How to increase the python speed over loops?

问题

I have a dataset of 370k records stored in a Pandas Dataframe which needs to be integrated. I tried multiprocessing, threading, Cpython and loop unrolling. But I was not successful and the time shown to compute was 22 hrs. The task is as follows:

%matplotlib inline  
from numba import jit, autojit
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt

with open('data/full_text.txt', encoding = "ISO-8859-1") as f:
 strdata=f.readlines()
data=[]

for string in strdata:
 data.append(string.split('\t'))

df=pd.DataFrame(data,columns=["uname","date","UT","lat","long","msg"])

df=df.drop('UT',axis=1)

df[['lat','long']] = df[['lat','long']].apply(pd.to_numeric)

from textblob import TextBlob
from tqdm import tqdm

df['polarity']=np.zeros(len(df))

Threading:

 from queue import Queue
 from threading import Thread
 import logging
 logging.basicConfig(
 level=logging.DEBUG,
  format='(%(threadName)-10s) %(message)s',
  )


class DownloadWorker(Thread):
   def __init__(self, queue):
       Thread.__init__(self)
       self.queue = queue

   def run(self):
       while True:
           # Get the work from the queue and expand the tuple
         lowIndex, highIndex = self.queue.get()
         a = range(lowIndex,highIndex-1)
         for i in a:
            df['polarity'][i]=TextBlob(df['msg'][i]).sentiment.polarity
         self.queue.task_done()

  def main():
   # Create a queue to communicate with the worker threads
   queue = Queue()
   # Create 8 worker threads
   for x in range(8):
     worker = DownloadWorker(queue)
     worker.daemon = True
     worker.start()
  # Put the tasks into the queue as a tuple
   for i in tqdm(range(0,len(df)-1,62936)):
     logging.debug('Queueing')
     queue.put((i,i+62936 ))
     queue.join()
     print('Took {}'.format(time() - ts))

 main()

Multiprocessing with loop unrolling:

pool = multiprocessing.Pool(processes=2)
r = pool.map(assign_polarity, df)
pool.close()

def assign_polarity(df):
   a=range(0,len(df),5)
   for i in tqdm(a):
       df['polarity'][i]=TextBlob(df['msg'][i]).sentiment.polarity
       df['polarity'][i+1]=TextBlob(df['msg'][i+1]).sentiment.polarity
       df['polarity'][i+2]=TextBlob(df['msg'][i+2]).sentiment.polarity
       df['polarity'][i+3]=TextBlob(df['msg'][i+3]).sentiment.polarity
       df['polarity'][i+4]=TextBlob(df['msg'][i+4]).sentiment.polarity

How to increase the speed of computation? or storing the computation in dataframe in a faster way? My laptop configuration

Ram: 8GB
Physical cores: 2
Logical cores: 8
Windows 10

Implementing Multiprocessing gave me a higher computation time. Threading was being executed sequentially (I think because of GIL) Loop Unrolling gave me the same computation speed. Cpython was giving me errors while importing libraries.

回答1:

ASD -- I noticed that storing something in a df iteratively is VERY slow. I'd try to store your TextBlobs in a list (or another structure) and then converting that list into a column of a df.

来源：https://stackoverflow.com/questions/43847238/how-to-increase-the-python-speed-over-loops

标签

python

pandas

parallel-processing

iteration

computation