Python Code Cookbook

See also:

Learning Python, the Language


Get column_nr in pandas/numpy.

if isinstance(X, pd.DataFrame):

X_is_df = True

row_nr = X.shape[0]

column_nr = X.shape[1]

if isinstance(X.columns, pd.core.index.MultiIndex):

df_columns_is_multi_index = True



Boot Partitions, Install Multi-OS

See also: easy2boot, Automatic-Unattended-Install-of-Ubuntu.

When installing Ubuntu, it will decide what kind of partition to use:

Ubuntu decicison tree for using entire disk:

? installer booted in EFI mode or BIOS mode?


: use gpt and never make biosboot


? is the disk larg......

Steps to Check Netwok Interface Card (NIC) Configurations

Check the physical NIC is connected.


Note: The NIC will be shown regardless if drivers are installed, this is a PCI feature. Ref.

Then check if it is recognized as network interfaces:

ifconfig -a

Check if it is up:




apt-get install quota


Add options usrquota,grpquota in /etc/fstab:

UUID=a5bcc8d7-asdf / ext4 errors=remount-ro,usrquota,grpquota 0 1

Set quota:

setquota -u -F vfsv0 USERNAME 4000000 5000000 0 0 /

4 000 000 ≈ 4GB.

OBS: block size is always 1 KB as unit, regardless file ......

VirtualBox Network and Skills

OBS: cloning a VM with the status of pause (not powered-off), it canNOT re-initialize the MAC address. Thus, it is necessary to disconnect the cable and poweroff to re-initialize the MAC and then boot.


Two NICs are needed BEFORE installing the system to avoid messy issues.

To let the guests......

Restful API

The insomnia client is used, (Postman is too slow, SoapUI has not been tested).