histogram

问题 I am looking for a way to get a histogram of an image on the iPhone. The OpenCV library is way too big to be included in my app (OpenCV is about 70MB compiled), but I can use OpenGL. However, I have no idea on how to do either of these. I have found how to get the pixels of the image, but cannot form a histogram. This seems like it should be simple, but I don't know how to store uint8_t into an array. Here is the relevant question/answer for finding pixels: Getting RGB pixel data from CGImage

问题 I am trying to plot some histogrammed data on a polar axis but it wont seem to work properly. An example is below, I use the custom projection found How to make the angles in a matplotlib polar plot go clockwise with 0° at the top? it works for a scatter plot so I think my problem is with the histogram function. This has been driving me nuts all day, does anyone know what I am doing wrong........... import random import numpy as np import matplotlib.pyplot as plt baz = np.zeros((20)) freq =

问题 How can I convert an RGB histogram of an image to create a histogram showing the combined colors along with correct color wavelength range? Example code: pkg load image f=imread('/tmp/marbles.jpg'); f=uint8(f); %need to convert back to uint8 to show picture %Split into RGB Channels f_red = f(:,:,1); f_green = f(:,:,2); f_blue = f(:,:,3); %Get histValues for each channel [y_f_red, x] = imhist(f_red); [y_f_green, x] = imhist(f_green); [y_f_blue, x] = imhist(f_blue); subplot (2,1,1); imshow(f);

问题 gnuplot script: set auto x set yrange [0:100] set style data histogram set style histogram cluster gap 1 set style fill solid border -1 set boxwidth 1 plot 'test.data' using 1, '' u 2 test.data 80 15 71 81 81 71 61 75 57 17 80 80 82 91 86 73 output: I need so: How to reduce the gaps in the histogram gnuplot? 回答1: I think you cannot do this with the clustered histogram style, because the gap option takes only integer numbers. In your case with only two columns, you can use the boxes plotting

问题 I would like to plot the corresponding x for a given name. by that I mean, for foo it has to plot [10,20,30] in the form of a histogram and all foo, bar, baz need to be in the same graph.(I don't require 3d :) ) import pylab as P name = ['foo', 'bar', 'baz'] x = [[10,20,30],[40,50,60],[70,80,90]] P.figure() P.hist(x, 10, histtype='bar', color=['crimson', 'burlywood', 'chartreuse'], label=['Crimson', 'Burlywood', 'Chartreuse']) P.show() 回答1: Hope this helps you: from matplotlib import pyplot

问题 I have a data file with an undefined number of entries that looks like this: A B C D E.. 1 0 2 5 4 7 4 3 4 1 8 7 4 0 7 1 1 First row represents working time, than pause and so on in alternating fashion. To visualise this, I plot a columnstacked histograms from it by defining two linestyles with different colours and plotting it via: plot for [i=1:10] 'data.log' using i notitle But the problem is: I have to guess the max value of i. How can I get the number of columns the data file has? And

问题 I'm trying to create histogram from grouped data in pandas. So far I was able to create standard line plot. But I can't figure out how to do the same to get histogram (bar chart). I would like to get 2 age histograms of persons who survived Titanic crush and who didn't - to see if there is a difference in age distribution. Source data: https://www.udacity.com/api/nodes/5454512672/supplemental_media/titanic-datacsv/download So far my code: import pandas as pn titanic = pn.DataFrame.from_csv(

问题 Matplotlib's hist says "Compute and draw the histogram of x". I'd like to make a plot without computing anything first. I have the bin widths (unequal), and the total amount in each bin, and I want to plot a frequency-quantity histogram. For instance, with the data cm Frequency 65-75 2 75-80 7 80-90 21 90-105 15 105-110 12 It should make a plot like this: http://www.gcsemathstutor.com/histograms.php where the area of the blocks represents the frequency in each class. 回答1: Working on the same

问题 This question already has answers here : Exact number of bins in Histogram in R (5 answers) Closed last year . I've recently started using R and I don't think I'm understanding the hist() function well. I'm currently working with a numeric vector of length 296, and I'd like to divide it up into 10 equal intervals, and produce a frequency histogram to see which values fall into each interval. I thought hist(dataset, breaks = 10) would do the job, but it's dividing it into 12 intervals instead.

问题 Intro In gnuplot there's a solution to create histogram from file named hist.dat what likes 1 2 2 2 3 by using commands binwidth=1 set boxwidth binwidth bin(x,width)=width*floor(x/width) + binwidth/2.0 plot [0:5][0:*] "hist.dat" u (bin($1,binwidth)):(1.0) smooth freq with boxes that generates a histogram like this one from other SO page. Question How can I fit my function to this histogram? I defined a Gaussian function and initialized its values by f(x) = a*exp(-((x-m)/s)**2) a=3; m=2.5; s=1