standard-deviation

问题 This question already has answers here : Python: Numpy standard deviation error (3 answers) Closed 4 years ago . Here is my code: import numpy as np print(np.std(np.array([0,1]))) it produces 0.5 I am confident that this is incorrect. What am I doing wrong? 回答1: By default, numpy.std returns the population standard deviation, in which case np.std([0,1]) is correctly reported to be 0.5 . If you are looking for the sample standard deviation, you can supply an optional ddof parameter to std() :

问题 I want to change all values of a row to zero if they are less than the standard deviation of that row. set.seed(007) X <- data.frame(matrix(sample(c(5:50), 100, replace=TRUE), ncol=10)) X1 X2 X3 X4 X5 X6 X7 X8 X9 X10 1 37 10 43 45 11 17 39 13 13 44 2 10 24 32 16 7 50 41 47 9 39 3 23 49 46 35 16 30 22 10 11 46 4 41 46 19 28 47 39 27 40 49 13 5 29 23 49 10 50 17 42 43 7 31 6 31 26 11 36 35 43 45 29 33 9 7 21 12 5 21 29 12 31 30 7 30 8 32 24 8 43 9 17 35 44 41 8 9 20 44 39 8 40 17 27 45 14 37 10

问题 I have a SQL below which is able to get the interval average of timestamp column grouped by icao_address, flight_number, flight_date. I'm trying to do the same for standard deviation and although I get a figure, it is wrong. The standard deviation that I get back is 14.06 (look at image below to see) while it should be around 1.8. Below is what I'm using for stddev calculation. STDDEV_POP(UNIX_SECONDS(timestamp))as standard_deviation Below is my SQL #standardSQL select DATE(timestamp) as

问题 I have a SQL below which is able to get the interval average of timestamp column grouped by icao_address, flight_number, flight_date. I'm trying to do the same for standard deviation and although I get a figure, it is wrong. The standard deviation that I get back is 14.06 (look at image below to see) while it should be around 1.8. Below is what I'm using for stddev calculation. STDDEV_POP(UNIX_SECONDS(timestamp))as standard_deviation Below is my SQL #standardSQL select DATE(timestamp) as

问题 I have a SQL below which is able to get the interval average of timestamp column grouped by icao_address, flight_number, flight_date. I'm trying to do the same for standard deviation and although I get a figure, it is wrong. The standard deviation that I get back is 14.06 (look at image below to see) while it should be around 1.8. Below is what I'm using for stddev calculation. STDDEV_POP(UNIX_SECONDS(timestamp))as standard_deviation Below is my SQL #standardSQL select DATE(timestamp) as

问题 I am trying to create a JTable that I can be able to click on a row and it will display a standard deviation curve. Here is what my JTable looks like right now. So for example, the standard deviation for the string screen saver, action->login, login->disclaimer, ok would look like this (I plotted it in excel) So my question is #1 is this possible and #2 if so then how? 回答1: ChartFactory.createHistogram() with an IntervalXYDataset such as HistogramDataset might be a suitable choice.

问题 I have the represented independently these two plots using R: #PLOT 1 x<-250:2500 #Hsap. Northern European a<-dnorm(x,1489,167) #Hsap. South African b<-dnorm(x,1472,142) plot(x,a, type="l", lwd=3, ylim=c(0,1.2*max(a,b,c)), ylab="Probability Density", xlab="Microns") lines(x,b, type="l", lwd=3, col="Red") PLOT 2 #CUSPAL ENAMEL FORMATION TIME x<-0:800 #Hsap. Northern European a<-dnorm(x,447,37) #Hsap. South African b<-dnorm(x,444,33) plot(x,a, type="l", lwd=3, ylim=c(0,1.2*max(a,b,c)), ylab=

问题 Solution I went with the solution provided by @thelatemail because I'm trying to stick with tidyverse and thus dplyr--I'm still new to R, so I'm taking baby steps and taking advantage of helper libraries. Thank you everyone for taking the time to contribute solutions. df_new <- df_inh %>% select( isolate, Phenotype, which( sapply( ., function( x ) sd( x ) != 0 ) ) ) Question I'm trying to select columns if the column name is "isolate" or "Phenotype" or if the standard deviation of the column

问题 I have an array of cartesian points (column 1 is x values and column 2 is y values) like so: 308 522 307 523 307 523 307 523 307 523 307 523 306 523 How would I go about getting a standard deviation of the points? It would be compared to the mean, which would be a straight line. The points are not that straight line, so then the standard deviation describes how wavy or "off-base" from the straight line the line segment is. I really appreciate the help. 回答1: If you are certain the xy data

问题 I have an array of cartesian points (column 1 is x values and column 2 is y values) like so: 308 522 307 523 307 523 307 523 307 523 307 523 306 523 How would I go about getting a standard deviation of the points? It would be compared to the mean, which would be a straight line. The points are not that straight line, so then the standard deviation describes how wavy or "off-base" from the straight line the line segment is. I really appreciate the help. 回答1: If you are certain the xy data