This is a collection of various keyboard shortcuts that can make your life easier when using the atom editor with the hydrogen connection to a jupyter kernel.

These have been tested on my machine with Atom 1.32.1 and Ubuntu. If there are differences across operating systems, or they require specific packages, please point it out.

General Atom commands

Shift + Ctrl + p

open the command shell. From here one can access all the more advanced functions. it will also show the current keyboard shortcut for the chosen command, if present. can do partial search, so it will find commands based on keyword in the middle of the commands themselves (for example, the Hydrogen: Add Watch can be found just with watch)
Ctrl + , comma

open the Settings tab
Ctrl + / slash (on an italian keyboad is Ctrl + shift + 7 )

toggle comment of the code
Ctrl + shift + m

toggle the preview for markdown files. (requires the markdown-preview extension)
Alt + shift + T

toggle the todo list as a side panel (requires the todo-show extension)

bookmark management (`F2`)

bookmarks allow you to quickly explore your code and go back and forth between different sections

Ctrl + shift + F2

add or remove a bookmark to a line
F2 and Shift + F2

move to the next (or previous) bookmark in the current file
Ctrl + F2

list the current bookmarks and allow to jump to the chosen one. Can see the bookmarks in all the files you have opened.

Find and Replace (with multiple selections)

it will select multiple copies of the same string. It is great for a mass rename of a variable or a function in a file.

if you move the cursor after the selection, you will get multiple cursors. This is very useful to change the arguments for all the calls of a given function.

Ctrl + d

select the current object, if selected find the next
Alt + F3

finds and select all
Ctrl + k and then Ctrl + d

skip the selection to the next one
Ctrl + u

undo the last selection
Shift + Alt + ↑ up arrow and Shift + Alt + ↓ down arrow

create multiple cursors above and below the current one. this is very useful to modify several consecutive lines

selection management

Alt + ↑ up arrow and Alt + ↓ down arrow

select (or deselect) the higher level of syntax block from the current selection. for example, from the cursor it will select the variable name it is placed on, then the function call list of arguments, then the whole function, and so on
Ctrl + Alt + , comma

select all the content inside the current function call.
Ctrl + r

finds all the symbols defined in the current files (functions, variables, etc...)
Ctrl + ↑ up arrow and Ctrl + ↓ down arrow

move the current line above or below
Shift + Alt + ↑ up arrow and Shift + Alt + ↓ down arrow

put multiple cursors above or below the current one. one can return to a single cursor pressing Esc
Ctrl + g

goes to a specific line
Ctrl + l

select the whole line the cursor is currently on
Ctrl + left arrow or right arrow

skip to the previous or next word. using Alt instead of Ctrl allows a more fine-grained control. combined with Shift can be used to select text.
Ctrl + Del or Backspace

delete to the end (or the beginning) of the current word.
Shift + Home or End

Select the text to the start of the line or the the end of it
Ctrl + Home or End

go the the beginning or the end of the file

Execution of code on hydrogen

Shift + Enter

execute a selection or the current line in hydrogen, go to the next one
Ctrl + Enter

execute a selection or the current line in hydrogen, stays on the current one
Shift + Alt + Enter

Execute the current block and go to the next one (blocks are delimited by # %%)
Ctrl + Alt + Enter

Execute the current block and remains in it (blocks are delimited by # %%)
Alt + i

open the inline help of hydrogen with the help of the function or object that the cursor is corrently residing on

Watches and Explorative work

from the command shell: search for Hydrogen: Add Watch

create a new watch. Watches allow for small snippets of code to be execute whenever you launch a new command. They can be useful to check the results of a plot when you modify the way data are processed.
from the command shell: search for Hydrogen Python: toggle variable explorer

show as a side tab a simple variable explorer similar to those of spyder and matlab (but less powerful)
from the command shell: search for Hydrogen: toggle output area

show a new area on the side that display the results of the executed commands instead of showing them inline. this is very useful to select text from the output, as the inline version does not allow text selection.

for this kind of explorative work, there are few useful snippets to be used

library pdir2

is a drop-in replacement for the default dir function, with some more goodies. import it with import pdir as dir and then put a watch with
```
  dir().public
```
to have a list of all the functions and modules and a short help
IPython JSON display

useful to display dictionaries and lists of simple objects in an interactive way. import it with from IPython.display import JSON and then use it with
```
  data = [1, 2, {'a':1}]
  JSON(data, expanded=True)
```
pandas styles

these are useful when doing data exploration. instead of just displaing the basic dataframe, with this one can have a rich display. one can access a dataframe style with .style, and then create a rich display using pre-defined functions or extending them as you need
```
  d = pd.DataFrame(plt.randn(5, 3))
  d[0] = plt.nan
  d.style
  d.style.highlight_null()
  d.style.highlight_null().highlight_max()
  d.style.highlight_max(color='darkorange', axis=1)
  d.style.background_gradient()
```
you can have the whole list with dir(d.style).public.methods
pandas_profiling

generates reports on a dataframe, including statistics, correlations, etc... Can be installed with conda install pandas_profiling.
```
  import pandas_profiling
  df = pd.DataFrame(plt.randn(500, 3))
  pandas_profiling.ProfileReport(df)
```
a similar library is pivottablejs, but only works in jupyter notebooks, so I haven't tested it.
search stackoverflow for code snippets

requires the package ask-stack. typing ask stack in the command prompt will open a search box that will then return a series of replies from stackoverflow that can be explored directly in the sidebar.
special character variables

ipython allow to replace special letters name with the proper representation with a ⇥ Tab. For example, it can replace \alpha with α. Atom is able to do it by itself, but I don't remember from which version. This is useful to write expressive formulas, but should be used sparingly as it makes it hard to edit for someone that does not have a similar tool. it is possible to insert letter modifiers as well, such as hat, dot and so on. to make it acceptable to python, first should be the letter, than the modifier, such as a\hat for â. This can make the code difficult to read with smaller fonts, so beware. Only the unicode letters can be used, so you can't have a cat face 😺 for a variable, but you can have it as dictionary key if you want the world to burn.

display online math

  from IPython.display import Math
  formula = r'i\hbar \frac{dA}{dt}~=~[A(t),H(t)]+i\hbar \frac{\partial A}{\partial t}.'
  Math(formula)

code block descriptions

dividing the script in code blocks is useful to keep the code nicely sorted. It is even better to put a docstring for each block to make clear what the block is about. one simple way is to put a multiline string at the beginning of it. To avoid repeating the docstring when you execute the script line by line, just put a semicolon after it.
```
  """
  docstring
  """;
```
one more fancy way to do it is to import the markdown display of ipython and wrapping the docstring with it. it will display it, and if you fold the code of the markdown, you just get the nice visualization without the raw string.
```
  from IPython.display import Markdown

  Markdown("""# test

  * riga 1
  * riga 2
  """)
```
artificial code blocks

sometimes it is useful to collect a bunch of code in a block to be executed all together, or disables all together. One way of doing it that works reasonably well without relying on the code block convetion is to use an if statement with a short descriptive string.
```
  if "print something to screen":
      a = 3
      print(a)
```
if you want to skip the whole block all together you can just interpose a not between the if and the description string.
```
  if not "execute my awesome code that is useless now":
      pass
```

useful extensions for ipython

ipython-sql to exectute SQL calls inside your script

load it with

  %load_ext sql

then you can run SQL commands as a block

  %%sql sqlite://
  CREATE TABLE writer (first_name, last_name, year_of_death);
  INSERT INTO writer VALUES ('William', 'Shakespeare', 1616);
  INSERT INTO writer VALUES ('Bertold', 'Brecht', 1956);

or as a single instruction

  a = %sql select * from writer
  a.DataFrame() # to get it as a pandas data frame

it can also do dinamic binding to existing variables:

  state='FINISHED'
  %sql SELECT :state as "bind_variable"

cython (included in the cython package)

allow to magically compile and import cython functions for extra performance
```
  %load_ext cython
```
then declare and execute a cython block
```
  %%cython
  cpdef myfunction(int a, int b):
      return a+b
```
if it runs successfully, it will import the function in the current namespace
```
  >>> myfunction(4, 5)
  9
```

configurations and packages

file-icons for pretty icons on the file browser to help navigating
highlight-selected show all the locations of the string that is highlighted
minimap and to have a side bar with a bird-eye view of the source code.

it does have several plugins that can be installed (and activated and deactivated at will from the config icon that appears if you hover the mouse over the minimap)
- minimap-bookmarks and minimap-highlight-selected
  
  display in the minimap the selected text and the bookmarks
- minimap-titles
  
  use the command Ctrl + shift + ⌫ Del to replace the selected text with ASCII graphics. this allow to generate titles readable in the minimap. if you apply to the word text, you obtain:
```
  ████████ ███████ ██   ██ ████████
     ██    ██       ██ ██     ██
     ██    █████     ███      ██
     ██    ██       ██ ██     ██
     ██    ███████ ██   ██    ██
```
- minimap-codeglance
  
  codeglance helps preview the code from the minimap and is very useful, but the default graphics can be improved. I would suggest the following style. in the file ~/.atom/styles.less, adding:
```
  minimap-codeglance {
    box-shadow: 0 0 40px rgba(127, 127, 127, 1);
  }
```
todo-show to have a side bar with the TODOs and NOTEs for the current code
teletype to collaboatively write code
simple-drag-drop-text to move around selected text with the mouse
platformio-ide-terminal include a simple terminal in the shell. might need to set source ~/.bashrc in the config to see the path properly
color-picker use Ctrl + Alt + C to open up a color explorer and generate the string with the appropriate color. Very useful when plotting stuff.
tablr allows to visualize and edit csv-like files in the editor

the repository linked in atom is not working anymore, but a working fork can be installed using:
```
  apm install https://github.com/mfripp/atom-tablr.git
```
project-manager allows to switch easily between different projects. it relies completely on the command prompt.
NOT WORKING (in hydrogen-python set extend executable code)

this makes sure that when you select a block to run such a an if statement, it runs the corresponding else as well
NOT WORKING (data-explorer)

this should allow interactive plotting of a dataframe

External articles about Atom and shortcuts

automate repetitive tasks with composed commands
Atom manual
https://github.com/nwinkler/atom-keyboard-shortcuts
https://sweetme.at/2014/03/10/atom-editor-cheat-sheet/
https://github.com/mehcode/awesome-atom

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General Atom commands

bookmark management (`F2`)

Find and Replace (with multiple selections)

selection management

Execution of code on hydrogen

Watches and Explorative work

useful extensions for ipython

configurations and packages

External articles about Atom and shortcuts

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General Atom commands

bookmark management (F2)

Find and Replace (with multiple selections)

selection management

Execution of code on hydrogen

Watches and Explorative work

useful extensions for ipython

configurations and packages

External articles about Atom and shortcuts

bookmark management (`F2`)