histogram

问题 How can one plot the percentages as opposed to raw frequencies using the hist() function in R? 回答1: Simply using the freq=FALSE argument does not give a histogram with percentages, it normalizes the histogram so the total area equals 1. To get a histogram of percentages of some data set, say x, do: h = hist(x) # or hist(x,plot=FALSE) to avoid the plot of the histogram h$density = h$counts/sum(h$counts)*100 plot(h,freq=FALSE) Basically what you are doing is creating a histogram object,

问题 I'm trying to match the histograms of two images (in MATLAB this could be done using imhistmatch). Is there an equivalent function available from a standard Python library? I've looked at OpenCV, scipy, and numpy but don't see any similar functionality. 回答1: I previously wrote an answer here explaining how to do piecewise linear interpolation on an image histogram in order to enforce particular ratios of highlights/midtones/shadows. The same basic principles underlie histogram matching

问题 I'd like to label each bar of a histogram with either the number of counts in that bin or the percent of total counts that are in that bin. I'm sure there must be a way to do this, but I haven't been able to find it. This page has a couple of pictures of SAS histograms that do basically what I'm trying to do (but the site doesn't seem to have R versions): http://www.ats.ucla.edu/stat/sas/faq/histogram_anno.htm If possible, it would also be nice to have the flexibility to put the labels above

问题 Object fileButton = null; if("Analyze Text File".equals(command)) { JFileChooser filechooser; JFileChooser chooser = new JFileChooser(); int returnVal = filechooser.showOpenDialog(getParent()); if (returnVal == JFileChooser.APPROVE_OPTION) { File file = filechooser.getSelectedFile(); String Stext = (String) readFileAsString(file); //String text = textInput.getText(); Map<Integer, Integer> counts = getCounts(text); int width = counts.size() * BAR_WIDTH; int max = maxCount(counts); int height =

问题 I want to change the values on the x axis in my histogram in R. The computer currently has it set as 0, 20, 40, 60, 80, 100. I want the x axis to go by 10 as in: 0,10,20,30,40,50,60,70,80,90,100. I know to get rid of the current axis I have to do this (hist(x), .... xaxt = 'n') and then axis(side = 1) ..... But how do I get it to show the numbers that I need it to show? Thanks. 回答1: The answer is right there in ?axis ... dat <- sample(100, 1000, replace=TRUE) hist(dat, xaxt='n') axis(side=1,

问题 I have a list of strings: a = ['a', 'a', 'a', 'a', 'b', 'b', 'c', 'c', 'c', 'd', 'e', 'e', 'e', 'e', 'e'] I want to make a histogram for displaying the frequency distribution of the letters. I can make a list that contains the count of each letter using following codes: from itertools import groupby b = [len(list(group)) for key, group in groupby(a)] How do I make the histogram? I may have a million such elements in list a . 回答1: Very easy with Pandas . import pandas from collections import

问题 I have a dataset with some outliers, such as the following x <- rnorm(1000,0,20) x <- c(x, 500, -500) If we plot this on a linear x axis scale at this we see histogram(x) I worked out a nice way to put it on a log scale using this useful thread: how to use a log scale for y-axis of histogram in R? : mat <- data.frame(x) ggplot(ee, aes(x = xx)) + geom_histogram(colour="darkblue", size=1, fill="blue") + scale_x_log10() However, I would like the x axis labels from this 2nd example to match that

问题 Elsewhere on StackOverflow a question was asked regarding a depthbuffer histogram - Create depth buffer histogram texture with GLSL. I am writing an iOS image-processing app and am intrigued by this question but unclear on the answer provided. So, is it possible to create an image histogram using the GPU via GLSL? 回答1: Yes, it is. It's not clearly the best approach, but it's indeed the best one available in iOS, since OpenCL is not supported. You'll lose elegance, and your code will probably

问题 I'd like to create a bar graph where I change the color of some bars. The code for my bar graph is the following: y = [0.04552309, -0.001730885, 0.023943445, 0.065564478, 0.032253892, 0.013442562, ... -0.011172323, 0.024595622, -0.100614203, -0.001444697, 0.019383706, 0.890249809]; bar(y) I want the first six bars to be black and the last 6 bars to be blue, but I have no idea how to do it. 回答1: You need to plot them separately (but on the same axes): bar(1:6,y(1:6),'k') hold on bar(7:numel(y)

问题 I'd like to create a bar graph where I change the color of some bars. The code for my bar graph is the following: y = [0.04552309, -0.001730885, 0.023943445, 0.065564478, 0.032253892, 0.013442562, ... -0.011172323, 0.024595622, -0.100614203, -0.001444697, 0.019383706, 0.890249809]; bar(y) I want the first six bars to be black and the last 6 bars to be blue, but I have no idea how to do it. 回答1: You need to plot them separately (but on the same axes): bar(1:6,y(1:6),'k') hold on bar(7:numel(y)