I am a newbie to python and just learning things as I do my project and here I have a list of lists which I need to compare between the second and last column and get the output for the one which has the largest distance. Moreover, I am replicating a list. If someone could help me to do it within a single list of lists in ag it could be really helpful.
Thanks in advance
if this is an INPUT then the output should be,
ag = [['chr12','XX',1,5,4],['chr12','XX',2,5,3],['chr13','ZZ',6,10,4],['chr13','ZZ',8,9,1],['ch14','YY',12,15,3],['ch14','YY',12,15,3]]EXPECTED OUTPUT:['chr12','XX',1,5,4]['chr13','ZZ',6,10,4]['ch14','YY',12,15,3]#However I tried of replicating the list like
#INPUT
ag = [['chr12','XX',1,5,4],['chr12','XX',2,5,3],['chr13','ZZ',6,10,4],['chr13','ZZ',8,9,1],['ch14','YY',12,15,3],['ch14','YY',12,15,3]]bg = [['chr12','XX',1,5,4],['chr12','XX',2,5,3],['chr13','ZZ',6,10,4],['chr13','ZZ',8,9,1],['ch14','YY',12,15,3],['ch14','YY',12,15,3]]#The code which I tried wasc= []
for i in ag:for j in bg:if i[0]==j[0] and i[1]==j[1] and i[4]>j[4]:c.append(i)the output which i get is
[['chr12', 'XX', 1, 5, 4], ['chr13', 'ZZ', 6, 10, 4]]
In short: To compare items in an iterable (e.g. list) of lists, use the keyword agument key of the max/min function. It takes a function or lambda expression and compares the given values by the result of the key function when given each value.
Assuming that what you really want is to reduce a list of lists so that the entries' second elements are unique and that you want the last elements to determin which entry to keep in case of redundant 2nd values:
If there is any problem regarding iteration, itertools has the answer. In this case, we just need the groupby method and standard Python's max method with the keyword argument key.
from itertools import groupbydef filter(matrix):filtered = [] # create a result list to hold the rows (lists) we wantfor key, rows in groupby(matrix, lambda row: row[1]): # get the rows grouped by their 2nd element and iterate over thatfiltered.append(max(rows, key=lambda row: row[-1])) # add the line that among its group has the largest last value to our resultreturn filtered # return the result
We could squeeze this into a single generator expression or list comprehension but for a beginner, the above code should be complex enought.
Please be sure to follow Stack Overflow's guidelines for future questions to prevent low ratings and ensure prompt and high quality answers.