# Find Closest Value In Array Python

Number of neighbors to get (default is the value passed to the constructor). k-Nearest Neighbors: Fit. If you want the None and '' values to appear last, you can have your key function return a tuple, so the list is sorted by the natural order of that tuple. Geometric Image Transformations¶ The functions in this section perform various geometrical transformations of 2D images. till N-th term Check if a number from every row can be selected such that xor of the numbers is greater than zero. ndim-levels deep nested list of Python scalars. Performance should be taken into consideration. asarray( array ) idx = (np. We're going to cover a few final thoughts on the K Nearest Neighbors algorithm here, including the value for K, confidence, speed, and the pros and cons of the algorithm now that we understand more about how it works. 5 >>> A = np. (Although it wasn't my intent, Python programers have told me this page has helped them learn Lisp. LeetCode - 3Sum Closest (Java) Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Hi, Say I have an array A with shape (10,3) and A[3,:] = [1,2,3] I want to find the index of the array in which I have these values [1,2,3]. numpy : argmin in multidimensional arrays. 47009242, 0. argmin() return array [idx] array stackoverflow. voltage on line 7, Python calls. and the closest distance depends on when and where the user clicks on the point. IndexOf static method. Combining both premium and delta into one model has been a challenge for me, but I always wanted to do a statistical approximation. 5 and beta < 0. This receives a Predicate parameter and returns a bool value indicating whether the element was found. Note that the value type must also match. Finding the index of an item given a list containing it in Python ; Is there a NumPy function to return the first index of something in an array? Accessing the index in 'for' loops? How do I sort a dictionary by value? Find nearest value in numpy array. Java Program to Find Smallest Element in Array. Plotly User Guide for Python. To find the closest match to a target value in a data column, use the INDEX, MATCH, ABS and the MIN function in Excel. We’ve spent a decent amount of time discussing the image classification in this module. I'm trying to tackle this problem via. Interview Top Interview Questions Easy Collection #. What's the easiest way to check whether an item is in a list and then get to that element and do something with it? So far I can think of Maybe, but in that case you are doing something to the list. metrics import euclidean_distances import util class PaletteQuery(object): """ Extract a L*a*b color array from a dict representation of a palette query. to solve the Closest pair of points problem in the planar case. Previous Next If you want to practice data structure and algorithm programs, you can go through data structure and algorithm interview questions. Originally, *12 - 6 was used to map the y value to the range of -6 and +6; but the "fade" did not happen fast enough or soon enough. org is available. Enter the elements of array as input. I'll leave that as an exercise for the student haha. If you don't know what lists are, you should definitely check Python list article. The most efficient solution I can think of is using binary search to find the index of number in the array, and then taking the neighboring elements based on minimum absolute difference. Our x vectors can be even not from our dataset we have worked with. I've got a little variation of the task: Change the first array at the positions indicated by the second array as follows: Replace the value by the maximum value of itself and its 4 closest neighbors. This tutorial is broken down into the following steps: Handle Data: Open the dataset from CSV and split into test/train datasets. 5 round to 0. The task is to find the closest value to the given number in array. Explanation: C3-F2 equals -39. Introduction to Dask. Tip: If you want to find all the matching elements based on a Predicate, FindAll is useful. asarray(condition). argmin() Simple. ISO 8601 distinguishes between a time interval, which is defined by two datetime endpoints, and a duration, which is the length of a time interval and can be defined by a unit of time such as '10 minutes'. Conor Neill Recommended for you. Given an array of sorted integers and find the closest value to the given number. Resizing an image means changing the dimensions of it, be it width alone, height alone or both. Then we find the nearest neighbours of new. VBA code to find closest number in range Is there a way of using code to find a number within a range that's closest to 10. zeros : Return a new array setting values to zero. 83500227, 0. You can find the index location on the grid of this by using the min function. 25 ( B[i+1,j] + B[i-1,j] + B[i,j+1] + B[i,j-1] ) without using nested for loops. till N-th term Check if a number from every row can be selected such that xor of the numbers is greater than zero. Python x in list can be used for checking if a value is in a list. I've got a little variation of the task: Change the first array at the positions indicated by the second array as follows: Replace the value by the maximum value of itself and its 4 closest neighbors. Currently, I will just try to post the accepted solutions. range searches and nearest neighbor searches). Play and Record Sound with Python¶. Use fancy indexing to extract the numbers. If there are regions in the image that should not be included in the sum, then the image could be masked before computing the sum. At first two lists are created with data points, one list will hold points which are sorted on x values, another will hold data points, sorted on y values. You can do this with the "str" function, or "unicode" function if you are working in Python 2 and want a Unicode string, or with format strings. 5 round to 2. 1) does not. num = 65 # Input number array = n. how do I find the closest value to a given number in an array? How do I find the closest array element to an arbitrary (non-member) number?. Now what i want is compare the string1 with all the strings in the list and return the nearest match for the string1 (i. The way I am going to. Next, we used the Python floor function inside the print statements to find the closest integer value of the above mentioned variable Difference between int and floor in Python This is one of the frequently asked question because, both the int and floor functions return the same result for positive values. The "math library" contains many methods to accomplish typical calculations or operations such as rounding. Next, I used the np. Each color is an instruction to carry out a certain movement. If there are less than 4 closest neighbors, take the maximum of the closest neighbors that are present. Welcome to the 8th part of our machine learning regression tutorial within our Machine Learning with Python tutorial series. Neighbors: Locate k most similar data instances. Find closest number in array. Parameters. map() function, we take all of our Y values and insert them into a new Array of Numbers. returns the index in the flatten array, which is coordinates of the min value in it. Please note that AF SDK and PI Web API are mature Developer Technologies which should be preferred upon PI SDK. ind: array. It aims to provide a 1:1 Python port of Richard Schreier’s *excellent* MATLAB Delta Sigma Toolbox, the de facto standard tool for high-level delta sigma simulation, upon which it is very heavily based. it's straightforward to use binary research. On the other hand the closest 5 are all A and this should count more. walk and lots of updates to the workspace environment. Note that the return value from the fmin function is a numpy array which – for the example above – contains only one number as we have only one parameter (here x) to vary. Note that it is the kth largest element in the sorted order, not the kth distinct element. Indices of the nearest points in the population matrix. A Simple Solution is to use two nested loops. This pairing causes ties in absolute value to be broken by initial value. This is most important when developing things like financial software, so you'll want to check the rules of local law for rounding. partition takes an array and a number K; the result is a new array with the smallest K values to the left of the partition, and the remaining values to the right, in. Returns: dist: array. Introduction ¶. 7x specifically. The centroid is simply the mean of all of the examples currently assigned to the cluster. C Program to Find Largest Element in an Array This program takes n number of element from user (where, n is specified by user) and stores data in an array. max_lt([2, 3, 5, 7, 11], 6) would be 5, because 5 is greatest value in the list which is also less than 6. insert() assuming that a is already sorted. Is there a numpy-thonic way, e. python - Find nearest value in numpy array - Stack Overflow import numpy as np def find_nearest ( array , value ): array = np. For values exactly halfway between rounded decimal values, NumPy rounds to the nearest even value. abs(arr - v)). The only catch is, this requires some hardware that doesn't exist (yet), namely a quantum computer. First up, the vertex shader program, which will place a rectangle in our 3D world for the background image. We have been using Python lists throughout the book — recall that we use Python lists as arrays because they support the four core array operations: creation, indexed access, indexed assignment, and iteration. This pairing causes ties in absolute value to be broken by initial value. For now, we’ll just handle a single image from the left-hand side webcam. Here: We see successful calls to Array. Python program to use pi value as global variable in your program to print the area of circle. k -Nearest Neighbors algorithm (or k-NN for short) is a non-parametric method used for classification and regression. The values appear 10 per line and are comma separated. StructType, it will be wrapped into a pyspark. From searching around I realized that cKDTree query is going to help me with nearest neighbor search. It aims to provide a 1:1 Python port of Richard Schreier’s *excellent* MATLAB Delta Sigma Toolbox, the de facto standard tool for high-level delta sigma simulation, upon which it is very heavily based. int index=Array. In this section, we will consider in detail two classical algorithms for sorting and searching—binary search and mergesort—along with several applications where their efficiency plays a critical role. You are given as input an unsorted array of n distinct numbers, where n is a power of 2. You can do this with the "str" function, or "unicode" function if you are working in Python 2 and want a Unicode string, or with format strings. argmin (a[, axis, out]) Returns the indices of the minimum values along an axis. More, precisely, the k is the number of nearest neighbors you wish to take a vote from when classifying a new data point. How to normalize and standardize time series data using scikit-learn in Python. Depends if you want to round up, down, or automatically: Rounding up or down with Floor and ceiling functions In Python those are attributes you'd import from the math module. ceil_exact (val, flt_type) Return nearest exact integer >= val in float type flt_type. Definition and Usage. # import cmath def find_perfect_square_count (a, b, verbose = False): ''' The strategy here is not to iterate through the set of possible integer values and check for is_perfect_square() each time but to translate the upper and lower values to. MAX_VALUE which is the largest value an integer variable can have! Find Smallest Number in an Array Using Java. The target needs to be a single column with the same number of observations as the feature data. This approach applies the same method but using numpy module. There is a workaround but it's quite a bit of work: Write a sort algorithm which sorts the array and (at the same time) updates a second array which tells you where this entry was before the array was sorted. 6 for Python 2. Return the indexes of the first number and. Assumes array is sorted in ascending order function binary-search(value, array A[1. In the previous tutorial, we began structuring our K Nearest Neighbors example, and here we're going to finish it. Then I will segue those into a more practical usage of the Python. Values with a NaN value are ignored from operations like sum, count, etc. k-Nearest Neighbors: Fit. The C++ program is successfully compiled and run on a Linux system. max_lt([2, 3, 5, 7, 11], 6) would be 5, because 5 is greatest value in the list which is also less than 6. Performance should be taken into consideration. nanmax The maximum value of an array along a given axis, ignoring any NaNs. 5 and beta < 0. Learning the values of $\mu_{c, i}$ given a dataset with assigned values to the features but not the class variables is the provably identical to running k-means on that dataset. : closestToZero. We start from a naive implementation of divide-and-conquer approach to the closest pair of points problem: Let us suppose that we have 2 lists of size n as our inputs: x and y, which correspond to. Given a non-empty binary search tree and a target value, find the value in the BST that is closest to the target. python program to use local variable by taking user input and print nearest power of 3. If you want multiple to find multiple occurrences of an element, use the lambda function below. More, precisely, the k is the number of nearest neighbors you wish to take a vote from when classifying a new data point. Looking for a value in a list - Python In any scripting language, avoiding loops makes for easier to write and faster to run code. Sometimes it is useful to know what is the smallest value in a sequence greater than (or equal to) some other value. ceil(data) array([[ 1. Tutorial: K Nearest Neighbors in Python In this post, we'll be using the K-nearest neighbors algorithm to predict how many points NBA players scored in the 2013-2014 season. Harder one: Generate a 10 x 3 array of random numbers (in range [0,1]). Where we left off, we had just realized that we needed to replicate some non-trivial algorithms into Python code in an attempt to calculate a best-fit line for a given dataset. Since array is the default in NumPy, some functions may return an array even if you give them a matrix as an argument. In the above program, we've used a non-primitive data type String and used Arrays's stream() method to first convert it to a stream and anyMatch() to check if array contains the given value toFind. X as well as Python 2. The reason you are getting a negative when you do [5 2 1] is because 2-5 is -3 and less than 2-1 which is 1. Sometimes it is useful to know what is the smallest value in a sequence greater than (or equal to) some other value. When the swap function is called, it creates local variables (also called a and b in this case) and trades their values. (If our value is greater than 32 then output will be 5 because 2 5 = 32) Java Programming provides two different functions to find the closest exponent of the specified value. In this article you will learn about a very simple yet powerful algorithm called KNN or K-Nearest Neighbor. The array is sorted. Upgrade your Python skills: Examining the Dictionary Photo by Romain Vignes on Unsplash a hash table (hash map) is a data structure that implements an associative array abstract data type, a structure that can map keys to values. You can help. k -Nearest Neighbors algorithm (or k-NN for short) is a non-parametric method used for classification and regression. As mentioned in the earlier sections, the generation of anomalies within data directly depends on the generation of the data points itself. When marks are arranged in the increasing order, we get {7,9. In this section, we will consider in detail two classical algorithms for sorting and searching—binary search and mergesort—along with several applications where their efficiency plays a critical role. c2 – A D x N array with coordinate values (either as floats or AngularPosition objects) or a sequence of LatLongCoordinates objects for the second set of coordinates. ceil() function rounds every value in the array to the nearest integer greater than or equal to the original value: >>> np. How to impute missing class labels using nearest neighbours in Python? with categorical feature X = np. Learn how to find the best K value and plot the accuracies for various K values. array ( matrix with missing values in the. 6 for Python 2. and I want to find the name of the nearest point in gpd2 for each row in gpd1: desired_output = Name ID geometry Nearest 0 John 1 POINT (1 1) Home 1 Smith 1 POINT (2 2) Shops 2 Soap 1 POINT (0 2) Work I've been trying to get this working using a lambda function:. Python Interpolate. Arrays and lists are both used in Python to store data, but they don't serve exactly the same purposes. Then do a Min-Max on the distance squared array to find the index of minimum distance. Returns: dist: array. Now, we begin with a numpy. - Euclidean distance computes the distance between two objects using the Pythagorean Theorem. My objective is to build an N-dimensional array in Python that has the mean of the intersection of a number of features. The function follows the System V AMD64 calling convention (standard on Gnu/Unix systems), such that the sole parameter ( n ) is passed in the EDI register, and the result is returned in the EAX register. By 'closeness statistics' I mean statistics giving information about how close the objects are to each other. Over the next 10 years, many scientific programming communities began doing array programming in Python, but the library ecosystem had become fragmented in the early 2000s. Here, instead of images, OpenCV comes with a data file, letter-recognition. The values appear 10 per line and are comma separated. OpenCV is the most comprehensive open-source Library for computer vision. For values exactly halfway between rounded decimal values, NumPy rounds to the nearest even value. The path information. and want to round so the values are print Test [1,2,4]. We're going to cover a few final thoughts on the K Nearest Neighbors algorithm here, including the value for K, confidence, speed, and the pros and cons of the algorithm now that we understand more about how it works. From searching around I realized that cKDTree query is going to help me with nearest neighbor search. If you were optimising our script for efficiency. For example, I have the number of customers in a store at any given time. array ( matrix with missing values in the. You want to find the E24/E48/E96 resistor value that is closest to a given exact value programmatically using python. If the given schema is not pyspark. They are extracted from open source Python projects. as plt from skimage import measure # Find contours at. In this tutorial, we shall the syntax of cv2. distance squared array = (A-B)^2. ui in your code is: from PyQt4 import QtCore, QtGui, uic class MyWidget(QtGui. Note: If the difference is same for two values print the value which is greater than the given number. The "math library" contains many methods to accomplish typical calculations or operations such as rounding. Data Normalization or standardization is defined as the process of rescaling original data without changing its behavior or nature. We will find the smallest distance from the strip array. The array_values() function returns an array containing all the values of an array. Java Program to Find Smallest Element in Array. zeros array that is the length of the lexicon. So if I go into QtDesigner and build a UI, it’ll be saved as a. min())[0] # If you want the index of the element of array (array) nearest to the the given number (num) nearest_val = array[abs(array-num)==abs(array-num). And using that INDEX returns the value at index 7. If not found, it returns -1. The GlyphSeparationHook is a python routine which FontForge will call when it wants to figure out the optical separation between two glyphs. ceil(data) array([[ 1. They can refer to different values, and changing one does not affect the other. The next two versions accept either a float or a decimal. You can vote up the examples you like or vote down the ones you don't like. Finding the index of an item given a list containing it in Python ; Is there a NumPy function to return the first index of something in an array? Accessing the index in 'for' loops? How do I sort a dictionary by value? Find nearest value in numpy array. numpy : argmin in multidimensional arrays. Defaults to True. Find twice the value of each element of the array in two different ways: (i) using addition and (ii) using multiplication. This is the program to find closest pair of points in an array. How to Find all Pairs in Array of Integers Whose sum is Equal to a Given Number - Java Solution Practising coding problems are very important to do well in any programming interview. In Python we frequently need to check if a value is in an array (list) or not. Masked arrays are arrays that may have missing or invalid entries. python,mongodb,pymongo Insert only accepts a final document or an array of documents, and an optional object which contains additional options for the collection. We need to find the closest value to the given number. The *8-1 comes from experimenting with different values to see what looked good. Closest Pair in Python. We can use these peak values to isolate corners and edges as I will describe in the next step. Neighbors: Locate k most similar data instances. If you want multiple to find multiple occurrences of an element, use the lambda function below. Resizing an image means changing the dimensions of it, be it width alone, height alone or both. max(), but that function returns only the greater of two values. Is there a numpy-thonic way, e. You can use any aggregator function such as average, mean, max, min, etc. How to normalize and standardize time series data using scikit-learn in Python. The minimum value of an array along a given axis, propagating any NaNs. Currently, the library supports k-Nearest Neighbors based imputation and Random Forest based imputation (MissForest) but we plan to add other. We can calculate arbitrary percentile values in Python using the percentile() NumPy function. So, now our network is trained, and we can start clustering. Here, instead of images, OpenCV comes with a data file, letter-recognition. By 'closeness statistics' I mean statistics giving information about how close the objects are to each other. Python – List & Operations Posted on September 30, 2016 by go2analytics • Posted in list , Python • Tagged list • Leave a comment List append() Method. ndim-levels deep nested list of Python scalars. In order to use the code in a module, Python must be able to locate the module and load it into memory. walk and lots of updates to the workspace environment. We will be making use of binary search to solve this problem. If there are less than 4 closest neighbors, take the maximum of the closest neighbors that are present. Other Processing. Currently, the library supports k-Nearest Neighbors based imputation and Random Forest based imputation (MissForest) but we plan to add other. com site search: "k-NN is a type of instance-based learning , or lazy learning , where the function is only approximated locally and all computation is deferred until classification. To do this, you need to find the array index of the element that has the value closest to v, like so: idx = (np. Hi All, Can you give me some hints (code snippet in Arcpy or ArcObject) on: for a given point to find the closest point location on a line. They are extracted from open source Python projects. and I want to find the name of the nearest point in gpd2 for each row in gpd1: desired_output = Name ID geometry Nearest 0 John 1 POINT (1 1) Home 1 Smith 1 POINT (2 2) Shops 2 Soap 1 POINT (0 2) Work I've been trying to get this working using a lambda function:. find_nearest( array, value ). Note: The first character is denoted by a value of 0 (not 1): A value of 0 means that the entire string is searched. We can see that the figure that we're plotting with py. A connectivity value of 8 means that the eight nearest neighbor pixels (those that share a corner) will be considered. The function follows the System V AMD64 calling convention (standard on Gnu/Unix systems), such that the sole parameter ( n ) is passed in the EDI register, and the result is returned in the EAX register. Python script to determine optimal resistor combinations. Finding Maximum/Minimum Value in an Array by kirupa | 1 July 2005. Arrays and lists are both used in Python to store data, but they don't serve exactly the same purposes. Eliminate Python overhead. insert() assuming that a is already sorted. If we want find the one number closest to x, we don't have to check one by one. Here is a quick example: a = ["1", "2", "3"] if "2" in a: print "string 2 is in array a" else: print "string 2. The first axis of such an array is the samples axis and the second one is the features axis. The array_values() function returns an array containing all the values of an array. k-Nearest Neighbors: Fit. Can anyone suggest an efficient way to determine the array location of the nearest element whose value is less than the search element?. Next we need a function to compute the centroid of a cluster. Do not worry if you don't know what these are yet; we will explain what they are when we need them later. The array may contain duplicate values and negative. You could do this in-place using the isnull() method as a mask, but because it is such a common operation Pandas provides the fillna() method, which returns a copy of the array with the null values replaced. The above bytes of code define a function in 64-bit x86 machine code that finds the closest Fibonacci number to the specified input value, n. Array may contain duplicate values and negative numbers. 4) Examine the results list to find those points that were within the specified distances of the search origins. Return value from round() The round() method returns: (If ndigits not provided) nearest integer to the given number If two multiples are really close, rounding is done toward the even choice (If ndigits given) floating point number rounded off to the ndigits digits Always rounded to the closest multiple of 10 to the power minus ndigits. Use these codes as a reference library or simply copy and paste into your own applications. We can calculate arbitrary percentile values in Python using the percentile() NumPy function. Finding nearest point of a. This is a Java Program to Find the Largest Number in an Array. The function does not return any values and does not alter a or b outside of its local copy. python min index numpy. Generally, to find a value in unsorted array, we should look through elements of an array one by one, until searched value is found. 5) are 0, and round(1. StructType as its only field, and the field name will be “value”, each record will also be wrapped into a tuple, which can be converted to row later. The problem is: given a dataset D of vectors in a d-dimensional space and a query point x in the same space, find the closest point in D to x. Use abs and argsort to find the column j closest for each row. It's easy to find the value given a key to a python dictionary: lValue = lDictionary [ lKey ] If you want to do the reverse, and find the value for a given key, it's possible by using a list comprehension:. As we are looking for the index of the specific value we need to filter the potential indexes of all the elements. Using the built in Array. I need to find the index of the closest element in 'aRef' for all elements in 'aTest'. python,mongodb,pymongo Insert only accepts a final document or an array of documents, and an optional object which contains additional options for the collection. 5 and beta < 0. argmin() return array [idx] array stackoverflow. Whatever the goal, Python’s design makes the programming experience feel almost as natural as writing in English. The second and third nearest neighbors are [2,1], [-1,-1], whose classes are 0, 1. This interval would be used in an IVT problem where the intervals will be be part of [a,b] and will be used to compute the output of the initial input. To break it down: I read in the file with csv. argmax Return the indices of the maximum values. I have the following function to accomplish this task: import math def. You are given as input an unsorted array of n distinct numbers, where n is a power of 2. asarray(condition). Hello Brian, PI SDK is announced to become deprecated but I was able to find some resources about how to retrieve data from PI using Python. Even if not, as long as you don't need to sort before every time you call take_closest, the bisect module will likely come out on top. First up, the vertex shader program, which will place a rectangle in our 3D world for the background image. We start from a naive implementation of divide-and-conquer approach to the closest pair of points problem: Let us suppose that we have 2 lists of size n as our inputs: x and y, which correspond to. Explore Channels Plugins & Tools Pro Login About Us. Returns the sorted unique elements of an array. org Mailing Lists: Welcome! Below is a listing of all the public Mailman 2 mailing lists on mail. This preprocessing can be useful for sparse datasets (lots of zeros) with attributes of varying scales when using algorithms that weight input values such as neural networks and algorithms that use distance measures such as K-Nearest Neighbors. e harish in example) I tried LevenshteinDistance algorithm but it is different we need to pass two strings and it will return how many characters changed, but in my case it is totally different. Python program to use pi value as global variable in your program to print the area of circle. find_nearest( array, value) Code Examples. More than a HOWTO, this document is a HOW-DO-I use Python to do my image processing tasks. Python program to use pi value as global variable in your program to print the area of circle. 5 # upper left corner |. Record the indices of the elements in target_array that are within tolerance, tol, of their closest match. The first axis of such an array is the samples axis and the second one is the features axis. Ḣ Retrieve the first index, which corresponds to the smallest value. Find Closest Value in Array This is a formula that is used to compare the market value of a particular job against the midpoints in a grade structure. In the above program, we've used a non-primitive data type String and used Arrays's stream() method to first convert it to a stream and anyMatch() to check if array contains the given value toFind. But thatt's more about where the function is defined, in contrast to where in the code it is called (or perhaps even declared, though I don't think that applies to Python). Given an array of sorted integers and find the closest value to the given number. lower_blue = np. I have the following function to accomplish this task: import math def. Often when faced with a large amount of data, a first step is to compute summary statistics for the data in question. Another way to use. argmin() Simple. If so, find immediately returns the value of that element. In the process, we learned how to split the data into train and test dataset. missingpy is a library for missing data imputation in Python. We retrained the TensorFlow object detection API on Bosch dataset to detect traffic lights and we used the KD-Tree algorithm to efficiently find the point in a set that is nearest to a given input point. I've got a little variation of the task: Change the first array at the positions indicated by the second array as follows: Replace the value by the maximum value of itself and its 4 closest neighbors. My objective is to build an N-dimensional array in Python that has the mean of the intersection of a number of features. If there are regions in the image that should not be included in the sum, then the image could be masked before computing the sum. The returned insertion point i partitions the array a into two halves so that all(val < x for val in a[lo:i]) for the left side and all(val >= x for val in a[i:hi]) for the right side. The task is to find the closest value to the given number in array. You can vote up the examples you like or vote down the ones you don't like. Given a non-empty binary search tree and a target value, find the value in the BST that is closest to the target. Python: Find the closest value (to a given scalar) in an array.