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Articles on Trending Technologies
Technical articles with clear explanations and examples
Unable to implement $addToSet in MongoDB to fetch values of a single field?
The $addToSet operator adds value to an array unless the value is already present, in which case $addToSet does nothing to that array.Let us create a collection with documents −> db.demo533.insertOne({"ProjectName":"Online Hospital Management"});{ "acknowledged" : true, "insertedId" : ObjectId("5e8b4cfaef4dcbee04fbbbfc") } > db.demo533.insertOne({"ProjectName":"Online Library Management"});{ "acknowledged" : true, "insertedId" : ObjectId("5e8b4d02ef4dcbee04fbbbfd") } > db.demo533.insertOne({"ProjectName":"Online Hospital Management"});{ "acknowledged" : true, "insertedId" : ObjectId("5e8b4d04ef4dcbee04fbbbfe") } > db.demo533.insertOne({"ProjectName":"Online Customer Tracker"});{ "acknowledged" : true, "insertedId" : ObjectId("5e8b4d0def4dcbee04fbbbff") }Display all documents from a collection with the help of find() method −> db.demo533.find();This will produce the following output −{ ...
Read MoreMongoDB query to fetch only the “Name” field based on roles?
For this, use aggregate(). Here, we have considered 3 roles − Admin, Guest, and User. Let us create a collection with documents −> db.demo532.insertOne({"Name":"Chris", "Type":"Admin"});{ "acknowledged" : true, "insertedId" : ObjectId("5e8b4a9def4dcbee04fbbbf9") } > db.demo532.insertOne({"Name":"David", "Type":"Guest"});{ "acknowledged" : true, "insertedId" : ObjectId("5e8b4aa3ef4dcbee04fbbbfa") } > db.demo532.insertOne({"Name":"Bob", "Type":"User"});{ "acknowledged" : true, "insertedId" : ObjectId("5e8b4ab0ef4dcbee04fbbbfb") }Display all documents from a collection with the help of find() method −> db.demo532.find();This will produce the following output −{ "_id" : ObjectId("5e8b4a9def4dcbee04fbbbf9"), "Name" : "Chris", "Type" : "Admin" } { "_id" : ObjectId("5e8b4aa3ef4dcbee04fbbbfa"), "Name" : "David", "Type" : "Guest" } { "_id" ...
Read MoreFind common elements in list of lists in Python
It is possible to have a list whose inner elements are also lists. In such cases we may come across a need when we have to find out the common elements among these inner lists. In this article we will find out the approaches to achieve this.With map and intersectionIntersection is a simple mathematical concept of finding the common elements between different sets. Python has the set method which returns a set that contains the similarity between two or more sets. So we first convert the elements of the list into set through a map function and then apply the ...
Read MoreConvert dictionary to list of tuples in Python
Converting from one collection type to another is very common in python. Depending the data processing needs we may have to convert the key value pairs present in a dictionary to pairs representing tuples in a list. In this article we will see the approaches to achieve this.With inThis is a straight forward approach where we just consider theExample Live DemoAdict = {30:'Mon', 11:'Tue', 19:'Fri'} # Given dictionary print("The given dictionary: ", Adict) # Using in Alist = [(key, val) for key, val in Adict.items()] # Result print("The list of tuples: ", Alist)OutputRunning the above code gives us ...
Read MoreCheck if two lists are identical in Python
In python data analysis, we may come across situation when we need to compare two lists and find out if they are identical meaning having same elements or not.Exmple Live DemolistA = ['Mon', 'Tue', 'Wed', 'Thu'] listB = ['Mon', 'Wed', 'Tue', 'Thu'] # Given lists print("Given listA: ", listA) print("Given listB: ", listB) # Sort the lists listA.sort() listB.sort() # Check for equality if listA == listB: print("Lists are identical") else: print("Lists are not identical")OutputRunning the above code gives us the following result −Given listA: ['Mon', 'Tue', 'Wed', 'Thu'] Given listB: ['Mon', 'Wed', 'Tue', 'Thu'] Lists are identicalWith ...
Read MoreCheck if list is strictly increasing in Python
Given a list, we may need to check for the sequence of its elements. In this article we will find out if the elements present in the list are in a strictly increasing order. Below programs achieve that objective.With all and zipIn this approach we first slice each element compare its value to the next element that is sliced. If all such comparisons hold true then we conclude the list is strictly in increasing order.Example Live DemolistA = [11, 23, 42, 51, 67] #Given list print("Given list : ", listA) # Apply all and range if (all(i < j for i, ...
Read MoreCheck if list is sorted or not in Python
Lists are the most widely used data collectios in python. We may come across situation when we need to know if the given list is already sorted or not. In this article we will see the approaches to achieve this.With sortWe take a copy of the given list, apply sort function to it and store that copy as a new list. Then we compare it with the original list and check if they are equal or not.Example Live DemolistA = [11, 23, 42, 51, 67] #Given list print("Given list : ", listA) listA_copy = listA[:] # Apply sort to copy listA_copy.sort() ...
Read MoreCheck if list contains consecutive numbers in Python
Depending on the needs of our data analysis we may need to check for presence of sequential numbers in a python data container. In the below programs we find out if among the elements of Alist, there are any consecutive numbers.With range and sortedThe sorted function will rearrange the elements of the list in a sorted order. We then apply the range function taking the lowest and highest numbers form the list using min and max functions. We store the results of above operations in two lists and compare them for equality.Example Live DemolistA = [23, 20, 22, 21, 24] sorted_list ...
Read MoreCheck if given string can be formed by concatenating string elements of list in Python
We sometimes need to check if a required string can be formed from many number of strings that are present in a list. It also should not matter in what order the strings are present in the list which have to be joined to get the required string.With permutationsFrom itertools we can use the permutations function which will give us the possible combinations of the strings in the list in various order. As soon as a given combination matches the required string, we conclude that the string can be formed.Example Live Demofrom itertools import permutations chk_str = 'balloon' Alist = ...
Read MoreCheck if given multiple keys exist in a dictionary in Python
During data analysis using python, we may need to verify if a couple of values exist as keys in a dictionary. So that the next part of the analysis can only be used with the keys that are part of the given values. In this article we will see how this can be achieved.With Comparison operatorsThe values to be checked are put into a set. Then the content of the set is compared with the set of keys of the dictionary. The >= symbol indicates all the keys from the dictionary are present in the given set of values.Example Live DemoAdict ...
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