All-pairs shortest paths (PostgreSQL)
Floyd Warshall Algorithm is Θ(V3)
Johnson’s algorithm O(V2log V + VE) . Johnson’s algorithm uses both Dijkstra and Bellman-Ford as subroutines
Dijkstra’s Single Source shortest path algorithm: O(V*VLogV) time. So using Dijkstra’s single source shortest path seems to be a better option than Floyd Warshell, but the problem with Dijkstra’s algorithm is, it doesn’t work for negative weight edge.
sudo apt-get install postgresql-9.5-postgis-scripts
psql -d yourdbname -c "CREATE EXTENSION postgis;"
Tableau Note
- Automatic zoom in map
2. Parameter->Calculation with “Case” Condition ->convert to Dimension-> Copy one for setting color, one for Label->add filter, legend etc.
tf+Keras Note
when load model weight,
ValueError: You are trying to load a weight file containing 4 layers into a model with 0 layers.
The problem is the batchnorm. This layer wasn’t there before, so keras is complaining that the model isn’t the same.
If you really want to load weights into a different model, use model.load_weights(..., by_name=True)and ensure that the layers have the same names before and after.
Py Note
1. To get the week number
import pandas as pd
time_str = '2019-09-30T13:55:26'
pd.Timestamp(time_str[0:10]).week
2. ImportError: Cannot load backend ‘TkAgg’ which requires the ‘tk’ interactive framework, as ‘headless’ is currently running
to restart my kernel, import the following first:
import matplotlib
matplotlib.use('TKAgg')
Then,
import matplotlib.pyplot as plt
3. Invalidity of geometry when using osmnx.footprints.py
https://github.com/gboeing/osmnx/blob/5176d4a2f86fd2adaf523d3d9bd0bed9b9b1d6ec/osmnx/footprints.py
4. contextily
where is add_basemap():
contextily.plotting.add_basemap()
https://github.com/darribas/contextily/blob/master/contextily/plotting.py
5. geocube
geopandas geometry conversion
https://github.com/corteva/geocube
conda install -c conda-forge geocube
error ‘MergeAlg’
conda install -c conda-forge rasterio
6. upgrade spyder v3 to v4
conda install pyqt=5.6 (or conda install pyqt=5.9.2?)
conda install spyder=4.0.1
conda upgrade –all (do not use conda upgrade pyqt directly )
https://github.com/spyder-ide/spyder/issues/7250
when:
ImportError: cannot import name 'secure_write'
pip install –upgrade jupyter_client
NetLogo Venice Model
the model is there : http://backspaces.net/temp/NetLogoTutGIS.zip
Configuring python extension for NL
Configuring:
1. python=>Configure=>
python3=/path/to/python3
python2=/path/to/python2
1. If you use virtualenv or Conda, simply specify the path of the Python executable in the environment you wish to use:
py:setup “/path/to/myenv/bin/python”
or:
py:setup py:python ; if your code works with either Python 2 or 3
py:setup py:python3 ; for Python 3
py:setup py:python2 ; for Python 2
Set variables:
py:set “Python_Var_Name” NLogo_Var_Name
z.B.
py:set “state_dims” length inputs
py:set “hl_size” 36
Unsupervised Learning
AutoKeras
Auto-Keras is an open source software library for automated machine learning (AutoML). It is developed by DATA Lab at Texas A&M University and community contributors. The ultimate goal of AutoML is to provide easily accessible deep learning tools to domain experts with limited data science or machine learning background. Auto-Keras provides functions to automatically search for architecture and hyperparameters of deep learning models.
https://github.com/keras-team/autokeras
mnist autokeras’ version
from keras.datasets import mnist
from autokeras.image_classifier import ImageClassifier
if __name__ == '__main__':
(x_train, y_train), (x_test, y_test) = mnist.load_data()
x_train = x_train.reshape(x_train.shape + (1,))
x_test = x_test.reshape(x_test.shape + (1,))
clf = ImageClassifier(verbose=True, augment=False)
clf.fit(x_train, y_train, time_limit=12 * 60 * 60)
clf.final_fit(x_train, y_train, x_test, y_test, retrain=True)
y = clf.evaluate(x_test, y_test)
print(y * 100)
React-Native笔记
1. 搭建环境
https://reactnative.cn/docs/0.41/getting-started.html
总结：模拟器还是Genymotion好用
2. 实例学习-小明找厕所
https://github.com/liumingmusic/react-native-full-example
下载：git clone https://github.com/liumingmusic/react-native_toiletApp.git
安装：cd toilet –> npm install –> react-native run-ios(run-android)
win 10上遇到问题：
FAILURE: Build failed with an exception.
* Where:
Build file ‘D:\MU\react-native_toiletApp\toilet\android\app\build.gradle’ line: 110
* What went wrong:
A problem occurred evaluating project ‘:app’.
> Could not find property ‘MYAPP_RELEASE_STORE_PASSWORD’ on SigningConfig_Decorated{name=release, storeFile=D:\MU\react-native_toiletApp\toilet\android\app\my-release-key.keystore, storePassword=null, keyAlias=null, keyPassword=null, storeType=D:\MU\react-native_toiletApp\toilet\android\app\my-release-key.keystore}.
* Try:
Run with –stacktrace option to get the stack trace. Run with –info or –debug option to get more log output.
BUILD FAILED
Total time: 10.644 secs
Could not install the app on the device, read the error above for details.
Make sure you have an Android emulator running or a device connected and have
set up your Android development environment:
https://facebook.github.io/react-native/docs/android-setup.html
原因：gradle properties设置不正确，因此release app时出错
Could not find property ‘MYAPP_RELEASE_STORE_PASSWORD’
This is caused by the first parameter of signing configuration in build.gradle file:
storeFile file(MYAPP_RELEASE_STORE_FILE)
解决方法：
需要在../android/gradle.properties中指定参数在. 在 Windows OS正确设置如下：
MYAPP_RELEASE_STORE_FILE=KEYSTORE_NAME.keystore MYAPP_RELEASE_KEY_ALIAS=YOUR_ALIAS MYAPP_RELEASE_STORE_PASSWORD=***** MYAPP_RELEASE_KEY_PASSWORD=***** 参见：http://10minbasics.com/react-native-could-not-find-property-myapp_release_store_file/
poplarwood.wordpress.com 