In various cases whenever I use latex in matplotlib, I am getting a very pixely appearance when rendering the figure to an image. When I view the figure in interactive mode it looks fine. For example, I'm setting the yaxis label with:
'Emissions Flux '+r'($\mathregular{(\mu g/m^2 s)}$'
I'm also setting the twin y axis to a log scale and the eponents are presumably latex as well. Non latex text is crisp.
I as far I understand the problem your images are too pixelated. Often this is the result of saving an image using a bitmap format. To receive better images one should export them to vector-graphs, like for example pdf.
To export images as vector-graphs your save statement should be something like:
myfig.savefig('myfig.pdf', format='pdf')
A clear explanation about bitmaps and vector graphs: http://www.prepressure.com,
an important source of information concerning matlibplot: http://matplotlib.org
Related
When I use Matplotlib's plt.show() I get a nice Plot which can can be zoomed to very high precision(practically infinite). But when I save it as a image it loses all this information gives information depending on resolution.
Is there any way I can save the plot with the entire information? i.e Like those interactive plots which can rescaled at any time?
P.S- I know I can set dpi to get high quality images. This is not what I want. I want image similar to Plot which python shows when I run the program. What format is that? Or is it just very high resolution image?
Note- I am plotting .csv files which includes data varying from 10^(-10) to 100's. Thus when I save the plot as .png file I lose all the information/kinks of graph at verŠ½ small scales and only retain features from 1-100.
Maybe the interactive graphic library bokeh is an option for you. See here. It's API is just little different from what you know from matplotlib.
Bokeh creates plots as html files that you can view in your browser. For each graphic you can select wheel zoom to zoom interactively into your graphic. You can change interactively the range that you want to be plotted. Therefore you don't loose information in your graphic.
I have a problem with Matplotlib. I usually make big plots with many data points and then, after zooming or setting limits, I save in pdf only a specific subset of the original plot. The problem comes when I open this file: matplotlib saves all the data into the pdf making not visible the one outside of the range. This makes almost impossible to open afterwards those plots or to import them into latex.
Any idea of how I could solve this problem is really welcome.
Thanks a lot
If you don't have a requirement to use PDF figures, you can save the matplotlib figures as .png; this format just contains the data on the screen, e.g. I tried saving a large scatter plot as PDF, its size was 198M; as png it came out as 270K; plus I've never had any problems using png inside latex.
I have not tested that this will work, but it might be worth rasterizing some of the artists:
fig, ax = plt.subplots()
ax.imshow(..., rasterized=True)
fig.savefig('test.png', dpi=600)
which will rasterize the artist when saving to vector formats. If you use a high enough dpi this should give you reasonable quality.
I'm preparing some plots for a scientific paper, which need to be wide and short in order to fit into the page limit. However, when I save them as pdf, the x axis labels are missing, because (I think) they're outside the bounding box.
Putting the following into an iPython notebook reproduces the problem.
%pylab inline
pylab.rcParams['figure.figsize'] = (8.0, 2.0)
plot([1,5,2,4,6,2,1])
xlabel("$x$")
ylabel("$y$")
savefig("test.pdf")
The resulting pdf file looks like this:
How can I change the bounding box of the pdf file? Ideally I'd like a solution that "does it properly", i.e. automatically adjusts the size so that everything fits neatly, including getting rid of that unnecessary space to the left and right - but I'm in a hurry, so I'll settle for any way to change the bounding box, and I'll guess numbers until it looks right if I have to.
After a spot of Googling, I found an answer: you can give bbox_inches='tight' to the savefig command and it will automatically adjust the bounding box to the size of the contents:
%pylab inline
pylab.rcParams['figure.figsize'] = (8.0, 2.0)
plot([1,5,2,4,6,2,1])
xlabel("$x$")
ylabel("$y$")
savefig("test.pdf",bbox_inches='tight')
Those are some tight inches, I guess.
Note that this is slightly different from Ffisegydd's answer, since it adjusts the bounding box to the plot, rather than changing the plot to fit the bounding box. (But both are fine for my purposes.)
You can use plt.tight_layout() to have matplotlib adjust the layout of your plot. tight_layout() will automatically adjust the dimensions, and can also be used when you have (for example) overlapping labels/ticks/etc.
%pylab inline
pylab.rcParams['figure.figsize'] = (8.0, 2.0)
plot([1,5,2,4,6,2,1])
xlabel("$x$")
ylabel("$y$")
tight_layout()
savefig("test.pdf")
Here is a .png of the output (can't upload pdfs to SO but I've checked it and it works the same way for a pdf).
If you are preparing the plot for a scientific paper, I suggest to do the 'clipping' by yourself,
using
plt.subplots_adjust(left,right,bottom,top,..)
after the creation of the figure and before saving it. If you are running from an ipython console you can also call subplots_adjust after the generation of the figure, and tune the margins by trial and error. Some backends (I think at least the Qt backend) also expose a GUI for this feature.
Doing this by hand takes time, but most times provides a more precise result, especially with Latex rendering in my experience.
This is the only option whenever you have to stack vertically or horizontally two figures (with a package like subfigure for example), as tight_layout will not guarantee the same margins in the two figures, and the axis will result misaligned in the paper.
This is a nice link on using matplotlib for publications, covering for example how to set the figure width to match the journal column width.
I am creating plots on which I need to place small bitmaps at a given
location with a given size (ships, navigational markers, and some
results of my analysis). I was unable to force imshow() dropping my
bitmap in the right place, and the examples with add_patch() do not
show anything like I need. Can it be done what I need? If so, how?
Thank you
How can I save Python plots at very high quality?
That is, when I keep zooming in on the object saved in a PDF file, why isn't there any blurring?
Also, what would be the best mode to save it in?
png, eps? Or some other? I can't do pdf, because there is a hidden number that happens that mess with Latexmk compilation.
If you are using Matplotlib and are trying to get good figures in a LaTeX document, save as an EPS. Specifically, try something like this after running the commands to plot the image:
plt.savefig('destination_path.eps', format='eps')
I have found that EPS files work best and the dpi parameter is what really makes them look good in a document.
To specify the orientation of the figure before saving, simply call the following before the plt.savefig call, but after creating the plot (assuming you have plotted using an axes with the name ax):
ax.view_init(elev=elevation_angle, azim=azimuthal_angle)
Where elevation_angle is a number (in degrees) specifying the polar angle (down from vertical z axis) and the azimuthal_angle specifies the azimuthal angle (around the z axis).
I find that it is easiest to determine these values by first plotting the image and then rotating it and watching the current values of the angles appear towards the bottom of the window just below the actual plot. Keep in mind that the x, y, z, positions appear by default, but they are replaced with the two angles when you start to click+drag+rotate the image.
Just to add my results, also using Matplotlib.
.eps made all my text bold and removed transparency. .svg gave me high-resolution pictures that actually looked like my graph.
import matplotlib.pyplot as plt
fig, ax = plt.subplots()
# Do the plot code
fig.savefig('myimage.svg', format='svg', dpi=1200)
I used 1200 dpi because a lot of scientific journals require images in 1200 / 600 / 300 dpi, depending on what the image is of. Convert to desired dpi and format in GIMP or Inkscape.
Obviously the dpi doesn't matter since .svg are vector graphics and have "infinite resolution".
You can save to a figure that is 1920x1080 (or 1080p) using:
fig = plt.figure(figsize=(19.20,10.80))
You can also go much higher or lower. The above solutions work well for printing, but these days you want the created image to go into a PNG/JPG or appear in a wide screen format.
Okay, I found spencerlyon2's answer working. However, in case anybody would find himself/herself not knowing what to do with that one line, I had to do it this way:
beingsaved = plt.figure()
# Some scatter plots
plt.scatter(X_1_x, X_1_y)
plt.scatter(X_2_x, X_2_y)
beingsaved.savefig('destination_path.eps', format='eps', dpi=1000)
In case you are working with seaborn plots, instead of Matplotlib, you can save a .png image like this:
Let's suppose you have a matrix object (either Pandas or NumPy), and you want to take a heatmap:
import seaborn as sb
image = sb.heatmap(matrix) # This gets you the heatmap
image.figure.savefig("C:/Your/Path/ ... /your_image.png") # This saves it
This code is compatible with the latest version of Seaborn. Other code around Stack Overflow worked only for previous versions.
Another way I like is this. I set the size of the next image as follows:
plt.subplots(figsize=(15,15))
And then later I plot the output in the console, from which I can copy-paste it where I want. (Since Seaborn is built on top of Matplotlib, there will not be any problem.)