Get function results using named pipes (python)

Question

I have one dictionary (inverted_index) that maps integer keys to list values all follows:

key          value
101332      1011772  10841334  21363790
101334      1142902
101347      764543

I'm trying to use named pipes so that the user can input a key and then the result will be the list of values. However, I'm not getting any result.

The following is the code I tried:

import os
import errno

def getDocuments(inp):
    return [inverted_index[x] for x in inp]

FIFO = 'dictpipe'

try:
    os.mkfifo(FIFO)
except OSError as oe:
    if oe.errno != errno.EEXIST:
        raise

print("Opening FIFO...")
with open(FIFO) as fifo:
    print("FIFO opened")
    data = set()
    while True:
        data = fifo.read()
        if len(data) == 0:
            print("Writer closed")
            break
        dd = getDocuments(data)
        print(dd)

The following is the result I'm getting:

Terminal 1:  $ python dictpipes.py 
             Opening FIFO...

Terminal 2:  $ echo 101332 | bc > dictpipe

Terminal 1:  $ python dictpipes.py 
             Opening FIFO... 
             FIFO opened 
             [[], [], [], [], [], [], []] 
             Writer closed

As you can see I'm getting a list of empty lists.. the result should be: [1011772, 10841335, 21363790]

Edit: The code used to create the dictionary..

from collections import defaultdict

inverted_index = defaultdict(list)  #inverted index dictionary
forward_index = defaultdict(list) #forward index dictionary

with open('term_dict.txt') as file:
    for line in file:
        items = line.split()
        term, doc = items[0], items[1:]
        for doc in items[1:]:
            inverted_index[term].append(doc)
            forward_index[doc].append(term)

Answer 1

You are getting input as a string and for x in inp in getDocuments iterates through the characters of the string. It finds no values in the dicationary corresponding to "1", "0", "1", "3", "3", or "2" so returns a list of empty lists. Instead (assuming keys are stored as integers in your dictionary), try:

def getDocuments(inp):
    return inverted_index[int(inp)]

Or, if you want the user to be able to enter more than one key, separated by spaces, you can do this by splitting the input:

def getDocuments(inp)
    return [inverted_index[int(x)] for x in inp.split()]

EDIT

As your dictionary is built from a text file, the keys must be strings. So you just need to strip any whitespace (including the newline character "\\n") from the user's input before doing the look-up.

   return inverted_index[inp.strip()]

Alternatively build your dictionary with integers instead of strings, and use the first getDocuments function above.

with open('term_dict.txt') as file:
    for line in file:
        items = line.split()
        term = int(items[0])
        for doc in items[1:]:
            doc_int = int(doc)
            inverted_index[term].append(doc_int)
            forward_index[doc_int].append(term)