Those would be: 965, 988. So the final code will look somewhat closer to this: If getting the indices of the keyword is the only thing you need to do, then storing strings in a list is unnecessary (even if this was just an example you thought of!). Find centralized, trusted content and collaborate around the technologies you use most. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. How to select all items for a particular dimension in a list? You can use defaultdict to create dictionary with list as its value type, then append values. It seems unusual, no? Are self-signed SSL certificates still allowed in 2023 for an intranet server running IIS? In these examples, your color list has seven items, so len (colors) returns 7. For example: Here a try with zip, zip() will makes iterator that aggregates elements based on the iterables passed, and returns an iterator of tuples, so map() function is used to make the tuples to list : One-liner using zip built-in and unpacking. OverflowAI: Where Community & AI Come Together, Accessing the second element of a list for every row in pandas dataframe, Behind the scenes with the folks building OverflowAI (Ep. Are arguments that Reason is circular themselves circular and/or self refuting. So my results should be If you're performing a complete iteration over the list already, the last element will still be referenced by the variable name assigned in the loop: This is not semantically the last thing in the list. OverflowAI: Where Community & AI Come Together, Iterate every 2 elements from list at a time, Behind the scenes with the folks building OverflowAI (Ep. If you're doing something more complicated, you may find it more performant to get the last element in slightly different ways. let's consider a Python list of some of the major airlines in the USA. What is the least number of concerts needed to be scheduled in order that each musician may listen, as part of the audience, to every other musician? Not the answer you're looking for? If you do my_list[-1] this returns the last element of the list. Access the first element of a sorted list. I'm making a basic website and using MySQL to get stored password data. How to find the shortest path visiting all nodes in a connected graph as MILP? What does it mean in terms of energy if power is increasing with time? Making statements based on opinion; back them up with references or personal experience. To traverse Python List except for the last element, there are two ways. Not the answer you're looking for? Python 2.7: import itertools def step_indices (length, step): from_indices = xrange (0, length, step) to_indices = itertools.chain (xrange (step, length, step), [None]) for i, j in . Asking for help, clarification, or responding to other answers. Is there any easy option to keep the double values? So first get a dictionary from the list. By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. For example, user input '1.23456' (5 decimal place-OK) but in my dataframe, I have '1.2345678'. 1. New! What is Mathematica's equivalent to Maple's collect with distributed option? Are self-signed SSL certificates still allowed in 2023 for an intranet server running IIS? Code to get a password from the database: db.selectionQuery function (most likely not relevant): data variable is a which contains [{'password': '71cf12724462a57af2effd96223f13e3cc2d11eb0259bada9abf6a5a5a50c85892cbad9b8e00a01f1b1f4c2cebfb665c34691eb320e3a61b6e22081373cbd424'}]. second_to_last = my_list [-2]. Join two objects with perfect edge-flow at any stage of modelling? Find centralized, trusted content and collaborate around the technologies you use most. How can I return the name of the states based on population from the list? What's the difference between your answer and, Thanks! Example Print the last item of the list: thislist = ["apple", "banana", "cherry"] print(thislist [-1]) How to remove an element from a list by index. (with no additional restrictions). Which generations of PowerPC did Windows NT 4 run on? What is the latent heat of melting for a everyday soda lime glass. How do I turn the list [{'password': '71cf12724462a57af2effd96223f13e3cc2d11eb0259bada9abf6a5a5a50c85892cbad9b8e00a01f1b1f4c2cebfb665c34691eb320e3a61b6e22081373cbd424'}] The Journey of an Electromagnetic Wave Exiting a Router. Is it superfluous to place a snubber in parallel with a diode by default? Connect and share knowledge within a single location that is structured and easy to search. Plumbing inspection passed but pressure drops to zero overnight, Using a comma instead of and when you have a subject with two verbs. In this case, technically it matches but logically it does not. In response to "How do I turn the list into a string": It is returning a dictionary inside of a list, so call the first index of the list to return just the dictionary, then use 'password' as the key for the dictionary to return the password. some_list[-1] is the shortest and most Pythonic. Were all of the "good" terminators played by Arnold Schwarzenegger completely separate machines? Would fixed-wing aircraft still exist if helicopters had been invented (and flown) before them? Find centralized, trusted content and collaborate around the technologies you use most. rev2023.7.27.43548. Since lists can have duplicate items, there may be multiple occurrences of the item we are looking for. Am I betraying my professors if I leave a research group because of change of interest? OverflowAI: Where Community & AI Come Together, python get second value of a tuple in a list [duplicate]. Not the answer you're looking for? [6.0,6.1,6.2 6.8] and [0.5,1.0,1.5,2.0 , .4.5], I want to know if we have a cleaner solution than to. If I allow permissions to an application using UAC in Windows, can it hack my personal files or data? If the idea is to use "alist[-1:]" as a conditional instead of "len(alist) > 0", I think it's much more readable to use the later. Were all of the "good" terminators played by Arnold Schwarzenegger completely separate machines? I have something like: elements = [ (1,1,1), (2,3,7), (3,5,10)] I wish to extract only the second elements of each tuple into a list: seconds = [1, 3, 5] I know that it could be done with a for loop but I wanted to know if there's another way since I have thousands of tuples. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Am I betraying my professors if I leave a research group because of change of interest? I want to access the second element of the list for every row and the end result I am expecting is this : . OverflowAI: Where Community & AI Come Together, Find the index of the second occurrence of a string inside a list, Behind the scenes with the folks building OverflowAI (Ep. Which generations of PowerPC did Windows NT 4 run on? What Is Behind The Puzzling Timing of the U.S. House Vacancy Election In Utah? How can I change elements in a matrix to a combination of other elements? Access Items List items are indexed and you can access them by referring to the index number: Example Get your own Python Server Print the second item of the list: thislist = ["apple", "banana", "cherry"] print(thislist [1]) Try it Yourself Note: The first item has index 0. I seek a SF short story where the husband created a time machine which could only go back to one place & time but the wife was delighted, "Pure Copyleft" Software Licenses? By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. What do multiple contact ratings on a relay represent? My sink is not clogged but water does not drain. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. you have a nested list that you can access this way: To have the second element (the element with index 1) of each sublist, I would suggest a list comprehension: If you want the last element (the element with index -1) of each sublist, you just have to change the index: For the list you shown the two lines will give the same list, but when the sublists have more than two elements the two solution will give different results. As can be seen in a[1] there is a negative value in the array. In the first example, you use a negative value for start. Getting a list when you want an element only postpones the inevitable "list index out of range" - and that's what should happen when attempting to get an element from an empty list. WW1 soldier in WW2 : how would he get caught? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. If I allow permissions to an application using UAC in Windows, can it hack my personal files or data? Previous owner used an Excessive number of wall anchors. Is it unusual for a host country to inform a foreign politician about sensitive topics to be avoid in their speech? My preference is to use IF clauses to test for "null" objects instead of objects that halt my code that I preempt with a try clause. How to Add Items to a List in Python Using the append () Method Using dot notation, we can attach the append () method to a list to add an item to the list. you know the loop will finish (not break or exit due to errors), otherwise it will point to the last element referenced by the loop. Please, New! Seems like you are storing a single string in a list and that seems unnecessary. In fact, you can do much more with this syntax. How do I keep a party together when they have conflicting goals? Were all of the "good" terminators played by Arnold Schwarzenegger completely separate machines? Timings for Python 3.6 for extracting the second element from a 2-tuple list. is there a limit of speed cops can go on a high speed pursuit? @zdimension: There is sometimes a reason to not copy (even half of) the input. How common is it for US universities to ask a postdoc to bring their own laptop computer etc.? Not the answer you're looking for? Get first list index containing sub-string? So this is what I try to achieve. What does it mean in terms of energy if power is increasing with time? "Pure Copyleft" Software Licenses? The zip function does not return a list, but a "zip" object now. In the example below, we find the index of the first occurance and then find the index of the first occurance in the sub-list that begins just after the first occurance. "Who you don't know their name" vs "Whose name you don't know". I have tried converting it to an array, string and dict to no avail. How do I make a flat list out of a list of lists? And as such to me are less sequence object like then returned "null"-sequences which do not halt your code. What I meant to say is that this method works with a given data type. How to iterate over rows in a DataFrame in Pandas. Effect of temperature on Forcefield parameters in classical molecular dynamics simulations. Making statements based on opinion; back them up with references or personal experience. How can Phones such as Oppo be vulnerable to Privilege escalation exploits, I seek a SF short story where the husband created a time machine which could only go back to one place & time but the wife was delighted. Now how do I get the actual password out of this list [{'password': '71cf12724462a57af2effd96223f13e3cc2d11eb0259bada9abf6a5a5a50c85892cbad9b8e00a01f1b1f4c2cebfb665c34691eb320e3a61b6e22081373cbd424'}] and into a string? So adding. OverflowAI: Where Community & AI Come Together, Behind the scenes with the folks building OverflowAI (Ep. For What Kinds Of Problems is Quantile Regression Useful? First, I split from decimal point. The Journey of an Electromagnetic Wave Exiting a Router. Is it superfluous to place a snubber in parallel with a diode by default? How and why does electrometer measures the potential differences? This is different from sets and dictionaries, which are unordered. key function in the sort (), Copy to clipboard New! use a list comprehension to iterate over the keys of the dictionary and extract the corresponding values. New! When you omit pythonic way as is possible, then also returning to project after months/years is much easier. You can also do it with map and itemgetter: This still performs a loop internally though and it is slightly slower than the list comprehension: If you need to iterate over a list then using a for is fine. Do the 2.5th and 97.5th percentile of the theoretical sampling distribution of a statistic always contain the true population parameter? prosecutor. In response to "How do I turn the list into a string": It is returning a dictionary inside of a list, so call the first index of the list to return just the dictionary, then use 'password' as the key for the dictionary to return the password. 594), Stack Overflow at WeAreDevelopers World Congress in Berlin, Temporary policy: Generative AI (e.g., ChatGPT) is banned, Preview of Search and Question-Asking Powered by GenAI, Extract part of 2D-List/Matrix/List of lists in Python. Unpacking "If they have a question for the lawyers, they've got to go outside and the grand jurors can ask questions." How to Use the index () Method The index () method gives us a straightforward way to get the index of an item. 146 I'm trying to obtain the n-th elements from a list of tuples. "Sibi quisque nunc nominet eos quibus scit et vinum male credi et sermonem bene". The some_list[-n] syntax gets the nth-to-last element. Where the distinction being made is that returning an empty list object or empty str object is more "last element"-like then an exception object. Method-3: Getting the last element of the list using the pop () function. Another approach is to use the mathematical concept of remainder and apply it to list indexes. But is not a bad answer. Is it the defaults in values == 1 ?. Say, at least 5 initial number from input matches these value and output the result. Get the second to last item in a List in Python # Use an index of -2 to get the second to last item in a list, e.g. This is another different solution that I used sometimes. Sorry, I tried this before and it does not work. python; pandas; dataframe; . How do I split a list into equally-sized chunks? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing, New! So over twice as fast if you have a 2 tuple pair to just convert to a dict and take the values. We can easily find the second smallest value in a list using a loop in Python. 7 Answers Sorted by: 23 You can try list indexing: data = [ [6.0, 0.5], [6.1, 1.0], [6.2, 1.5], [6.3, 2.0], [6.4, 2.5], [6.5, 3.0], [6.6, 3.5], [6.7, 4.0], [6.8, 4.5]] d1 = [item [0] for item in data] print d1 d2 = [item [1] for item in data] print d2 output : Did active frontiersmen really eat 20,000 calories a day? So lets consider that we have a list a = [1,2,3,4], in Python List can be manipulated to give us part of it or a element of it, using the following command one can easily get the last element. Can Henzie blitz cards exiled with Atsushi? what changes in the dict method? What does it mean in terms of energy if power is increasing with time? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. select specific elements of second dimention of a 2D array. Would you publish a deeply personal essay about mental illness during PhD? Help on built-in function zip in module builtin: zip(seq1 [, seq2 []]) -> [(seq1[0], seq2[0] ), ()]. i have following list: parent_child_list with id-tuples: Example: i would like to print those values which are combined with the id 960. Eliminative materialism eliminates itself - a familiar idea? Making statements based on opinion; back them up with references or personal experience. How to help my stubborn colleague learn new ways of coding? Connect and share knowledge within a single location that is structured and easy to search. I don't know why you'd do it, but for completeness, since reversed returns an iterator (which supports the iterator protocol) you can pass its result to next: But I can't think of a good reason to do this, unless you'll need the rest of the reverse iterator later, which would probably look more like this: To prevent IndexError: list index out of range, use this syntax: lst[-1] is the best approach, but with general iterables, consider more_itertools.last: list[-1] will retrieve the last element of the list without changing the list. Can you have ChatGPT 4 "explain" how it generated an answer? find_nminimum(lis,n) gives the nth minimum in the list. How does this compare to other highly-active people in recorded history? What's the best way to get the index of an elemnt inside of a 2d array? Trying to get the first item in a list within a panda dataframe. How do I split a list into equally-sized chunks? Not the answer you're looking for? if your list length is zero, this solution works while. Making statements based on opinion; back them up with references or personal experience. Which generations of PowerPC did Windows NT 4 run on? from former US Fed. How can I identify and sort groups of text lines separated by a blank line? Is the DC-6 Supercharged? lists instead of tuples: Edit: this solution only works on Python 2.x. rev2023.7.27.43548. Another solution with map (with slightly different syntax than other answers). You have a dictionary in a list. Is it normal for relative humidity to increase when the attic fan turns on? By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. Reversing the list and printing the first element. so that advantage doesnt matter. OverflowAI: Where Community & AI Come Together, Behind the scenes with the folks building OverflowAI (Ep. Problem: Given a list. Note: In Python3, zip returns an iterator, so instead use list(zip(*elements)) to return a list of tuples. Thanks for contributing an answer to Stack Overflow! How to iterate two successive elements of the lists of lists in python ? The first item of colors is at index -7. Assuming you are talking about a list. I was wondering if there was a more elegant way of doing this. What is Mathematica's equivalent to Maple's collect with distributed option? It starts by setting lowest to the lower of the first to elements, and secondLowest to the other element. Then it iterates through the list, checking to see if any values are lower than the lowest so far, or the second lowest so far. Were all of the "good" terminators played by Arnold Schwarzenegger completely separate machines? Has these Umbrian words been really found written in Umbrian epichoric alphabet? For sorting a list of tuples by 2nd item or ith item, we need to pass our custom comparator i.e. How do I make a flat list out of a list of lists? You're down vote is understandable and valid. and the new list to be empty if the prior list was empty. 2 Answers Sorted by: 7 You could just do: print (friends [1]) That would give the second element, it will output: Mark If you want to use a loop, try: for i, v in enumerate (friends): if i == 1: print (v) Output: Mark Python indexing starts from 0, so the second element's index would be 1. 594), Stack Overflow at WeAreDevelopers World Congress in Berlin, Temporary policy: Generative AI (e.g., ChatGPT) is banned, Preview of Search and Question-Asking Powered by GenAI. What is Mathematica's equivalent to Maple's collect with distributed option? Single Predicate Check Constraint Gives Constant Scan but Two Predicate Constraint does not. But unfortunately i forgot that dict cannot have double values so instead of getting 965, 988 as the answer i receive only 965.
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