Python combine two lists different length

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Merge two Dataframes on index of one dataframe and some column of other dataframe. What if we want to merge two dataframe by index of first dataframe and on some column of second dataframe ? For example let’s change the dataframe salaryDfObj by adding a new column ‘EmpID‘ and also reset it’s index i.e. Mar 20, 2019 · Python Difference Between Two Lists. Lists in Python can be performed in different ways, but it depends on the outcome required. Two popular methods of comparison are set() and cmp(). The set() function creates an object that is a set object. The cmp() function is used to compare two elements or lists and return a value based on the arguments ... Sep 30, 2019 · Output: As shown in the output, the NaN values in the series were replaced by 5 before combining the series. 0 5.0 1 3.0 2 2.0 3 5.0 4 6.0 5 3.0 6 9.0 7 21.0 8 11.0 9 5.0 10 4.0 11 8.0 dtype: float64 Jan 23, 2009 · The merge() as well as the rbind() function do not help here as they require equal lengths. I posted this matter on r-help as my first solution was somewhat awkward and could not be generalized to any data frames or list of data frames. The first solution was posted by Charles C. Berry. myList is a list containing the data frames as elements Mar 17, 2019 · Pandas : How to Merge Dataframes using Dataframe.merge() in Python – Part 1 Merging Dataframe on a given column with suffix for similar column names If there are some similar column names in both the dataframes which are not in join key then by default x & y is added as suffix to them. For example: merge_lists ( [ [1,2], [1]] , [3,4]) = [ [1,2,3], [1,4]] The answers currently provided generate lists of higher dimensions in cases like this. python python-2.7 list merge list-comprehension. share. May 18, 2018 · In this short tutorial, you will learn how to combine two lists together in Python using extend (in place) and concatenation (out of place). Want to learn mo... Dec 30, 2018 · Given lists of same length, write a Python program to store alternative elements of given lists in a new list. Let’s discuss certain ways in which this can be performed. Method #1 : Using map () + list comprehension. map () is used to handle the interleave of lists and the task of insertion at alternate is performed by the list comprehension part of the shorthand code. Write a function that takes two lists, each of which is sorted in increasing order, and merges the two together into one list which is in increasing order and return it. For example, consider lists {1, 3, 5} and {2, 4, 6, 7} . The algorithm to merge two lists and sort it : Create two empty lists. We will populate these lists by taking the inputs from the user. To create an empty list, you can use an empty square bracket. First, take the total number for the first list from the user. The total item count for both lists can be different. We are going to merge both lists, so the list size doesn’t matter. Merge two Dataframes on index of one dataframe and some column of other dataframe. What if we want to merge two dataframe by index of first dataframe and on some column of second dataframe ? For example let’s change the dataframe salaryDfObj by adding a new column ‘EmpID‘ and also reset it’s index i.e. map accepts *args and "zips" them implicitly:. sums_list = sum(map(lambda *x:list(x), list1, list2), []) Although I guess that's actually clunkier :(Using sum to accumulate a list is slow, btw (sum is explicitly designed to reject strings because they have the same algorithmic problem. map accepts *args and "zips" them implicitly:. sums_list = sum(map(lambda *x:list(x), list1, list2), []) Although I guess that's actually clunkier :(Using sum to accumulate a list is slow, btw (sum is explicitly designed to reject strings because they have the same algorithmic problem. this function creates a dictionary from given two lists, it prepares a dict by considering the length of the lists. it prepares the dict only to the items present in the 1st list 'a'. If length of list 'b' is less than the length of list 'a', then it appends 'None' to 'b' to make its length equal to the length of list 'a'. Python: merge two lists by putting their elements at alternate positions +2 votes . asked Apr 16, 2019 in Programming Languages by pythonuser (14.3k points) There are various methods to find and store the common elements from two lists. How to find the common elements in two lists in Python. To learn the various ways to find the common elements from two lists in Python. We have to make two separate lists. We will learn all the ways with an example. Using a function. Example 1: Make a function for ... Can either be column names or arrays with length equal to the length of the DataFrame. left_index − If True, use the index (row labels) from the left DataFrame as its join key(s). In case of a DataFrame with a MultiIndex (hierarchical), the number of levels must match the number of join keys from the right DataFrame. map accepts *args and "zips" them implicitly:. sums_list = sum(map(lambda *x:list(x), list1, list2), []) Although I guess that's actually clunkier :(Using sum to accumulate a list is slow, btw (sum is explicitly designed to reject strings because they have the same algorithmic problem. Jan 28, 2019 · Method #1 : Using list comprehension + zip () List comprehension does the task of concatenating the similar index elements. The task of zip function is concatenating the resultant string into a single list and return list. Jan 07, 2017 · 3 Ways to Element-Wise Sum Two Lists in Python ... Combinations of Different List Items - Duration: 8:32. Doug H 6,719 views. 8:32. 11 - More on Lists ( combine; nested; methods ) | Python ... Let's get the best of both worlds with variable length arguments. Variable-length arguments, varargs for short, are arguments that can take an unspecified amount of input. When these are used, the programmer does not need to wrap the data in a list or an alternative sequence. In Python, varargs are defined using the *args syntax. Dec 28, 2017 · The line c = a + b is used as a simple way to create a new list of the exactly the right length (at this stage, its contents are not important). The next two lines do the actual work of interleaving a and b : the first one assigns the elements of a to all the even-numbered indexes of c ; the second one assigns the elements of b to all the odd-numbered indexes of c . Reference all indexes in list and check for existence of value in python. I'm trying to create if block in my python3 script that checks if a value exists within a list I pull from JSONThe JSON data is below: Jan 10, 2018 · Second way to make pandas dataframe from lists is to use the zip function. We can use the zip function to merge these two lists first. In Python 3, zip function creates a zip object, which is a generator and we can use it to produce one item at a time. To get a list of tuples, we can use list() and create a list of tuples. Merge two Dataframes on index of one dataframe and some column of other dataframe. What if we want to merge two dataframe by index of first dataframe and on some column of second dataframe ? For example let’s change the dataframe salaryDfObj by adding a new column ‘EmpID‘ and also reset it’s index i.e. 1. Merging two Lists in Python: We can simply merge two lists using + operator like below. list1 = [10, 20, 30] list2 = [40, 50, 60] merged_list = list1 + list2 print("Merged List: ", merged_list) #It is also equivalent to above code using += list1 += list2 print("Merged List using +=: ", list1) The above solution internally creates a new list (merged_list) with a shallow copy of list1 and is concatenated with a shallow copy of list2. There are various methods to find and store the common elements from two lists. How to find the common elements in two lists in Python. To learn the various ways to find the common elements from two lists in Python. We have to make two separate lists. We will learn all the ways with an example. Using a function. Example 1: Make a function for ... Oct 22, 2019 · In this tutorial, I’ll show you how to concatenate and slice lists in Python. I’ll start with a simple concatenation of two lists, and then review the different ways to slice lists in Python. How to Concatenate Lists in Python. You can use the plus sign (‘+’) in order to concatenate lists in Python. Dec 28, 2017 · The line c = a + b is used as a simple way to create a new list of the exactly the right length (at this stage, its contents are not important). The next two lines do the actual work of interleaving a and b : the first one assigns the elements of a to all the even-numbered indexes of c ; the second one assigns the elements of b to all the odd-numbered indexes of c . Combining Python lists. If you have two lists that you want to combine into a single list, use the extend() function with the syntax: original_list.extend(additional_items_list) In your code, replace original_list with the name of the list to which you’ll be adding new list items. Python: merge two lists by putting their elements at alternate positions +2 votes . asked Apr 16, 2019 in Programming Languages by pythonuser (14.3k points) Let's get the best of both worlds with variable length arguments. Variable-length arguments, varargs for short, are arguments that can take an unspecified amount of input. When these are used, the programmer does not need to wrap the data in a list or an alternative sequence. In Python, varargs are defined using the *args syntax. There are various methods to find and store the common elements from two lists. How to find the common elements in two lists in Python. To learn the various ways to find the common elements from two lists in Python. We have to make two separate lists. We will learn all the ways with an example. Using a function. Example 1: Make a function for ... 1. Merging two Lists in Python: We can simply merge two lists using + operator like below. list1 = [10, 20, 30] list2 = [40, 50, 60] merged_list = list1 + list2 print("Merged List: ", merged_list) #It is also equivalent to above code using += list1 += list2 print("Merged List using +=: ", list1) The above solution internally creates a new list (merged_list) with a shallow copy of list1 and is concatenated with a shallow copy of list2. Oct 22, 2019 · In this tutorial, I’ll show you how to concatenate and slice lists in Python. I’ll start with a simple concatenation of two lists, and then review the different ways to slice lists in Python. How to Concatenate Lists in Python. You can use the plus sign (‘+’) in order to concatenate lists in Python. Jan 07, 2017 · 3 Ways to Element-Wise Sum Two Lists in Python ... Combinations of Different List Items - Duration: 8:32. Doug H 6,719 views. 8:32. 11 - More on Lists ( combine; nested; methods ) | Python ... Combining Python lists. If you have two lists that you want to combine into a single list, use the extend() function with the syntax: original_list.extend(additional_items_list) In your code, replace original_list with the name of the list to which you’ll be adding new list items.