histogram | 易学教程

How does one plot a 3D stacked histogram in R?

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问题 I want to plot stacked histograms in R; i.e. stack individual histograms in the third dimension. thank you all for your suggestions, especially the one by Shane. @hadley, I agree with your points, however, my situation is different: the main point I'm trying to convey by plotting four stacked histograms is that the tails vary significantly....the part that will get obscured is of no consequence in the data I'm presenting....also, being able to read the frequency axis is also not important

Change histogram bar colours greater than a certain value

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问题 So far, I've managed to change the colour a single bar in a histogram following the example here test <- rnorm(100); h <- hist(test); b <- cut(1, h$breaks); clr <- rep("grey", length(h$counts)); clr[b] <- "red"; plot(h, col=clr); I want to be able to change the colour of histogram bins that are above a certain x-axis value - e.g. that are above 1 in the distribution function in the example. Part of the reason why I am having trouble is that I don't exactly understand the factor that cut()

Finding the local maxima/peaks and minima/valleys of histograms

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问题 Ok, so I have a histogram (represented by an array of ints), and I'm looking for the best way to find local maxima and minima. Each histogram should have 3 peaks, one of them (the first one) probably much higher than the others. I want to do several things: Find the first "valley" following the first peak (in order to get rid of the first peak altogether in the picture) Find the optimum "valley" value in between the remaining two peaks to separate the picture I already know how to do step 2

Gnuplot change color of bars in histogram

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问题 is it possible to change the color of bars in a Gnuplot script dynamically? I have the following script reset fontsize = 12 set term postscript enhanced eps fontsize set output "bargraph_speedup.eps" set style fill solid 1.00 border 0 set style histogram set style data histogram set xtics rotate by -45 set grid ytics linestyle 1 set xlabel "Benchmarks" font "bold" set ylabel "Relative execution time vs. reference implementation" font "bold" set datafile separator "," plot 'bm_speedup.dat'

How to compute “EMD” for 2 numpy arrays i.e “histogram” using opencv?

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Since I'm new to opencv, I don't know how to use the cv.CalcEMD2 function with numpy arrays. I have two arrays: a=[1,2,3,4,5] b=[1,2,3,4] How can I transfer numpy array to CVhistogram and from Cvhistogram to the function parameter signature ? I would like anyone who answers the question to explain any used opencv functions through the provided solution. "EMD" == earth mover's distance . Update:- also ,It will be helpful if anyone can tell me how to set the cv.CalcEMD2 parameter i.e "signature" using numpy array!! Note:- * For those who may be interested in this question ,This answer needs more

R- split histogram according to factor level

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问题 This is my data: type<-rep(c(0,1),100) diff<-rnorm(100) data<-data.frame(type,diff) If I want to plot historgram of diff , I do this: hist(data$diff) But what I want to do to split my histogram according to type . I could do this: par(mfrow=c(1,2)) hist(data$diff[data$type==0]) hist(data$diff[data$type==1]) But what this is giving me are two different histograms side by side. What I want to do is produce a single histogram with diff of 0 at one side and diff of 1 at other side. Something like

Circular Histogram for Python

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问题 I have periodic data and the distribution for it is best visualised around a circle. Now the question is how can I do this visualisation using matplotlib? If not, can it be done easily in Python? My code here will demonstrate a crude approximation of distribution around a circle: from matplotlib import pyplot as plt import numpy as np #generatin random data a=np.random.uniform(low=0,high=2*np.pi,size=50) #real circle b=np.linspace(0,2*np.pi,1000) a=sorted(a) plt.plot(np.sin(a)*0.5,np.cos(a)*0

gnuplot, break y-axis in two parts

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I have a histogram with some small values and some very big values. How can I break the y-axis in two parts? EDIT: gnuplot sample: set style histogram columnstacked set style data histograms set key autotitle columnheader plot for [i=2:6] 'test.dat' using i test.dat: action device1 device2 device3 load 200 203 190 2 4 process 3 9 6 7 3 save 4 2 7 4 3 My answer is based on the example and comment on this website . In essence, you are looking for a broken y-axis , which can be achieved using the multiplot option: reset unset key bm = 0.15 lm = 0.12 rm = 0.95 gap = 0.03 size = 0.75 kk = 0.5 #

How to make variable bar widths in ggplot2 not overlap or gap

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geom_bar seems to work best when it has fixed width bars - even the spaces between bars seem to be determined by width, according to the documentation . When you have variable widths, however, it does not respond as I would expect, leading to overlaps or gaps between the different bars (as shown here ). To see what I mean, please try this very simple reproducible example: x <- c("a","b","c") w <- c(1.2, 1.3, 4) # variable widths y <- c(9, 10, 6) # variable heights ggplot() + geom_bar(aes(x = x, y = y, width = w, fill=x), stat="identity", position= "stack") What I really want is for the

Difference between contrast stretching and histogram equalization

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问题 I would like to know the difference between contrast stretching and histogram equalization . I have tried both using OpenCV and observed the results, but I still have not understood the main differences between the two techniques. Insights would be of much needed help. 回答1: Lets Define Contrast first, Contrast is a measure of the “range” of an image; i.e. how spread its intensities are. It has many formal definitions one famous is Michelson’s: He says contrast = ( Imax - Imin )/( Imax + I min