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Articles by Nizamuddin Siddiqui
Page 93 of 196
How to combine two vectors while replacing the NA values with the values in the other vector in R?
Sometimes we have vectors with NA values, also there might be a situation that one of vector having an NA at a position and the other vector has the numerical values at the same position. For example, 1, 2, NA and 1, 2, 3. In this case, we might want to combine these two vectors to make a single vector. This can be done by using coalesce function of dplyr package.Example> library(dplyr) > x1 x1Output[1] NA 4 NA 1 2 NA 4 1 4 1 2 3 1 4 2 2 NA 2 2 1Example> y1 y1Output[1] 1 2 3 ...
Read MoreHow to add a citation in a plot created by using ggplot2 in R?
A footnote is generally used to give references to a document, text or image and it is called citation. It helps the reader or viewer to check out the original source using the new text or image is generated. If we want to give citation to a plot in R using ggplot2 package then we can add labs that has caption option to add the footnotes.ExampleConsider the below data frame −> set.seed(1) > x y df dfOutput x y 1 0.8735462 4.0117812 2 1.6836433 2.8898432 3 0.6643714 1.8787594 4 3.0952808 0.2853001 5 1.8295078 3.6249309 6 ...
Read MoreHow to find the column and row indices of values in a matrix using which function in R?
To find the row and column indices of values in a matrix, we cannot simply use which function because it returns the index based on sequence of the numbers in the matrix. For example, if we have a matrix M as below −1 2 3 4 1 6 7 8 1Now if we try to find the index using which(M==1) then it will return 1 5 9Because 1 is placed at 1, 5 and 9.Hence, we need to use arr.ind = TRUE so that the matrix can be read as an array by which function.ExampleConsider the below matrix −> M ...
Read MoreHow to find the number of distinct values in an R vector?
When we have repeated elements in an R vector and the vector size is large then we might want to know the distinct values in that vector. This will help us to understand the unique values we have in our vector, so that we can create the appropriate chart and perform the appropriate analysis using that vector. This can be done by using length function with unique.Examples> x1 x1Output[1] 2 5 5 3 2 4 3 3 1 4 5 4 5 3 3 1 1 2 5 1 3 2 4 1 3 1 5 4 2 5 5 ...
Read MorePython - Number of values greater than K in list
One of the basic problems for many complex problems is finding numbers greater than certain number in list in python, is commonly encountered.Example# find number of elements > k using for loop # initializing list test_list = [1, 7, 5, 6, 3, 8] # initializing k k = 4 # printing list print ("The list : " + str(test_list)) # using for loop to get numbers > k count = 0 for i in test_list : if i > k : count = count + 1 # printing the intersection print ("The numbers greater than 4 ...
Read MorePython - Prefix sum list
A list is a collection which is ordered and changeable. In Python lists are written with square brackets. You access the list items by referring to the index number. Negative indexing means beginning from the end, -1 refers to the last item. You can specify a range of indexes by specifying where to start and where to end the range. When specifying a range, the return value will be a new list with the specified items.Example# using list comprehension + sum() + list slicing # initializing list test_list = [3, 4, 1, 7, 9, 1] # printing original list print("The original ...
Read MorePython - Ways to convert array of strings to array of floats
String literals in python are surrounded by either single quotation marks, or double quotation marks. Assigning a string to a variable is done with the variable name followed by an equal sign and the string. You can assign a multiline string to a variable by using three quotes.Example# array of strings to array of floats using astype import numpy as np # initialising array ini_array = np.array(["1.1", "1.5", "2.7", "8.9"]) # printing initial array print ("initial array", str(ini_array)) # conerting to array of floats # using np.astype res = ini_array.astype(np.float) # printing final result print ("final array", str(res)) # array ...
Read MorePython - Ways to create triplets from given list
A list is a collection which is ordered and changeable. In Python lists are written with square brackets. You access the list items by referring to the index number. Negative indexing means beginning from the end, -1 refers to the last item. You can specify a range of indexes by specifying where to start and where to end the range. When specifying a range, the return value will be a new list with the specified items.Example# triplets from list of words. # List of word initialization list_of_words = ['I', 'am', 'Vishesh', 'and', 'I', 'like', 'Python', 'programming'] # Using list comprehension List ...
Read MorePython - Ways to find indices of value in list
Usually, we require to find the index, in which the particular value is located. There are many method to achieve that, using index() etc. But sometimes require to find all the indices of a particular value in case it has multiple occurrences in list.Example# using filter() # initializing list test_list = [1, 3, 4, 3, 6, 7] # printing initial list print ("Original list : " + str(test_list)) # using filter() # to find indices for 3 res_list = list(filter(lambda x: test_list[x] == 3, range(len(test_list)))) # printing resultant list print ("New indices list : " + str(res_list)) # ...
Read MorePython - Ways to flatten a 2D list
A list is a collection which is ordered and changeable. In Python lists are written with square brackets. You access the list items by referring to the index number. Negative indexing means beginning from the end, -1 refers to the last item. You can specify a range of indexes by specifying where to start and where to end the range. When specifying a range, the return value will be a new list with the specified items.Example# using chain.from_iterables # import chain from itertools import chain ini_list = [[1, 2, 3], [3, 6, 7], [7, 5, 4]] # ...
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