# Visual check PRFs with an user interface
## Open the user interface
Following previous steps, PRFs have been calculated and save to SAC files in a folder named as the station name.
```
net.sta
├── 2018.229.15.35.02_P_R.sac
├── 2018.229.15.35.02_P_T.sac
├── 2018.229.22.06.55_P_R.sac
├── 2018.229.22.06.55_P_T.sac
│......
```
For example, PRFs were saved in folder `net.sta`. the file name of the PRF must be in `%Y.%j.%H.%M.%S_P_[RT].sac`. Now input following command to open the UI to browse the PRFs and reject poor PRFs.
```
$ pickrf /path/to/net.sta
```
The window will open as following image. Each page will display 20 PRFs. You can press `z` and `c` hotkey or click `previous` and `next` button for turning pages.
## Operations
Directly click PRFs on the interface to set up them to 'poor' PRFs. The PRFs will turn gray when you click a PRF. If you click again, it will restored to a 'good' PRF.
When you have selected all PRFs, please click `finish` button to delete all 'poor' PRFs. Then a list file named as `net.stafinallist.dat` will be generated automatically in the folder, which include following columns
- Event name: the event name with format as `%Y.%j.%H.%M.%S`.
- Phase: the phase name (same as that in file name).
- Event latitude
- Event longitude
- Event depth
- Epicenter distance in degree
- Back-azimuth
- Ray-parameters in s/km
- Magnitude
- Gaussian factor
```{note}
This list file is **very important** for derived method such as H-k stacking and CCP stacking.
```
## Other functions
### enlarge and reduce visual amplitudes of the waveforms
Buttons of `Amp enlarge` and `Amp reduce` are available to control the visual amplitudes.
### Preview all PRFs
the `space` hotkey and `preview` button provide a function to plot all 'good' PRFs. Use `ctrl+s` on Linux/Windows and `cmd+s` on MacOS to save this figure as a PDF file.
## Keymap
| Key | Function |
| ------ | ------ |
| z | Page up |
| c | Page down |
| space | Preview all good PRFs |
|ctrl+s or cmd+s | Save preview |
## Re-calculation of RFs
As a final-list saved into RF output path, events information of RFs can be invoked for re-calculation if we need to change some parameters, such as gauss factor, bandwidth of filter or deconvolution method. After version 1.2.14, the `prf` command introduce a new option of `-f` for re-calculation using events in the final-list.