读取一个文件中的行并找到所有以另一个txt文件中列出的4个字母开头的字符串

Question

I have 2 txt files (a and b_).

file_a.txt contains a long list of 4-letter combinations (one combination per line):

aaaa
bcsg
aacd
gdee
aadw
hwer
etc.

file_b.txt contains a list of letter combinations of various length (some with spaces):

aaaibjkes
aaleoslk
abaaaalkjel
bcsgiweyoieotpwe
csseiolskj
gaelsi asdas
aaaloiersaaageehikjaaa
hwesdaaadf wiibhuehu
bcspwiopiejowih
gdeaes
aaailoiuwegoiglkjaaake
etc.

I am looking for a python script that would allow me to do the following:

1. read file_a.txt line by line
2. take each 4-letter combination (eg aaai)
3. read file_b.txt and find all the various-length letter combinations starting with the 4-letter combination (eg. aaai bjkes, aaai loiersaaageehikjaaa, aaai loiuwegoiglkjaaaike etc.)
4. print the results of each search in a separate txt file named with the 4-letter combination.

File aaai.txt:

aaaibjkes 
aaailoiersaaageehikjaaa
aaailoiuwegoiglkjaaake
etc.

File bcsi.txt:

bcspwiopiejowih
bcsiweyoieotpwe
etc.

I'm sorry I'm a newbie. Can someone point me in the right direction, please. So far I've got only:

#I presume I will have to use regex at some point
import re

file1 = open('file_a.txt', 'r').readlines()
file2 = open('file_b.txt', 'r').readlines()

#Should I look into findall()?

Answer 1

I hope this would help you;

file1 = open('file_a.txt', 'r')
file2 = open('file_b.txt', 'r')

#get every item in your second file into a list 
mylist = file2.readlines()

# read each line in the first file
while file1.readline():
    searchStr = file1.readline()
    # find this line in your second file
    exists = [s for s in mylist if searchStr in s]
    if (exists):
        # if this line exists in your second file then create a file for it
        fileNew = open(searchStr,'w')
        for line in exists:
            fileNew.write(line)

        fileNew.close()

    file1.close()

Answer 2

What you can do is to open both files and run both files down line by line using for loops.

You can have two for loops, the first one reading file_a.txt as you will be reading through it only once. The second will read through file_b.txt and look for the string at the start.

To do so, you will have to use .find() to search for the string. Since it is at the start, the value should be 0 .

file_a = open("file_a.txt", "r")
file_b = open("file_b.txt", "r")

for a_line in file_a:
    # This result value will be written into your new file
    result = ""
    # This is what we will search with
    search_val = a_line.strip("\n")
    print "---- Using " + search_val + " from file_a to search. ----"
    for b_line in file_b:
        print "Searching file_b using " + b_line.strip("\n")
        if b_line.strip("\n").find(search_val) == 0:
            result += (b_line)
    print "---- Search ended ----"
    # Set the read pointer to the start of the file again
    file_b.seek(0, 0)

    if result:
        # Write the contents of "results" into a file with the name of "search_val"
        with open(search_val + ".txt", "a") as f:
            f.write(result)

file_a.close()
file_b.close()

Test Cases:

I am using the test cases in your question:

file_a.txt

aaaa
bcsg
aacd
gdee
aadw
hwer

file_b.txt

aaaibjkes
aaleoslk
abaaaalkjel
bcsgiweyoieotpwe
csseiolskj
gaelsi asdas
aaaloiersaaageehikjaaa
hwesdaaadf wiibhuehu
bcspwiopiejowih
gdeaes
aaailoiuwegoiglkjaaake

The program produces an output file bcsg.txt as it is supposed to with bcsgiweyoieotpwe inside.

Answer 3

Try this:

f1 = open("a.txt","r").readlines()
f2 = open("b.txt","r").readlines()
file1 = [word.replace("\n","") for word in f1]
file2 = [word.replace("\n","") for word in f2]

data = []
data_dict ={}
for short_word in file1:
    data += ([[short_word,w] for w in file2 if w.startswith(short_word)])

for single_data in data:
    if single_data[0] in data_dict:
        data_dict[single_data[0]].append(single_data[1])
    else:
        data_dict[single_data[0]]=[single_data[1]]

for key,val in data_dict.iteritems():
    open(key+".txt","w").writelines("\n".join(val))
    print(key + ".txt created")