histogram

I would like to plot a 2D histogram that includes both positive and negative numbers. I have the following code which uses pcolormesh but I am unable to specify the color levels to force the white color to corresponds to zero (i.e., I want my colorbar to be symmetric around zero). I've also tried imshow. I know you can specify colour levels in plt.contour and plt.contourf but I can't find a way to plot the 2D histogram using blocks. Any advice would be greatly appreciated. import numpy as np import matplotlib.pyplot as plt from matplotlib import cm as CM fig = plt.figure() # create an example

I am working on a project in which the two images will be checked for similarity like 'Google Image Search by image'. I searched through Google and also on various sites including stackoverflow and learnt about various techniques like histogram, sift, fourier transform, pixel grabbing, etc. The things are too complex for me to understand being a beginner in this field. My questions are: From where can i get started?? Is there any book available or a site which give tutorials for learning about how to actually use these techniques? Are there new techniques which can be implemented for this

How make matching X-axis in histogram with marginal boxplot? data <- rnorm(1000) nf <- layout(mat = matrix(c(1,2),2,1, byrow=TRUE), height = c(1,3)) layout.show(nf) par(mar=c(5.1, 4.1, 1.1, 2.1)) boxplot(data, horizontal=TRUE, outline=FALSE) hist(data) One solution would be to set ylim= in boxplot() to the same range as xlim= in hist() . set.seed(123) data <- rnorm(1000) nf <- layout(mat = matrix(c(1,2),2,1, byrow=TRUE), height = c(1,3)) par(mar=c(5.1, 4.1, 1.1, 2.1)) boxplot(data, horizontal=TRUE, outline=FALSE,ylim=c(-4,4)) hist(data,xlim=c(-4,4)) Using ggplot and grid package. library

I am using matplotlib.pyplot to create histograms. I'm not actually interested in the plots of these histograms, but interested in the frequencies and bins (I know I can write my own code to do this, but would prefer to use this package). I know I can do the following, import numpy as np import matplotlib.pyplot as plt x1 = np.random.normal(1.5,1.0) x2 = np.random.normal(0,1.0) freq, bins, patches = plt.hist([x1,x1],50,histtype='step') to create a histogram. All I need is freq[0] , freq[1] , and bins[0] . The problem occurs when I try and use, freq, bins, patches = plt.hist([x1,x1],50,histtype

I'm trying to plot a histogram with bar chart, and I'm having difficulties figuring out how to align the x-axis labels with the actual bins. The code below generates the following plot: as you can see, the end of each x-label is not aligned to the center of its bin. The way i'm thinking about this is: when i apply a 45-degree rotation, the label pivots around its geometrical center. I was wondering if it's possible to move the pivot up to the top of the label. (Or simply translate all the labels slightly left.) import matplotlib.pyplot as plt import numpy as np #data np.random.seed(42) data =