I am a university student using my university's computing cluster.
I installed Tex Live to my home directory at ~/.local/texlive/. I have a file called mplrc. The MATPLOTLIBRC environment variable is set to the mplrc file. The mplrc file contains the following lines
backend: pgf
pgf.rcfonts: false
pgf.texsystem: pdflatex
pgf.preamble: \input{mpl_settings.tex}
text.usetex: true
font.family: serif
font.size: 12
The mpl_settings.tex file is in the same directory as the mplrc file and contains the following
\usepackage{amsmath}
\usepackage[T1]{fontenc}
\usepackage{gensymb}
\usepackage{lmodern}
\usepackage{siunitx}
On the cluster I am using, I must submit a SLURM job to run the Jupyter notebook. The example code I am trying to run within the notebook is
formula = (
r'$\displaystyle '
r'N = \int_{E_\text{min}}^{E_\text{max}} '
r'\int_0^A'
r'\int_{t_\text{min}}^{t_\text{max}} '
r'\Phi_0 \left(\frac{E}{\SI{1}{\GeV}}\right)^{\!\!-γ}'
r' \, \symup{d}A \, \symup{d}t \, \symup{d}E'
r'$'
)
def power_law_spectrum(energy, normalisation, spectral_index):
return normalisation * energy**(-spectral_index)
bin_edges = np.logspace(2, 5, 15)
bin_centers = 0.5 * (bin_edges[:-1] + bin_edges[1:])
y = power_law_spectrum(bin_centers, 1e-5, 2.5)
relative_error = np.random.normal(1, 0.2, size=len(y))
y_with_err = relative_error * y
fig, ax = plt.subplots()
ax.errorbar(
np.log10(bin_centers),
y_with_err,
xerr=[
np.log10(bin_centers) - np.log10(bin_edges[:-1]),
np.log10(bin_edges[1:]) - np.log10(bin_centers)
],
yerr=0.5 * y_with_err,
linestyle='',
)
ax.text(0.1, 0.1, formula, transform=plt.gca().transAxes)
ax.set_yscale('log')
fig.tight_layout(pad=0)
plt.show()
This generates an enormous error message, but the root of it is
RuntimeError: latex was not able to process the following string:
b'lp'
However, underneath that, I see what I think is the real problem
! LaTeX Error: File `article.cls' not found.
I've set my PATH so that it finds the right latex command, but what else needs to be set in order to find the article.cls file? It seems like it's something particular to the Python notebook. When running kpsewhich article.cls in a terminal within the Jupyterlab interface, the file gets found. But trying ! kpsewhich article.cls or subprocess.run(['kpsewhich', 'article.cls']) within the Python notebook does not find the file.
I figured it out. I forgot I had run a section of code which set
TEXINPUTS=/path/to/some/directory
Looks like I missed a : in my TEXINPUTS, so TeX was only looking in /path/to/some/directory
The solution was to have
TEXINPUTS=/path/to/some/directory:
That way it looked in my current directory, but also continued looking elsewhere.
I'm trying to split a huge tiff file into tiles using gdal on Colab.
My google drive is mounted and I can read and write from / into it.
The code is taken from this answer:
com_string = "gdal_translate -of GTIFF -srcwin" + ...
os.system(com_string)
The cell completes but no new files show up on the drive.
Any ideas or another way to achieve the splitting of the file?
This answer gives a suggestion:
You would need to come up with the pixel/line locations or corner coordinates and then loop over the values with gdal_translate.
import os, sys
from osgeo import gdal
dset = gdal.Open(sys.argv[1])
width = dset.RasterXSize
height = dset.RasterYSize
print width, 'x', height
tilesize = 5000
for i in range(0, width, tilesize):
for j in range(0, height, tilesize):
w = min(i+tilesize, width) - i
h = min(j+tilesize, height) - j
gdaltranString = "gdal_translate -of GTIFF -srcwin "+str(i)+", "+str(j)+", "+str(w)+", " \
+str(h)+" " + sys.argv[1] + " " + sys.argv[2] + "_"+str(i)+"_"+str(j)+".tif"
os.system(gdaltranString)
This, of course, relies on your gdal installation working properly. If the above doesn't work (you get no files still) try first running it in a location that isn't a mounted Google Drive. If that works, you know the problem is with your mounting. If not, next I would check to make sure you are getting the input image you are expecting with something like plt.imshow(your_source_image). If you see the image, then move on. If not, your source image is either missing or the path is wrong.
If it still doesn't work, I'd suspect it is a problem with your gdal installation. In that case I would first try a very simple function and make sure it gives the result you expect. You can also try running something else on Collab and make sure that works.
I am trying to do a basic colour conversion in python however I can't seem to get past the below error. I have re-installed python, opencv and tried on both python 3.4.3 (latest) and python 2.7 (which is on my Mac).
I installed opencv using python's package manager opencv-python.
Here is the code that fails:
frame = cv2.imread('frames/frame%d.tiff' % count)
frame_HSV= cv2.cvtColor(frame,cv2.COLOR_RGB2HSV)
This is the error message:
cv2.error: OpenCV(3.4.3) /Users/travis/build/skvark/opencv-python/opencv/modules/imgproc/src/color.cpp:181: error: (-215:Assertion failed) !_src.empty() in function 'cvtColor'
This error happened because the image didn't load properly. So you have a problem with the previous line cv2.imread. My suggestion is :
check if the image exists in the path you give
check if the count variable has a valid number
If anyone is experiencing this same problem when reading a frame from a webcam:
Verify if your webcam is being used on another task and close it. This wil solve the problem.
I spent some time with this error when I realized my camera was online in a google hangouts group. Also, Make sure your webcam drivers are up to date
I kept getting this error too:
Traceback (most recent call last):
File "face_detector.py", line 6, in <module>
gray_img=cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
cv2.error: OpenCV(4.1.0) C:\projects\opencv-python\opencv\modules\imgproc\src\color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function 'cv::cvtColor
My cv2.cvtColor(...) was working fine with \photo.jpg but not with \news.jpg. For me, I finally realized that when working on Windows with python, those escape characters will get you every time!! So my "bad" photo was being escaped because of the file name beginning with "n". Python took the \n as an escape character and OpenCV couldn't find the file!
Solution:
Preface file names in Windows python with r"...\...\" as in
cv2.imread(r".\images\news.jpg")
If the path is correct and the name of the image is OK, but you are still getting the error
use:
from skimage import io
img = io.imread(file_path)
instead of:
cv2.imread(file_path)
The function imread loads an image from the specified file and returns
it. If the image cannot be read (because of missing file, improper permissions, unsupported or invalid format), the function returns an empty matrix ( Mat::data==NULL ).
check if the image exists in the path and verify the image extension (.jpg or .png)
Check whether its the jpg, png, bmp file that you are providing and write the extension accordingly.
Another thing which might be causing this is a 'weird' symbol in your file and directory names. All umlaut (äöå) and other (éóâ etc) characters should be removed from the file and folder names. I've had this same issue sometimes because of these characters.
Most probably there is an error in loading the image, try checking directory again.
Print the image to confirm if it actually loaded or not
In my case, the image was incorrectly named. Check if the image exists and try
import numpy as np
import cv2
img = cv2.imread('image.png', 0)
cv2.imshow('image', img)
I've been in same situation as well, and My case was because of the Korean letter in the path...
After I remove Korean letters from the folder name, it works.
OR put
[#-*- coding:utf-8 -*-]
(except [ ] at the edge)
or something like that in the first line to make python understand Korean or your language or etc.
then it will work even if there is some Koreans in the path in my case.
So the things is, it seems like there is something about path or the letter.
People who answered are saying similar things. Hope you guys solve it!
I had the same problem and it turned out that my image names included special characters (e.g. château.jpg), which could not bet handled by cv2.imread. My solution was to make a temporary copy of the file, renaming it e.g. temp.jpg, which could be loaded by cv2.imread without any problems.
Note: I did not check the performance of shutil.copy2 vice versa other options. So probably there is a better/faster solution to make a temporary copy.
import shutil, sys, os, dlib, glob, cv2
for f in glob.glob(os.path.join(myfolder_path, "*.jpg")):
shutil.copy2(f, myfolder_path + 'temp.jpg')
img = cv2.imread(myfolder_path + 'temp.jpg')
img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
os.remove(myfolder_path + 'temp.jpg')
If there are only few files with special characters, renaming can also be done as an exeption, e.g.
for f in glob.glob(os.path.join(myfolder_path, "*.jpg")):
try:
img = cv2.imread(f)
img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
except:
shutil.copy2(f, myfolder_path + 'temp.jpg')
img = cv2.imread(myfolder_path + 'temp.jpg')
img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
os.remove(myfolder_path + 'temp.jpg')
In my case it was a permission issue. I had to:
chmod a+wrx the image,
then it worked.
must please see guys that the error is in the cv2.imread() .Give the right path of the image. and firstly, see if your system loads the image or not. this can be checked first by simple load of image using cv2.imread().
after that ,see this code for the face detection
import numpy as np
import cv2
cascPath = "/Users/mayurgupta/opt/anaconda3/lib/python3.7/site- packages/cv2/data/haarcascade_frontalface_default.xml"
eyePath = "/Users/mayurgupta/opt/anaconda3/lib/python3.7/site-packages/cv2/data/haarcascade_eye.xml"
smilePath = "/Users/mayurgupta/opt/anaconda3/lib/python3.7/site-packages/cv2/data/haarcascade_smile.xml"
face_cascade = cv2.CascadeClassifier(cascPath)
eye_cascade = cv2.CascadeClassifier(eyePath)
smile_cascade = cv2.CascadeClassifier(smilePath)
img = cv2.imread('WhatsApp Image 2020-04-04 at 8.43.18 PM.jpeg')
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
faces = face_cascade.detectMultiScale(gray, 1.3, 5)
for (x,y,w,h) in faces:
img = cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)
roi_gray = gray[y:y+h, x:x+w]
roi_color = img[y:y+h, x:x+w]
eyes = eye_cascade.detectMultiScale(roi_gray)
for (ex,ey,ew,eh) in eyes:
cv2.rectangle(roi_color,(ex,ey),(ex+ew,ey+eh),(0,255,0),2)
cv2.imshow('img',img)
cv2.waitKey(0)
cv2.destroyAllWindows()
Here, cascPath ,eyePath ,smilePath should have the right actual path that's picked up from lib/python3.7/site-packages/cv2/data here this path should be to picked up the haarcascade files
Your code can't find the figure or the name of your figure named the by error message.
Solution:
import cv2
import numpy as np
import matplotlib.pyplot as plt
img=cv2.imread('哈哈.jpg')#solution:img=cv2.imread('haha.jpg')
print(img)
If anyone is experiencing this same problem when reading a frame from a webcam [with code similar to "frame = cv2.VideoCapture(0)"] and work in Jupyter Notebook, you may try:
ensure previously tried code is not running already and restart Jupyter Notebook kernel
SEPARATE code "frame = cv2.VideoCapture(0)" in separate cell on place where it is [previous code put in cell above, code under put to cell down]
then run all the code above cell where is "frame = cv2.VideoCapture(0)"
then try run next cell with its only code "frame = cv2.VideoCapture(0)" - AND - till you will continue in executing other cells - ENSURE - that ASTERIX on the left side of this particular cell DISAPEAR and command order number appear instead - only then continue
now you can try execute the rest of your code as your camera input should not be empty anymore :-)
After end, ensure you close all your program and restart kernel to prepare it for another run
As #shaked litbak , this error arised with my initial use with the ASCII-generator , as i naively thought i just had to add to the ./data directory , with its load automatically .
I had to append the --input option with the desired file path .
I checked my image file path and it was correct. I made sure there was no corrupt images.The problem was with my mac. It sometimes have a hidden file called .DS_Store which was saved together with the image file path. Therefore cv2 was having a problem with that file.So I solved the problem by deleting .DS_Store
I also encountered this type of error:
error: OpenCV(4.1.2) /io/opencv/modules/imgproc/src/color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function 'cvtColor'
The solution was to load the image properly. Since the file mentioned was wrong, images were not loaded and hence it threw this error. You can check the path of the image or if uploading an image through colab or drive, make sure that the image is present in the drive.
I encounter the problem when I try to load the image from non-ASCII path.
If I simply use imread to load the image, I am only able to get None.
Here is my solution:
import cv2
import numpy as np
path = r'D:\map\上海地图\abc.png'
image = cv2.imdecode(np.fromfile(path, dtype=np.uint8), cv2.IMREAD_UNCHANGED)
Similar thing will happen when I save the image in a non-ASCII path. It will not be successfully saved without any warnings. And here is what I did.
import cv2
import numpy as np
path = r'D:\map\上海地图\abc.png'
cv2.imencode('.png', image)[1].tofile(path)
path = os.path.join(raw_folder, folder, file)
print('[DEBUG] path:', path)
img = cv2.imread(path) #read path Image
if img is None: # check if the image exists in the path you give
print('Wrong path:', path)
else: # It completes the steps
img = cv2.resize(img, dsize=(128,128))
pixels.append(img)
The solution os to ad './' before the name of image before reading it...
Just Try Degrading the OpenCV
in python Shell (in cmd)
>>> import cv2
>>> cv2.__version__
after Checking in cmd
pip uninstall opencv-python
after uninstalling the version of opencv install
pip install opencv-python==3.4.8.29
I am using code provided by tensorflow to load data: https://www.tensorflow.org/beta/tutorials/load_data/text
When I put in my own photos, it sends to a different directory. The code wants attributions from my LICENSE.txt, but I am not sure what the purpose of this code segment is.
I made my own LICENSE.txt file by just making a text file with each line being a title of an image. When I do this, it makes attributions a dictionary in which each key is the filename and each corresponding value is ''. When I run another method, I get a key error for every file.
import os
attributions = (data_root/"LICENSE.txt").open(encoding='utf- 8').readlines()
attributions = [line.split('\n') for line in attributions]
print(attributions)
attributions = dict(attributions)
import IPython.display as display
def caption_image(image_path):
image_rel = pathlib.Path(image_path).relative_to(data_root)
return "Image (CC BY 2.0) " + ' -'.join(attributions[str(image_rel)].split(' - ')[:-1])
for n in range(3):
image_path = random.choice(all_image_paths)
display.display(display.Image(image_path))
print(caption_image(image_path))
print()
I do not really know what to expect when I run the for loop in jupyter notebook, but it gives me a key error, the key being the file name.
I wrote that tutorial. The license lookup is only there so we can directly arttribute the individual photographers when we publish it. If you're working with your own images you don't need that part of the code at all.
All it's really doing is choosing a random image and displaying it. You can simplify it to:
import os
import IPython.display as display
for n in range(3):
image_path = random.choice(all_image_paths)
display.display(display.Image(image_path))