If I run the following code:
from nltk.tokenize import word_tokenize
text = "God is Great! I won a lottery."
print(word_tokenize(text))
I get this output:
['God', 'is', 'Great', '!', 'I', 'won', 'a', 'lottery', '.']
In this case, the tokens in the list are appearing in the same order as they are in the input sentence.
However, are they always in the same order as in the input sentence ?
Yes, they are always in the same order as in the input sentence.
The method word_tokenize calls re.findall. Regular expression documentation about re.findall states the following.
Return all non-overlapping matches of pattern in string, as a list of strings. The string is scanned left-to-right, and matches are returned in the order found.
References:
https://www.nltk.org/_modules/nltk/tokenize/punkt.html#PunktLanguageVars.word_tokenize (search word_tokenize on this page)
https://docs.python.org/3/library/re.html (search findall on this page)
https://docs.python.org/2/library/re.html (search findall on this page)
Related
I'm new to Python3 and I am working with large JSON objects. I have a large JSON object which has extra chars coming in between two JSON objects, in between the braces.
For example:
{"id":"121324343", "name":"foobar"}3$£_$£rvcfddkgga£($(>..bu&^783 { "id":"343554353", "name":"ABCXYZ"}'
These extra chars could be anything alphanumeric, special chars or ASCII. They appear in this large JSON multiple times and can be of any length. I'm trying to use regex to identify that pattern to remove them, but regex doesn't seem to work. Here is the regex I used:
(^}\n[a-zA-Z0-9]+{$)
Is there a way of identifying such patter using regex in python?
You can select the dictionary data based on named capture groups. As a bonus, this will also ignore any { or } within the extra chars.
The following pattern works on the provided data:
"\"id\"\:\"(?P<id>\d+?)\"[,\s]+\"name\"\:\"(?P<name>[ \w]+)\""
Example
import re
from pprint import pprint
string = \
"""
{"id":"121324343", "name":"foobar"}3$£_$£rvcfdd{}kgga£($(>..bu&^783 { "id":"343554353", "name":"ABC XYZ"}'
"""
pattern = re.compile(pattern="\"id\"\:\"(?P<id>\d+?)\"[,\s]+\"name\"\:\"(?P<name>[ \w]+)\"")
pprint([match.groupdict() for match in pattern.finditer(string=string)])
Output
[{'id': '121324343', 'name': 'foobar'}, {'id': '343554353', 'name': 'ABC XYZ'}]
Test it out yourself: https://regex101.com/r/82BqbE/1
Notes
For this example I assume the following:
id only contains integer digits.
name is a string that can contain the following characters [a-zA-Z0-9_ ]. (this includes white spaces and underscores).
Assuming the whole json is a single line, and there are no }{ inside the fields themselves, this should be enough
In [1]: import re
In [2]: x = """{"id":"121324343", "name":"foobar"}3$£_$£rvcfddkgga£($(>..bu&^783 { "id":"343554353", "name":"ABCXYZ"}"""
In [3]: print(re.sub(r'(?<=})[^}{]+(?={)', "\n", x))
{"id":"121324343", "name":"foobar"}
{ "id":"343554353", "name":"ABCXYZ"}
You can check the regex here https://regex101.com/r/leIoqE/1
My JSON file looks something like:
{
"generator": {
"name": "Xfer Records Serum",
....
},
"generator": {
"name: "Lennar Digital Sylenth1",
....
}
}
I ask the user for search term and the input is searched for in the name key only. All matching results are returned. It means if I input 's' only then also both the above ones would be returned. Also please explain me how to return all the object names which are generators. The more simple method the better it will be for me. I use json library. However if another library is required not a problem.
Before switching to JSON I tried XML but it did not work.
If your goal is just to search all name properties, this will do the trick:
import re
def search_names(term, lines):
name_search = re.compile('\s*"name"\s*:\s*"(.*' + term + '.*)",?$', re.I)
return [x.group(1) for x in [name_search.search(y) for y in lines] if x]
with open('path/to/your.json') as f:
lines = f.readlines()
print(search_names('s', lines))
which would return both names you listed in your example.
The way the search_names() function works is it builds a regular expression that will match any line starting with "name": " (with varying amount of whitespace) followed by your search term with any other characters around it then terminated with " followed by an optional , and the end of string. Then applies that to each line from the file. Finally it filters out any non-matching lines and returns the value of the name property (the capture group contents) for each match.
My goal is to (1) import Twitter JSON, (2) extract data of interest, (3) create pandas data frame for the variables of interest. Here is my code:
import json
import pandas as pd
tweets = []
for line in open('00.json'):
try:
tweet = json.loads(line)
tweets.append(tweet)
except:
continue
# Tweets often have missing data, therefore use -if- when extracting "keys"
tweet = tweets[0]
ids = [tweet['id_str'] for tweet in tweets if 'id_str' in tweet]
text = [tweet['text'] for tweet in tweets if 'text' in tweet]
lang = [tweet['lang'] for tweet in tweets if 'lang' in tweet]
geo = [tweet['geo'] for tweet in tweets if 'geo' in tweet]
place = [tweet['place'] for tweet in tweets if 'place' in tweet]
# Create a data frame (using pd.Index may be "incorrect", but I am a noob)
df=pd.DataFrame({'Ids':pd.Index(ids),
'Text':pd.Index(text),
'Lang':pd.Index(lang),
'Geo':pd.Index(geo),
'Place':pd.Index(place)})
# Create a data frame satisfying conditions:
df2 = df[(df['Lang']==('en')) & (df['Geo'].dropna())]
So far, everything seems to be working fine.
Now, the extracted values for Geo result in the following example:
df2.loc[1921,'Geo']
{'coordinates': [39.11890951, -84.48903638], 'type': 'Point'}
To get rid of everything except the coordinates inside the squared brackets I tried using:
df2.Geo.str.replace("[({':]", "") ### results in NaN
# and also this:
df2['Geo'] = df2['Geo'].map(lambda x: x.lstrip('{'coordinates': [').rstrip('], 'type': 'Point'')) ### results in syntax error
Please advise on the correct way to obtain coordinates values only.
The following line from your question indicates that this is an issue with understanding the underlying data type of the returned object.
df2.loc[1921,'Geo']
{'coordinates': [39.11890951, -84.48903638], 'type': 'Point'}
You are returning a Python dictionary here -- not a string! If you want to return just the values of the coordinates, you should just use the 'coordinates' key to return those values, e.g.
df2.loc[1921,'Geo']['coordinates']
[39.11890951, -84.48903638]
The returned object in this case will be a Python list object containing the two coordinate values. If you want just one of the values, you can slice the list, e.g.
df2.loc[1921,'Geo']['coordinates'][0]
39.11890951
This workflow is much easier to deal with than casting the dictionary to a string, parsing the string, and recapturing the coordinate values as you are trying to do.
So let's say you want to create a new column called "geo_coord0" which contains all of the coordinates in the first position (as shown above). You could use a something like the following:
df2["geo_coord0"] = [x['coordinates'][0] for x in df2['Geo']]
This uses a Python list comprehension to iterate over all entries in the df2['Geo'] column and for each entry it uses the same syntax we used above to return the first coordinate value. It then assigns these values to a new column in df2.
See the Python documentation on data structures for more details on the data structures discussed above.
BACKGROUND:
I am having issues trying to search through some CSV files.
I've gone through the python documentation: http://docs.python.org/2/library/csv.html
about the csv.DictReader(csvfile, fieldnames=None, restkey=None, restval=None, dialect='excel', *args, **kwds) object of the csv module.
My understanding is that the csv.DictReader assumes the first line/row of the file are the fieldnames, however, my csv dictionary file simply starts with "key","value" and goes on for atleast 500,000 lines.
My program will ask the user for the title (thus the key) they are looking for, and present the value (which is the 2nd column) to the screen using the print function. My problem is how to use the csv.dictreader to search for a specific key, and print its value.
Sample Data:
Below is an example of the csv file and its contents...
"Mamer","285713:13"
"Champhol","461034:2"
"Station Palais","972811:0"
So if i want to find "Station Palais" (input), my output will be 972811:0. I am able to manipulate the string and create the overall program, I just need help with the csv.dictreader.I appreciate any assistance.
EDITED PART:
import csv
def main():
with open('anchor_summary2.csv', 'rb') as file_data:
list_of_stuff = []
reader = csv.DictReader(file_data, ("title", "value"))
for i in reader:
list_of_stuff.append(i)
print list_of_stuff
main()
The documentation you linked to provides half the answer:
class csv.DictReader(csvfile, fieldnames=None, restkey=None, restval=None, dialect='excel', *args, **kwds)
[...] maps the information read into a dict whose keys are given by the optional fieldnames parameter. If the fieldnames parameter is omitted, the values in the first row of the csvfile will be used as the fieldnames.
It would seem that if the fieldnames parameter is passed, the given file will not have its first record interpreted as headers (the parameter will be used instead).
# file_data is the text of the file, not the filename
reader = csv.DictReader(file_data, ("title", "value"))
for i in reader:
list_of_stuff.append(i)
which will (apparently; I've been having trouble with it) produce the following data structure:
[{"title": "Mamer", "value": "285713:13"},
{"title": "Champhol", "value": "461034:2"},
{"title": "Station Palais", "value": "972811:0"}]
which may need to be further massaged into a title-to-value mapping by something like this:
data = {}
for i in list_of_stuff:
data[i["title"]] = i["value"]
Now just use the keys and values of data to complete your task.
And here it is as a dictionary comprehension:
data = {row["title"]: row["value"] for row in csv.DictReader(file_data, ("title", "value"))}
The currently accepted answer is fine, but there's a slightly more direct way of getting at the data. The dict() constructor in Python can take any iterable.
In addition, your code might have issues on Python 3, because Python 3's csv module expects the file to be opened in text mode, not binary mode. You can make your code compatible with 2 and 3 by using io.open instead of open.
import csv
import io
with io.open('anchor_summary2.csv', 'r', newline='', encoding='utf-8') as f:
data = dict(csv.reader(f))
print(data['Champhol'])
As a warning, if your csv file has two rows with the same value in the first column, the later value will overwrite the earlier value. (This is also true of the other posted solution.)
If your program really is only supposed to print the result, there's really no reason to build a keyed dictionary.
import csv
import io
# Python 2/3 compat
try:
input = raw_input
except NameError:
pass
def main():
# Case-insensitive & leading/trailing whitespace insensitive
user_city = input('Enter a city: ').strip().lower()
with io.open('anchor_summary2.csv', 'r', newline='', encoding='utf-8') as f:
for city, value in csv.reader(f):
if user_city == city.lower():
print(value)
break
else:
print("City not found.")
if __name __ == '__main__':
main()
The advantage of this technique is that the csv isn't loaded into memory and the data is only iterated over once. I also added a little code the calls lower on both the keys to make the match case-insensitive. Another advantage is if the city the user requests is near the top of the file, it returns almost immediately and stops looking through the file.
With all that said, if searching performance is your primary consideration, you should consider storing the data in a database.
I am just learning nltk using Python. I am using POS tagging. What I want to know is how do I use the tags. For example, this is the pseudocode:
words = []
teststr = "George did well in the test."
tokens = nltk.word_tokenize(teststr)
words = nltk.pos_tag(tokens)
I want to do something like this:
if words[i] == "proper noun":
#do something
How do I check whether a word is a noun or a verb or any other part of speech.
Can someone please help me out here?
Thanks.
If you look at the results of your pos_tag function call you are returned the following list:
[('George', 'NNP'), ('did', 'VBD'), ('well', 'RB'), ('in', 'IN'), ('the', 'DT'), ('test', 'NN'), ('.', '.')]
If you iterate through the list to do something based on the value being a proper noun you would need the following code:
if words[i][1] == 'NNP':
# do something
NNP is a singular proper noun. Each entry in that list is a tuple which the first value being the word and the second value being the pos.