record=['MAT', '90', '62', 'ENG', '92','88']
course='MAT'
suppose i want to get the marks for MAT or ENG what do i do? I just know how to find the index of the course which is new[4:10].index(course). Idk how to get the marks.
Try this:
i = record.index('MAT')
grades = record[i+1:i+3]
In this case i is the index/position of the 'MAT' or whichever course, and grades are the items in a slice comprising the two slots after the course name.
You could also put it in a function:
def get_grades(course):
i = record.index(course)
return record[i+1:i+3]
Then you can just pass in the course name and get back the grades.
>>> get_grades('ENG')
['92', '88']
>>> get_grades('MAT')
['90', '62']
>>>
Edit
If you want to get a string of the two grades together instead of a list with the individual values you can modify the function as follows:
def get_grades(course):
i = record.index(course)
return ' '.join("'{}'".format(g) for g in record[i+1:i+3])
You can use index function ( see this https://stackoverflow.com/a/176921/) and later get next indexes, but I think you should use a dictionary.
Related
I have a list of strings. Each string has the same length/number of characters in the format
xyzw01.ext or xyzv02.ext, etc.
For example
list 1: ['ABCJ01.ext','CDEJ02.ext','ADEJ01.ext','CDEJ01.ext','ABCJ02.ext','CDEJ03.ext']
list 2: ['ABCJ01.ext','ADEJ01.ext','CDEJ01.ext','RPNJ01.ext','PLEJ01.ext']
I would like from these lists to build new lists with only the strings with highest number.
So from list 1 I would like to get
['ADEJ01.ext','ABCJ02.ext','CDEJ03.ext']
while for list 2 I would like to get the same list since all numbers are 01.
Is there a "simple" way of achieving this?
You can use defaultdict and max
from collections import defaultdict
def fun(lst):
res = defaultdict(list)
for x in lst:
res[x[:4]].append(x)
return [max(res[x], key=lambda x: x[4:6]) for x in res]
lst = ['ABCJ01.ext','CDEJ02.ext','ADEJ01.ext','CDEJ01.ext','ABCJ02.ext','CDEJ03.ext']
lst2 = ['ABCJ01.ext','ADEJ01.ext','CDEJ01.ext','RPNJ01.ext','PLEJ01.ext']
print(fun(lst))
print(fun(lst2))
Output:
['ABCJ02.ext', 'CDEJ03.ext', 'ADEJ01.ext']
['ABCJ01.ext', 'ADEJ01.ext', 'CDEJ01.ext', 'RPNJ01.ext', 'PLEJ01.ext']
The easiest way is probably to use an intermediate data structure, like a dict - sort the list items into buckets based on the first part of their names, and then take the maximum number for each bucket. We can just use the built-in max() without a key, since as-given lexicographic sorting works to find the largest. If that's not sufficient, you could use more regex to take the number out of the item and use it as the key instead.
import re
def filter_list(lst):
prefixes = {}
for item in lst:
# use regex to isolate the non-numeric characters at the start of the string
prefix = re.match(r'^([^0-9]*)', item).group(1)
# make a bucket based on each prefix, and put the item in it
prefixes.setdefault(prefix, [])
prefixes[prefix].append(item)
# make a list comprehension taking the maximum item from each bucket
return [max(value) for value in prefixes.values()]
>>> a = ['ABCJ01.ext','CDEJ02.ext','ADEJ01.ext','CDEJ01.ext','ABCJ02.ext','CDEJ03.ext']
>>> b = ['ABCJ01.ext','ADEJ01.ext','CDEJ01.ext','RPNJ01.ext','PLEJ01.ext']
>>> filter_list(a)
['ABCJ02.ext', 'CDEJ03.ext', 'ADEJ01.ext']
>>> filter_list(b)
['ABCJ01.ext', 'ADEJ01.ext', 'CDEJ01.ext', 'RPNJ01.ext', 'PLEJ01.ext']
In python 3.7+, this should preserve the order of list from the first occurrence of each prefix (i.e. CDEJ03.ext will precede ADEJ01.ext in the output because CDEJ02.ext precedes it in the input).
To get the output in the exact same order as the original list, behavior, you'd want to explicitly reassign the key instead of using .setdefault(), perhaps with a pattern like prefixes[prefix] = prefixes[prefix] if prefix in prefixes else [].
I am trying to sort a list that contain in each index an integer and a string. like the one in the example.
I used sort() and split but I get always the wrong ordered that I expect
def takeSecond(elem):
return elem.split("|")[2]
list = ['|val1: 0|0','|val: 0|80','|val1 0|140','|val1: 0|20','|val1: 0|90']
list.sort(key=takeSecond)
print(list)
that returns:
['|val1: 0|90','|val: 0|80','|val1: 0|20','|val1: 0|0','|val1 0|140']
and I expect to get this:
['|val1: 0|140','|val: 0|90','|val1: 0|80','|val1: 20|0','|val1 0|0']
Where is my mistake in here?
Try this:
l = ['|val1: 0|0','|val: 0|80','|val1 0|140','|val1: 0|20','|val1: 0|90']
l.sort(key=lambda x:int(x.rsplit('|')[-1]), reverse=True)
This will sort your list based on what you need. and the expected output is:
In [18]: l
Out[18]: ['|val1 0|140', '|val1: 0|90', '|val: 0|80', '|val1: 0|20', '|val1: 0|0']
In addition note that:
Do not use list as a variable name. list is a built-in name in python, you will override its functionality .
I have a series of dictionaries which each contain the same keys but their values are different i.e Age in dictionary 1 = 2, Age in dictionary 2 = 4 etc etc but they are broadly identical in structure.
what I would like to do is to randomly select one of these dictionaries and then assign specific values with the dictionary to variables. i.e python randomly chooses Dictionary 1 and then I then want to fill the dictAge variable with the age value from Dictionary 1.
import random
dictList = ['myDict', 'otherDict']
mydict = {
'age' : 10,
'other': "dummy data"
}
.
.
.
randomDict = random.choice(dictList)
dictAge = randomDict['age']
print(dictAge)
In the case of the code above what should happen is:
randomDict is assigned a random value from the distList variable (at the top). This sets which dictionary's values will be used going forward.
I next want the dictAge variable to then be assigned the age value from the selected dictionary. In this case (as mydict is was the only dictionary available) it should be assigned the age value of 10.
The error I am getting is:
TypeError: string indices must be integers
I know this is such a common error but my brain can't quite work out what the best solution is.
(Disclaimer: I haven't used python in ages so I know I am doing something really obviously silly but I can't quite work out what to do).
Right now, you are not actually using the definition of your dicts.
This is because dictList is comprised of strings: ['myDict', 'otherDict'].
So, when doing randomDict = random.choice(dictList), randomDict will either be the string 'myDict', or the string 'otherDict'.
Then you are doing randomDict['age'], which means you are trying to slice a string, with a string. As the error suggests, this can't be done and indices can only be ints.
What you want to do, is move the definition of the dictList to be after the definitions of your dicts, and include references to the dicts themselves, not strings. Something like:
mydict = {
'age' : 10,
'other': "dummy data"
}
.
.
.
dictList = [myDict, otherDict]
In the following piece of code:
dictAge = randomDict['age']
You are trying to index the name of dictionary variable (a string) returned by random.choice function.
To make it work you would need to do it using locals:
locals()[randomDict]['age']
or rather correct the dictList to contain the dictionaries instead of their names:
dictList = [myDict, otherDict]
In the latter case please note that myDict and otherDict should be declared before dictList.
In this simple code to read a tsv file of many columes:
InColnames = ['Chr','Pos','Ref','Alt']
tsvin = csv.DictReader(fin, delimiter='\t')
for row in tsvin:
print(', '.join(row[InColnames]))
How can I make the print work ?
The following will do:
for row in tsvin:
print(', '.join(row[col] for col in InCOlNames))
You cannot pass a list of keys to the dict's item-lookup and magically get a list of values. You have to somehow iterate the keys and retrieve each one's value individually. The approach at hand uses a generator expression for that.
I've not ever encountered this type of situation in a Python for loop before.
I have a dictionary of Names (key) and Regions (value). I want to match up each Name with two other names. The matched name cannot be themselves and reversing the elements is not a valid match (1,2) = (2,1). I do not want people from the same Region to be matched together though (unless it becomes impossible).
dict = {
"Tom":"Canada",
"Jerry":"USA",
"Peter":"USA",
"Pan":"Canada",
"Edgar":"France"
}
desired possible output:
[('Tom','Jerry'),('Tom','Peter'),('Jerry','Pan'),('Pan','Peter'),('Edgar','Peter'),('Edgar','Jerry')]
Everyone appears twice, but Jerry and Peter appears more in order for Edgar to have 2 matches with Names from a different region (Jerry and Peter should be chosen randomly here)
Count: Tom: 2, Jerry: 3, Peter: 3, Pan: 2, Edgar: 2
My approach is to convert the names into a list, shuffle them, then create tuple pairs using zip in a custom function. After the function is complete. I use a a for to check for pairings from the same region, if a same pairing region exists, then re-run the custom function. For some reason, when I print the results, I still see pairings between the same regions. What am I missing here?
import random
names=list(dict.keys())
def pairing(x):
random.shuffle(x)
#each person is tupled twice, once with the neighbor on each side
pairs = list(zip(x, x[1:]+x[:1]))
return pairs
pairs=pairing(names) #assigns variable from function to 'pairs'
for matchup in pairs:
if dict[matchup[0]]==dict[matchup[1]]:
break
pairing(names)
pairs=pairing(names)
for matchup in pairs:
print(matchup[0] ,dict[matchup[0]] , matchup[1] , dict[matchup[1]])
Just looking at it, something is clearly broken in the for loop, please help!
I've tried while rather than if in the for loop, but it did not work.
from itertools import combinations
import pandas as pd
import random
dict={'your dictionary'}
#create function to pair names together
def pairing(x):
random.shuffle(x)
#each person is tupled twice, once with the neighbor on each side
pairs = list(zip(x, x[1:]+x[:1]))
for matchup in pairs:
if dict[matchup[0]]==dict[matchup[1]]: #if someone's gym matches their opponent's gym in dictionary, re-run this function
return pairing(x)
return pairs
pairs=pairing(names)
for matchup in pairs:
print(matchup[0] ,dict[matchup[0]] , matchup[1] , dict[matchup[1]])
The trick is to return pairing(x) inside the custom function. This will return new pairings if any elements in the tuple share the same value in the dictionary. If inside the if statement, you go pairing(x) then return pair, it'll return the original tuple list which contains duplicates.