5

我正在开发一个streamlit应用程序，其中包含一个带有 10 个选项的多选小部件。是否有另一种方法可以添加一个选择所有选项的按钮以避免一一选择？

我尝试向多选添加上一个按钮，但使用另一个小部件会重置选择。这是一个示例代码：

import streamlit as st

if st.sidebar.button('Add all years'):
    year_filter = st.sidebar.multiselect('Select a year',[2000,2001,2002,2003,2004], default=[2000,2001,2002,2003,2004])
else:
    year_filter = st.sidebar.multiselect('Select a year',[2000,2001,2002,2003,2004], default=[2000])

type_filter = st.sidebar.multiselect('Choose a type',['Control','Experimental'], default=['Experimental'])

st.write(year_filter, type_filter)
4

1 回答 1

3

有一种使用方法state：

import streamlit as st
from streamlit.ReportThread import get_report_ctx
from streamlit.hashing import _CodeHasher
from streamlit.server.Server import Server


class _SessionState:
    def __init__(self, session, hash_funcs):
        """Initialize SessionState instance."""
        self.__dict__["_state"] = {
            "data": {},
            "hash": None,
            "hasher": _CodeHasher(hash_funcs),
            "is_rerun": False,
            "session": session,
        }

    def __call__(self, **kwargs):
        """Initialize state data once."""
        for item, value in kwargs.items():
            if item not in self._state["data"]:
                self._state["data"][item] = value

    def __getitem__(self, item):
        """Return a saved state value, None if item is undefined."""
        return self._state["data"].get(item, None)
        
    def __getattr__(self, item):
        """Return a saved state value, None if item is undefined."""
        return self._state["data"].get(item, None)

    def __setitem__(self, item, value):
        """Set state value."""
        self._state["data"][item] = value

    def __setattr__(self, item, value):
        """Set state value."""
        self._state["data"][item] = value
    
    def clear(self):
        """Clear session state and request a rerun."""
        self._state["data"].clear()
        self._state["session"].request_rerun()
    
    def sync(self):
        """Rerun the app with all state values up to date from the beginning to fix rollbacks."""

        # Ensure to rerun only once to avoid infinite loops
        # caused by a constantly changing state value at each run.
        #
        # Example: state.value += 1
        if self._state["is_rerun"]:
            self._state["is_rerun"] = False
        
        elif self._state["hash"] is not None:
            if self._state["hash"] != self._state["hasher"].to_bytes(self._state["data"], None):
                self._state["is_rerun"] = True
                self._state["session"].request_rerun()

        self._state["hash"] = self._state["hasher"].to_bytes(self._state["data"], None)


def _get_session():
    session_id = get_report_ctx().session_id
    session_info = Server.get_current()._get_session_info(session_id)

    if session_info is None:
        raise RuntimeError("Couldn't get your Streamlit Session object.")
    
    return session_info.session


def _get_state(hash_funcs=None):
    session = _get_session()

    if not hasattr(session, "_custom_session_state"):
        session._custom_session_state = _SessionState(session, hash_funcs)

    return session._custom_session_state


def main():
    state = _get_state()

    if state.previous_years_selected is None:
        state.previous_years_selected = [2000]
    
    if st.sidebar.button('Add all years'):
        year_filter = st.sidebar.multiselect('Select a year', [2000,2001,2002,2003,2004], default=[2000,2001,2002,2003,2004])
    else:
        year_filter = st.sidebar.multiselect('Select a year', [2000,2001,2002,2003,2004], default=state.previous_years_selected)

    # The next default (in case no one clicks on "Add all years")
    # will be the current years selected
    state.previous_years_selected = year_filter

    state.sync()


if __name__ == "__main__":
    main()

该_StateSession对象在 Streamlit 的重新加载过程中保留数据，这意味着如果您与小部件交互，页面会重新加载，但会state保留信息。
在这里，我们保留上次与“年份选择器”交互期间选择的年份的信息，并将其作为下次重新加载 ( default=state.previous_years_selected) 的默认值。

您可以将所需的任何数据添加到state对象。在修改它之前确保它确实存在：

if state.previous_years_selected is None:
    state.previous_years_selected = [2000]
于 2020-07-31T09:36:26.510 回答