Learning Python, so here is jotted-down notes that might be useful, part 6.
LOG 6
* 1 – os module
- os means operating system
Each system, like Linux or Window, uses different directory syntax, like backslash (“\”) and forward slash (“/”) - Example:
root = …….. (some location)
txt_doc = …..(location) / filename.txt - os.mkdir(‘{0}/{1}’.format(root, ‘something’)) => create directory named ‘something’ at folder root
os.makedirs(‘{0}/{1}/{2}’.format(root, ‘level2’, ‘level3’)) => recursively create folders
os.rename(‘{0}/{1}/{2}’.format(root, ‘level2’, ‘level3’), ‘{0}/{1}/{2}’.format(root, ‘level2’, ‘whatever’)) => give full path for old and new names - os.access(txt_doc, os.W_OK) #use to check on directories and files for existence and ability to read/write
4 modes:
F_OK: check existence and access
R_OK: readable?
W_OK: write ok?
X_OK: executable?os.path.join => take a existing path, join another directory to the end of that - os.sep => giving the default separator of the operating system
os.sep.join(root.split(‘/’)) => split ‘root’ string separated by ‘/’ into list, then joining different componoents of the list by the separator - os.path => module designed to work with paths
os.path.split(root) => split the path and the current working dir
os.path.splitext(txt_doc) => split the path to file and its extention
os.path.splitdrive(txt_doc) => split the drive and the path
os.path.isdir(root) => check if it’s a file or directory
os.path.dirname(txt_doc) => return the directory path to the current file - open(path, ‘access mode’) function
myfile = open(txt_doc, ‘r+’)
myfile.write(‘Hahahahahahahahaha’)
myfile.close()
python will open it in the background, create a reference in memory, but we have to close it afterward for things you write in to register
access modes:
r: read
r+: read and write, reads first then write
w: write
w+: write and read, blank slate & overwrite entirely
a: append
a+: append and read
* 2 – json module
- jsoon: JavaScript Object Notation
- How json file store data
json files help store data externally from project file, help storing a hierachy of dictionary and lists.
Notice the hierachy: dictionary – list – dictionary
a dictionary with ‘humans’ keyword, value is a list of different humans, within each human is a dictionary of different attributes. - Example:
from pprint import pprint
mydata = {
‘humans’: [
{
‘Name’: ‘Tony’,
‘Age’: 22,
‘EyeColor’: ‘Brown’
},
{
‘Name’: ‘Alexis’,
‘Age’: 27,
‘EyeColor’: ‘Black’
}
]
}
mike = {
‘Name’: ‘Mike’,
‘Age’: 30,
‘EyeColor’: ‘Blue’
}
mydata[‘humans’].append(mike) => add ‘mike’ to the human list
pprint(mydata)
- Write data out to json file
path = ‘D:/01_PROJECTS/houdini/config/foo.json’
with json files, if the file does not exist, python will create it for us
#basic dumping to json
file = open(path, ‘w’)
json.dump(mydata, file)
file.close()
#dump data to json using with
with open(path, ‘w’) as file:
json.dump(mydata, file, sort_keys=True, indent=4) => sort keys and set indent for json file, 4 is commonly used
#load data from json
with open(path, ‘r’) as file:
data = json.load(file)
print data[‘humans’][0][‘Name’] => Tony
=> using a with block open and automatically closes the file for us - More functions:
js = json.dumps(mydata) => dumps is dump string, we don’t feed a file to store in, it’s just returning a string that’s been formatted in json and store in our variable in our scene
dt = json.loads(js) => loads is load string, it read in the json formatted string from a variable in our scene, and convert to python format so we can work with it
End of week 6.
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