Add Preview Functionalities
It is a very usual case when you want to preview something before actually running a function.
- Suppose in your GUI you implemented a function that can load a csv file and summarize its contents, you may want to open the csv file and see if you chose the correct file.
- Suppose you want to process a dataset in-place, you may want to add a "preview" checkbox so that you can search for the proper parameters (imagine Gaussian filter function in other softwares).
The preview functionality is, however, unexpectedly hard to be implemented in magicgui
or magic-class
.
- If they are implemented in separate buttons, say in button "summarize csv" and "preview csv", users have to synchronize all the input arguments between these two widgets.
- If they are implemented in a same widget, you have to add an additional button in the
bottom of the
FunctionGui
. This is not simple and hard to maintain. - In the case of 2, you'll have to properly connect signals such as "turn on preview", "turn off preview" and "restore the original state", which is not an easy task.
In magic-class
, impl_preview
decorator is very useful for this purpose. You can
define a preview function and directly integrate it into another function easily.
Preview a File
@impl_preview(f)
def _f_prev(self, xxx):
...
will define a previewer _f_prev
for function f
. Arguments of _f_prev
must be
composed of those in f
. The _f_prev
can be called from the FunctionGui
created by
f
, as a preview button above the call button.
from pathlib import Path
import pandas as pd
from magicgui.widgets import Table # for preview
from magicclass import magicclass, impl_preview
@magicclass
class A:
def summarize_csv(self, path: Path):
df = pd.read_csv(path)
print(df.agg([np.mean, np.std])) # print summary
@impl_preview(summarize_csv)
def _preview_csv(self, path):
df = pd.read_csv(path)
Table(value=df).show() # open table widget as the preview
Previewer don't have to accept all the arguments. Suppose you defined a function
calc_something
that calculate something using a data frame and a input parameter like
calc_something(df, param)
, the param
in not needed for preview.
@magicclass
class A:
def calc_csv(self, path: Path, param: float):
df = pd.read_csv(path)
result = calc_something(df, param)
print(result)
@impl_preview(calc_csv)
def _preview_csv(self, path): # "param" is not needed here
df = pd.read_csv(path)
Table(value=df).show()
You can mark the same function as a previewer for multiple functions.
You can also set the text of preview button using text=...
argument.
@magicclass
class A:
def summarize_csv(self, path: Path):
df = pd.read_csv(path)
print(df.agg([np.mean, np.std]))
def calc_csv(self, path: Path, param: float):
df = pd.read_csv(path)
result = calc_something(df, param)
print(result)
def plot_csv(self, path: Path):
df = pd.read_csv(path)
df.plot()
@impl_preview(summarize_csv)
@impl_preview(calc_csv)
@impl_preview(plot_csv, text="preview CSV")
def _preview_csv(self, path): # "param" is not needed here
df = pd.read_csv(path)
Table(value=df).show()
Prerun a Function
This is essentially same as 1, except that the preview function will update some parts of the GUI. Following example shows an incomplete implementation of a previewable Gaussian filtering.
from magicclass import magicclass, impl_preview, vfield
from magicgui.widgets import Image
from scipy import ndimage as ndi
@magicclass
class A:
img = vfield(Image)
def __post_init__(self):
# sample image
self.img = np.random.random((100, 100))
self["img"].min_width = 100
self["img"].min_height = 100
def gaussian_filter(self, sigma: float = 1.0):
"""Run Gaussian filter inplace"""
self.img = ndi.gaussian_filter(self.img, sigma)
@impl_preview(gaussian_filter)
def _prerun(self, sigma):
self.gaussian_filter(sigma)
ui = A()
ui.show()
The problem here is that the preview function _prerun
updates the GUI state so the
second preview and the actual run are affected by the previous previews.
To restore the original GUI state, you can use a generator function.
@magicclass
class A:
...
@impl_preview(gaussian_filter)
def _prerun(self, sigma):
old = self.img # store current image
self.gaussian_filter(sigma) # run preview
yield # prerun called here
self.img = old # restore
Note
impl_preview
does NOT check if the preview function actually restored the GUI
state. The logic of the preview function is up to you.
Auto call
In the example above, it's nicer to auto-call the preview function. impl_preview
has an option auto_call=True
to implement this.
@magicclass
class A:
...
@impl_preview(gaussian_filter, auto_call=True)
def _prerun(self, sigma):
old = self.img # store current image
self.gaussian_filter(sigma) # run preview
yield # prerun called here
self.img = old # restore
In the auto-call mode, a checkbox (instead of an additional button) will be added to the dialog. Preview will be auto-called if the checkbox in checked.