This question already has answers here:
Is there a built in function for string natural sort?
(23 answers)
Closed 3 years ago.
I have a list of strings that I am trying to organize numerically it looks like this :
List=['Core_0_0.txt', 'Core_0_1.txt','Core_0_2.txt',...'Core_1_0.txt','Core_2_3.txt', ]
but when I sort it sorted(List)
It doesn't sort the list properly.
It's very important that I keep the values as strings and they must be ordered by the number; I.E. 0_1, 0_2,0_3....31_1, they all have Core_X_X.txt How would I do this.
If you can assume all your entries will look like *_N1_N2.txt, you can use the str.split method along with a sorting key function to sort your list properly. It might look something like this
sorted_list = sorted(List, key = lambda s: (int(s.split("_")[1]), int(s.split("_")[2].split(".")[0])))
Essentially, this internally creates tuples like (N1, N2) where your file is named *_N1_N2.txt and sorts based on the N1 value. If there's a tie, it will resort to the N2 value.
Your question is a possible duplicate of another question.
Which I am posting for you here again.
you just need to change 'alist' to your 'List'.
import re
def atoi(text):
return int(text) if text.isdigit() else text
def natural_keys(text):
'''
alist.sort(key=natural_keys) sorts in human order
http://nedbatchelder.com/blog/200712/human_sorting.html
(See Toothy's implementation in the comments)
'''
return [ atoi(c) for c in re.split(r'(\d+)', text) ]
alist=[
"something1",
"something12",
"something17",
"something2",
"something25",
"something29"]
alist.sort(key=natural_keys)
print(alist)
yields
['something1', 'something2', 'something12', 'something17', 'something25', 'something29']
Related
How can I convert a list that has entries like "MAX_PAYLOAD NVARCHAR(5)" to a dictionary that contains key value pairs like "MAX_PAYLOAD" : "NVARCHAR(5)" ?
Assuming that this string is representative of what you're going to see, you might be able to simply split on the space in the middle to create a tuple, then create a dictionary from those tuples.
lines = [
"MAX_PAYLOAD NVARCHAR(5)",
"MIN_PAYLOAD NVARCHAR(4)",
]
broken_lines = [line.split(maxsplit=1) for line in lines]
assert dict(broken_lines) == {'MAX_PAYLOAD': 'NVARCHAR(5)', 'MIN_PAYLOAD': 'NVARCHAR(4)'}
If you might have other whitespaces or something, figure out a different splitting function that'll work for you.
I am an extremely begginer learning python to tackle some biology problems, and I came across lists and its various methods. Basically, when I am running print to my variable I get None as return.
Example, trying to print a sorted list assigned to a variable
list1=[1,3,4,2]
sorted=list1.sort()
print(sorted)
I receive None as return. Shouldn't this provide me with [1,2,3,4]
However, when printing the original list variable (list1), it gives me the sorted list fine.
Because the sort() method will always return None. What you should do is:
list1=[1,3,4,2]
list1.sort()
print(list1)
Or
list1=[1,3,4,2]
list2 = sorted(list1)
print(list2)
You can sort lists in two ways. Using list.sort() and this will sort list, or new_list = sorted(list) and this will return a sorted list new_list and list will not be modified.
So, you can do this:
list1=[1,3,4,2]
sorted=sorted(list1)
print(sorted)
Or you can so this:
list1=[1,3,4,2]
list1.sort()
print(list1)
{
"raw_output": {
"data": {
"sleeps": "[\"{'summaryId': 'x209bf59-59b7574c-594c', 'durationInSeconds': 22860, 'startTimeInSeconds': 1505187660, 'startTimeOffsetInSeconds': -14400, 'deepSleepDurationInSeconds': 7680, 'lightSleepDurationInSeconds': 14100, 'awakeDurationInSeconds': 1080, 'validation': 'AUTO_TENTATIVE'}\", \"{'summaryId': 'x209bf59-59b7574c-6180', 'durationInSeconds': 24960, 'startTimeInSeconds': 1505187660, 'startTimeOffsetInSeconds': -14400, 'deepSleepDurationInSeconds': 7680, 'lightSleepDurationInSeconds': 16140, 'awakeDurationInSeconds': 1140, 'validation': '`AUTO_MANUAL`'}\"]",
},
for example: I would like to access the value of validation of the first dict.
The data embedded in strings needs to be parsed out, ast.literal_eval() can help with that, e.g.:
In []:
import ast
for d in ast.literal_eval(data['raw_output']['data']['sleeps']):
i = ast.literal_eval(d)
print(i['validation'])
Out[]:
AUTO_TENTATIVE
`AUTO_MANUAL`
Your value for sleeps appears to be a string. You need it to be a list. You would may want to replace the string with a list of dictionaries following in order to make it readily index-able. (assuming the dictionary you printed out and posted was stored in a variable called d)
d["raw_output"]["sleeps"] = [eval(k) for k in eval(d["raw_output"]["sleeps"])]
With this done you can now print the value of validation from the first entry as follows.
print(d["raw_output"]["sleeps"][0]['validation'])
As #AChampion pointed out (Epic user name btw) you probably want to
use ast.literal_eval instead of eval.
I hope this helps!
dict["raw_output"]["data"]["sleeps"][0]["validation"] in this way you can access the value of validation.
I'm very new in python (I usually write in php). I want to understand how to store information in an associative array, and if you can explain me whats the difference of "tuples", "arrays", "dictionary" and "list" will be wonderful (I tried to read different source but I still not caching it).
So This is my code:
#!/usr/bin/python3.4
import csv
import string
nidless_keys = dict()
nidless_keys = ['test_string1','test_string2'] #this contain the string to
# be searched in linesreader
data = {'type':[],'id':[]} #here I want to store my information
with open('path/to/csv/file.csv',newline="") as csvfile:
linesreader = csv.reader(csvfile,delimiter=',',quotechar="|")
for row in linesreader: #every line in this csv have a url like
#www.test.com/?test_string1&id=123456
current_row_string = str(row)
for needle in nidless_keys:
current_needle = str(needle)
if current_needle in current_row_string:
data[current_needle[current_row_string[-8:]]) += 1 # also I
#need to count per every id how much rows there are.
In conclusion:
my_data_stored = [current_needle][current_row_string[-8]]
current_row_string[-8] is a url which the last 8 digit of the url is an ID.
So the array should looks like this at the end of the script:
test_string1 = 123456 = 20
= 256468 = 15
test_string2 = 123155 = 10
Edit 1:
Which type I need here to store the information?
Can you tell me how to resolve this script?
It seems you want to count how many times an ID in combination with a test string occurs.
There can be multiple ID/count combinations associated with every test string.
This suggests that you should use a dictionary indexed by the test strings to store the results. In that dictionary I would suggest to store collections.Counter objects.
This way, you would have to add a special case when a key in the results dictionary isn't found to add an empty Counter. This is a common problem, so there is a specialized form of dictionary in the collections module called defaultdict.
import collections
import csv
# Using a tuple for the keys so it cannot be accidentally modified
keys = ('test_string1', 'test_string2')
result = collections.defaultdict(collections.Counter)
with open('path/to/csv/file.csv',newline="") as csvfile:
linesreader = csv.reader(csvfile,delimiter=',',quotechar="|")
for row in linesreader:
for key in keys:
if key in row:
id = row[-6:] # ID's are six digits in your example.
# The first index is into the dict, the second into the Counter.
result[key][id] += 1
There is an even easier way, by using regular expressions.
Since you seem to treat every row in a CSV file as a string, there is little need to use the CSV reader, so I'll just read the whole file as text.
import re
with open('path/to/csv/file.csv') as datafile:
text = datafile.read()
pattern = r'\?(.*)&id=(\d+)'
The pattern is a regular expression. This is a large topic in and of itself, so I'll only cover briefly what it does. (You might also want to check out the relevant HOWTO) At first glance it looks like complete gibberish, but it is actually a complete language.
In looks for two things in a line. Anything between ? and &id=, and a sequence of digits after &id=.
I'll be using IPython to give an example.
(If you don't know it, check out IPython. It is great for trying things and see if they work.)
In [1]: import re
In [2]: pattern = r'\?(.*)&id=(\d+)'
In [3]: text = """www.test.com/?test_string1&id=123456
....: www.test.com/?test_string1&id=123456
....: www.test.com/?test_string1&id=234567
....: www.test.com/?foo&id=234567
....: www.test.com/?foo&id=123456
....: www.test.com/?foo&id=1234
....: www.test.com/?foo&id=1234
....: www.test.com/?foo&id=1234"""
The text variable points to the string which is a mock-up for the contents of your CSV file.
I am assuming that:
every URL is on its own line
ID's are a sequence of digits.
If these assumptions are wrong, this won't work.
Using findall to extract every match of the pattern from the text.
In [4]: re.findall(pattern, test)
Out[4]:
[('test_string1', '123456'),
('test_string1', '123456'),
('test_string1', '234567'),
('foo', '234567'),
('foo', '123456'),
('foo', '1234'),
('foo', '1234'),
('foo', '1234')]
The findall function returns a list of 2-tuples (that is key, ID pairs). Now we just need to count those.
In [5]: import collections
In [6]: result = collections.defaultdict(collections.Counter)
In [7]: intermediate = re.findall(pattern, test)
Now we fill the result dict from the list of matches that is the intermediate result.
In [8]: for key, id in intermediate:
....: result[key][id] += 1
....:
In [9]: print(result)
defaultdict(<class 'collections.Counter'>, {'foo': Counter({'1234': 3, '123456': 1, '234567': 1}), 'test_string1': Counter({'123456': 2, '234567': 1})})
So the complete code would be:
import collections
import re
with open('path/to/csv/file.csv') as datafile:
text = datafile.read()
result = collections.defaultdict(collections.Counter)
pattern = r'\?(.*)&id=(\d+)'
intermediate = re.findall(pattern, test)
for key, id in intermediate:
result[key][id] += 1
This approach has two advantages.
You don't have to know the keys in advance.
ID's are not limited to six digits.
A brief summary of the python data types you mentioned:
A dictionary is an associative array, aka hashtable.
A list is a sequence of values.
An array is essentially the same as a list, but limited to basic datatypes. My impression is that they only exists for performance reasons, don't think I've ever used one. If performance is that critical to you, you probably don't want to use python in the first place.
A tuple is a fixed-length sequence of values (whereas lists and arrays can grow).
Lets take them one by one.
Lists:
List is a very naive kind of data structure similar to arrays in other languages in terms of the way we write them like:
['a','b','c']
This is a list in python , but seems very similar to array structure.
However there is a very large difference in the way lists are used in python and the usual arrays.
Lists are heterogenous in nature. This means that we can store any kind of data simultaneously inside it like:
ls = [1,2,'a','g',True]
As you can see, we have various kinds of data within a list and is a valid list.
However, one important thing about them is that we can access the list items using zero based indices. So we can write:
print ls[0],ls[3]
output: 1 g
Dictionary:
This datastructure is similar to a hash map data structure. It contains a (key,Value) pair. An empty dictionary looks like:
dc = {}
Now, to store a key,value pair, e.g., ('potato',3),(tomato,5), we can do as:
dc['potato'] = 3
dc['tomato'] = 5
and we saved the data in the dictionary dc.
The important thing is that we can even store another data structure element like a list within a dictionary like:
dc['list1'] = ls , where ls is the list defined above.
This shows the power of using dictionary.
In your case, you have difined a dictionary like this:
data = {'type':[],'id':[]}
This means that your dictionary will consist of only two keys and each key corresponds to a list, which are empty for now.
Talking a bit about your script, the expression :
current_row_string[-8:]
doesn't make a sense. The index should have been -6 instead of -8 that would give you the id part of the current row.
This part is the id and should have been stored in a variable say :
id = current_row_string[-6:]
Further action can be performed as seen the answer given by Roland.
I want to write a list of strings to a binary file. Suppose I have a list of strings mylist? Assume the items of the list has a '\t' at the end, except the last one has a '\n' at the end (to help me, recover the data back). Example: ['test\t', 'test1\t', 'test2\t', 'testl\n']
For a numpy ndarray, I found the following script that worked (got it from here numpy to r converter):
binfile = open('myfile.bin','wb')
for i in range(mynpdata.shape[1]):
binfile.write(struct.pack('%id' % mynpdata.shape[0], *mynpdata[:,i]))
binfile.close()
Does binfile.write automatically parses all the data if variable has * in front it (such in the *mynpdata[:,i] example above)? Would this work with a list of integers in the same way (e.g. *myIntList)?
How can I do the same with a list of string?
I tried it on a single string using (which I found somewhere on the net):
oneString = 'test'
oneStringByte = bytes(oneString,'utf-8')
struct.pack('I%ds' % (len(oneString),), len(oneString), oneString)
but I couldn't understand why is the % within 'I%ds' above replaced by (len(oneString),) instead of len(oneString) like the ndarray example AND also why is both len(oneString) and oneString passed?
Can someone help me with writing a list of string (if necessary, assuming it is written to the same binary file where I wrote out the ndarray) ?
There's no need for struct. Simply join the strings and encode them using either a specified or an assumed text encoding in order to turn them into bytes.
''.join(L).encode('utf-8')