a string, and each element of that string as a string (as characters are strings!). All of this means is that you'll get a messy, character-by-character output. You should try this instead...

            tsvOut.writerow(row)

Method writerow expects a single row as an argument, not a list of rows, thus this will yield the expected result.

Answer 2

try this:

import csv

# r is textmode
# rb is binary mode
# binary mode is faster

with open('in.txt','r') as tsvIn, open('out.txt', 'w') as tsvOut:
    reader = csv.reader(tsvIn, delimiter='\t')
    writer = csv.writer(tsvOutm, delimiter='\t')

    [writer.writerow(row) for row in reader if "My String Value" in row]