standard-deviation

This question already has an answer here: Python: Numpy standard deviation error 3 answers 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? 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() : >>> np.std([0, 1], ddof=1) 0.70710678118654757 ddof modifies the divisor of the sum of the squares of the samples-minus-mean. The

I have several records with a given attribute, and I want to find the standard deviation. How do I do that? tolitius module Enumerable def sum self.inject(0){|accum, i| accum + i } end def mean self.sum/self.length.to_f end def sample_variance m = self.mean sum = self.inject(0){|accum, i| accum +(i-m)**2 } sum/(self.length - 1).to_f end def standard_deviation Math.sqrt(self.sample_variance) end end Testing it: a = [ 20, 23, 23, 24, 25, 22, 12, 21, 29 ] a.standard_deviation # => 4.594682917363407 01/17/2012: fixing "sample_variance" thanks to Dave Sag eprothro It appears that Angela may have

I want to plot a graph with the median of each row (not column!)(except values from the first column) with the standard deviation as errorbar. The result should look similar to that: I have a dataframe like this: myTable <- " 1 -50 -52 2 -44 -51 3 -48 -50 4 -50 -49 5 -44 -49 6 -48 -49 7 -48 -49 8 -44 -48 9 -49 -48 10 -48 -45 11 -60 -48 10 -50 -48 11 -80 -47" df <- read.table(text=myTable, header = TRUE) df <- c("ID","Value1","Value2"); My data is stored in a .csv file, which I load with the following line: df <- read.csv(file="~/path/to/myFile.csv", header=FALSE, sep=",") The code below

I'm trying to calculate the mean and standard deviation of several columns (except the first column) in a data.frame with NA values. I've tried colMeans , sapply , etc., to create a loop that runs through the data.frame and then stores means and standard deviations in a separate table but keep getting a "FUN" error. any help would be great. Thanks a sapply(df, function(cl) list(means=mean(cl,na.rm=TRUE), sds=sd(cl,na.rm=TRUE))) col1 col2 col3 col4 col5 means 3 8 12.5 18.25 22.5 sds 1.581139 1.581139 1.290994 1.707825 1.290994 as.data.frame( t(sapply(df, function(cl) list(means=mean(cl,na.rm

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 50 8 5 48 27 15 15 12 30 15 The lines below appear to do the job, but is terribly slow on my actual

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? trashgod ChartFactory.createHistogram() with an IntervalXYDataset such as HistogramDataset might be a suitable choice. HistogramDemo1 , seen among the statistical charts in the JWS demo , is an example. You can determine which

Is there some trick that would allow one to use bc (or some other standard utility) to return the standard deviation of an arbitrary number of numbers? For convenience, let's say that the numbers are stored in a Bash variable in the following way: myNumbers="0.556 1.456 45.111 7.812 5.001" So, the answer I'm looking for would be in a form such as the following: standardDeviation="$(echo "${myNumbers}" | <insert magic here>)" Using awk : standardDeviation=$( echo "$myNumbers" | awk '{sum+=$1; sumsq+=$1*$1}END{print sqrt(sumsq/NR - (sum/NR)**2)}' ) echo $standardDeviation Using perl : #!/usr/bin