min

来源： https://stackoverflow.com/questions/32354695/limit-result-of-subtraction-to-a-minimum-of-zero

问题 Please consider the following: I recently 'discovered' the awesome plyr and dplyr packages and use those for analysing patient data that is available to me in a data frame. Such a data frame could look like this: df <- data.frame(id = c(1, 1, 1, 2, 2), # patient ID diag = c(rep("dia1", 3), rep("dia2", 2)), # diagnosis age = c(7.8, NA, 7.9, NA, NA)) # patient age I would like to summarise the minimum patient age of all patients with a median and mean. I did the following: min.age <- df %>%

问题 I want to subtract the values in a vector from a scalar. However, if the result is lower than zero I want to set the result to zero. I have tried using max , but it doesn't give me the expected result s # [1] 750.0 975.0 1125.0 1237.5 1312.5 1400.0 max(1050 - s, 0) # [1] 300 I expect result to be c(300, 150, 0, 0, 0, 0) 回答1: I suggest pmax : pmax(1050 - s, 0) # [1] 300 75 0 0 0 0 来源： https://stackoverflow.com/questions/3438049/constrain-lower-limit-of-the-result-of-a-subtraction

问题 I have a function and I would like to find its maximum and minimum values. My function is this: def function(x, y): exp = (math.pow(x, 2) + math.pow(y, 2)) * -1 return math.exp(exp) * math.cos(x * y) * math.sin(x * y) I have an interval for x [-1, 1] and y [-1, 1]. I would like to find a way, limited to this interval, to discover the max and min values of this function. 回答1: Using, for instance, scipy 's fmin (which contains an implementation of the Nelder-Mead algorithm), you can try this:

问题 What am I missing in this code here so that it sets min1 and min2 to the two smallest numbers? def test() : # do not change this line! list = [4, 5, 1, 9, -2, 0, 3, -5] # do not change this line! min1 = list[0] min2 = list[1] #missing code here print(min1, min2) return (min1, min2) # do not change this line! # do not write any code below here test() # do not change this line! # do not remove this line! 回答1: List does not sort elements in it implicitly. You have sort the list with sort()

问题 Consider Below 2 examples. 1 With Streams myList.stream().map(this::getInt).max(Integer::compareTo); 2 Old way int max = Integer.MIN_VALUE; for (MyItem item : myList) { max = Math.max(max, getInt(item)); } Above getInt method accepts a MyItem argument and returns an int result. Here, #2 gives me a much lower latency compared to #1. Does anyone have an idea why or anything going wrong for me? 回答1: myList.stream().mapToInt(this::getInt).max() Try mapping to an IntStream. An IntStream works with

问题 Consider Below 2 examples. 1 With Streams myList.stream().map(this::getInt).max(Integer::compareTo); 2 Old way int max = Integer.MIN_VALUE; for (MyItem item : myList) { max = Math.max(max, getInt(item)); } Above getInt method accepts a MyItem argument and returns an int result. Here, #2 gives me a much lower latency compared to #1. Does anyone have an idea why or anything going wrong for me? 回答1: myList.stream().mapToInt(this::getInt).max() Try mapping to an IntStream. An IntStream works with

问题 SO already has multiple questions related to this topic. My question ain't 'bout the algorithm. It's 'bout sorting the final possibilities vector as per profit I wrote the following piece of code to solve the 0/1 knapsack problem: #include "algorithms.h" struct Item { int index = 1; int profit = 1; int weight = 1; Item() = delete; explicit Item(int i, int _profit, int w) { index = i; profit = _profit; weight = w; } bool operator<(const Item& item) { return this->profit < item.profit; } bool

问题 How do I return a list of the 3 lowest values in another list. For example I want to get the 3 lowest values of this list: in_list = [1, 2, 3, 4, 5, 6] input: function(in_list, 3) output: [1, 2, 3] 回答1: You can use heapq.nsmallest: >>> from heapq import nsmallest >>> in_list = [1, 2, 3, 4, 5, 6] >>> nsmallest(3, in_list) [1, 2, 3] >>> 回答2: If you could sort,you can get frst 3 elements as below: alist=[6, 4, 3, 2, 5, 1] sorted(alist)[:3] Output: [1,2,3] 回答3: even simpler without modules

问题 How do I return a list of the 3 lowest values in another list. For example I want to get the 3 lowest values of this list: in_list = [1, 2, 3, 4, 5, 6] input: function(in_list, 3) output: [1, 2, 3] 回答1: You can use heapq.nsmallest: >>> from heapq import nsmallest >>> in_list = [1, 2, 3, 4, 5, 6] >>> nsmallest(3, in_list) [1, 2, 3] >>> 回答2: If you could sort,you can get frst 3 elements as below: alist=[6, 4, 3, 2, 5, 1] sorted(alist)[:3] Output: [1,2,3] 回答3: even simpler without modules