Missing Tweets from Twitter API (using Tweepy)? - python-2.7

Question

I have been collecting tweets from the past week to collect the past-7-days tweets related to "lung cancer", yesterday, I figured I needed to start collecting more fields, so I added some fields and started re-collecting the same period of Tweets related to "lung cancer" from last week. The problem is, the first time I've collected ~2000 tweets related to lung cancer on 18th, Sept 2014. But last night, it only gave ~300 tweets, when I looked at the time of the tweets for this new set, it's only collecting tweets from something like ~23:29 to 23:59 on 18th Sept 2014. A large chunk of data is obviously missing. I don't think it's something with my code (below), I have tested various ways including deleting most of the fields to be collected and the time of data is still cut off prematurely.
Is this a known issue with Twitter API (when collecting last 7 days' data)? If so, it will be pretty horrible if someone is trying to do serious research. Or is it somewhere in my code that caused this (note: it runs perfectly fine for other previous/subsequent dates)?
import tweepy
import time
import csv
ckey = ""
csecret = ""
atoken = ""
asecret = ""
OAUTH_KEYS = {'consumer_key':ckey, 'consumer_secret':csecret,
'access_token_key':atoken, 'access_token_secret':asecret}
auth = tweepy.OAuthHandler(OAUTH_KEYS['consumer_key'], OAUTH_KEYS['consumer_secret'])
api = tweepy.API(auth)
# Stream the first "xxx" tweets related to "car", then filter out the ones without geo-enabled
# Reference of search (q) operator: https://dev.twitter.com/rest/public/search
# Common parameters: Changeable only here
startSince = '2014-09-18'
endUntil = '2014-09-20'
suffix = '_18SEP2014.csv'
############################
### Lung cancer starts #####
searchTerms2 = '"lung cancer" OR "lung cancers" OR "lungcancer" OR "lungcancers" OR \
"lung tumor" OR "lungtumor" OR "lung tumors" OR "lungtumors" OR "lung neoplasm"'
# Items from 0 to 500,000 (which *should* cover all tweets)
# Increase by 4,000 for each cycle (because 5000-6000 is over the Twitter rate limit)
# Then wait for 20 min before next request (becaues twitter request wait time is 15min)
counter2 = 0
for tweet in tweepy.Cursor(api.search, q=searchTerms2,
since=startSince, until=endUntil).items(999999999): # changeable here
try:
'''
print "Name:", tweet.author.name.encode('utf8')
print "Screen-name:", tweet.author.screen_name.encode('utf8')
print "Tweet created:", tweet.created_at'''
placeHolder = []
placeHolder.append(tweet.author.name.encode('utf8'))
placeHolder.append(tweet.author.screen_name.encode('utf8'))
placeHolder.append(tweet.created_at)
prefix = 'TweetData_lungCancer'
wholeFileName = prefix + suffix
with open(wholeFileName, "ab") as f: # changeable here
writeFile = csv.writer(f)
writeFile.writerow(placeHolder)
counter2 += 1
if counter2 == 4000:
time.sleep(60*20) # wait for 20 min everytime 4,000 tweets are extracted
counter2 = 0
continue
except tweepy.TweepError:
time.sleep(60*20)
continue
except IOError:
time.sleep(60*2.5)
continue
except StopIteration:
break
Update:
I have since tried running the same python scripts on a different computer (which is faster and more powerful than my home laptop). And the latter resulted in the expected number of tweets, I don't know why it's happening as my home laptop works fine for many programs, but I think we could rest the case and rule out the potential issues related to the scripts or Twitter API.

Answer 1

If you want to collect more data, I would highly recommend the streaming api that Tweepy has to offer. It has a much higher rate limit, in fact I was able to collect 500,000 tweets in just one day.
Also your rate limit checking is not very robust, you don't know for sure that Twitter will allow you to access 4000 tweets. From experience, I found that the more often you hit the rate limit the fewer tweets you are allowed and the longer you have to wait.
I would recommend using:
api = tweepy.API(auth, wait_on_rate_limit=True, wait_on_rate_limit_notify=True)
so that your application will not exceed the rate limit, alternatively you should check what you have used with:
print (api.rate_limit_status())
and then you can just sleep the thread like you have done.
Also your end date is incorrect. The end date should be '2014-09-21', one higher than whatever todays date is.