How to query arXiv for a specific year?

I'm using the code shown below in order to retrieve papers from arXiv. I want to retrieve papers that have words "machine" and "learning" in the title. The number of papers is large, therefore I want to implement a slicing by year (published).

How can I request records of 2020 and 2019 in search_query? Please notice that I'm not interested in post-filtering.

import urllib.request

import time
import feedparser

# Base api query url
base_url = 'http://export.arxiv.org/api/query?';

# Search parameters
search_query = urllib.parse.quote("ti:machine learning")
start = 0
total_results = 5000
results_per_iteration = 1000
wait_time = 3

papers = []

print('Searching arXiv for %s' % search_query)

for i in range(start,total_results,results_per_iteration):
    
    print("Results %i - %i" % (i,i+results_per_iteration))
    
    query = 'search_query=%s&start=%i&max_results=%i' % (search_query,
                                                         i,
                                                         results_per_iteration)

    # perform a GET request using the base_url and query
    response = urllib.request.urlopen(base_url+query).read()

    # parse the response using feedparser
    feed = feedparser.parse(response)

    # Run through each entry, and print out information
    for entry in feed.entries:
        #print('arxiv-id: %s' % entry.id.split('/abs/')[-1])
        #print('Title:  %s' % entry.title)
        #feedparser v4.1 only grabs the first author
        #print('First Author:  %s' % entry.author)
        paper = {}
        paper["date"] = entry.published
        paper["title"] = entry.title
        paper["first_author"] = entry.author
        paper["summary"] = entry.summary
        papers.append(paper)
    
    # Sleep a bit before calling the API again
    print('Bulk: %i' % 1)
    time.sleep(wait_time)

According to the arXiv documentation, there is no published or date field available.

What you can do is to sort the results by date (by adding &sortBy=submittedDate&sortOrder=descending to your query parameters) and stop making requests when you reach 2018.

Basically your code should be modified like this:

import urllib.request

import time
import feedparser

# Base api query url
base_url = 'http://export.arxiv.org/api/query?';

# Search parameters
search_query = urllib.parse.quote("ti:machine learning")
i = 0
results_per_iteration = 1000
wait_time = 3
papers = []
year = ""  
print('Searching arXiv for %s' % search_query)

while (year != "2018"): #stop requesting when papers date reach 2018
    print("Results %i - %i" % (i,i+results_per_iteration))
    
    query = 'search_query=%s&start=%i&max_results=%i&sortBy=submittedDate&sortOrder=descending' % (search_query,
                                                         i,
                                                         results_per_iteration)

    # perform a GET request using the base_url and query
    response = urllib.request.urlopen(base_url+query).read()

    # parse the response using feedparser
    feed = feedparser.parse(response)
    # Run through each entry, and print out information
    for entry in feed.entries:
        #print('arxiv-id: %s' % entry.id.split('/abs/')[-1])
        #print('Title:  %s' % entry.title)
        #feedparser v4.1 only grabs the first author
        #print('First Author:  %s' % entry.author)
        paper = {}
        paper["date"] = entry.published
        year = paper["date"][0:4]
        paper["title"] = entry.title
        paper["first_author"] = entry.author
        paper["summary"] = entry.summary
        papers.append(paper)
    # Sleep a bit before calling the API again
    print('Bulk: %i' % 1)
    i += results_per_iteration
    time.sleep(wait_time)

for the "post-filtering" approach, once enough results are collected, I'd do something like this:

papers2019 = [item for item in papers if item["date"][0:4] == "2019"]