Dear AvratanuBiswas,
Thank you four your reply ! 
This is my full code :
#__________________________
## Import libraries
#__________________________
import pandas as pd
import numpy as np
import streamlit as st
from PIL import Image
import altair as alt
from datetime import datetime
#__________________________
## Import and clean dataset
#__________________________
# Transform XLSX file to CSV to load data properly
df = pd.read_excel(accessfile_etc.xlsx')
# Split column notification into different column and rename it
df = df.join(df['Notification'].str.split(';', expand= True))
df = df.rename({0: 'Contract', 1: 'Action', 2: 'Part_number', 3: 'Product', 4: 'Ship_to', 5: 'Date'}, axis=1)
# Remove useless column
del df['Notification']
del df['Date de notifification']
#Remove Contract/Contrat N° from Contract column
df['Contract'] = df.Contract.str.replace('Contract N°' , '')
df['Contract'] = df.Contract.str.replace('Contrat N°' , '')
# Check and transform date type
print(type('Date de traitement'))
df['Date de traitement'] = pd.to_datetime(df['Date de traitement'], format='%Y%m%d')
df['Date'] = pd.to_datetime(df['Date'], format='%d/%m/%Y')
print(df.dtypes)
# Count Date
df['Count_date'] = df['Date'].map(df['Date'].value_counts())
# Count Ship_to
df['Count_ship'] = df['Ship_to'].map(df['Ship_to'].value_counts())
## Application creation
#______________________
# Data creation
HOME_MSG = ('Welcome to the app')
APP_TITLE = 'APPLICATIF SUP'
APP_HEADER = 'Tracking tool '
SIDEBAR_TITLE = 'Menu'
MENU_MSG = 'Choose data you want to view'
MENU_CHOICES = ['Home','Sales Administration','Status','Product']
logo_one = Image.open('accessfile_etc')
logo_two = Image.open('accessfile2_etc')
TITLE_SALES = 'What is a Sup?'
SUBTITLE_SALES ='What to do whit it ?'
def load_data(nrows):
data = df
return data
@st.cache
#data_load_state.text("Done! (using st.cache)")
def home_msg():
st.write(HOME_MSG)
def main():
#Set image 1
st.sidebar.image(logo_one)
#Set Sidebar title
st.sidebar.title(SIDEBAR_TITLE)
#Set Menu
menu_action =
st.sidebar.selectbox(MENU_MSG,MENU_CHOICES)
if menu_action=='Home':
#Set App title and logo two
col1, col2 = st.columns([1,7])
with col2:
st.title(APP_TITLE)
with col1:
st.image(logo_two, width=120)
#Set App header
st.header(APP_HEADER)
if menu_action=='Sales Administration':
# EXPLAIN WHAT IS APPLICATIF SUP AND HOW TO DEAL WITH IT
st.title(TITLE_SALES)
st.subheader(SUBTITLE_SALES)
st.markdown("We have to **verify** each action : ")
texts = ["- Go on website : link.com","- Download docs.","- Check if ok.","- If ok, action1.","- If not, action2"]
st.write(texts[0])
st.write(texts[1])
st.write(texts[2])
st.write(texts[3])
st.write(texts[4])
if menu_action=='Status':
st.write('This is the full dataset. You can find here each notification received, whom traited it and when.')
# DATAFRAME :
# Create a text element and let the reader know the data is loading.
data_load_state = st.text('Loading data...')
# Load 10,000 rows of data into the dataframe.
df = load_data(1000)
# Notify the reader that the data was successfully loaded.
data_load_state.text('Loading data...done!')
st.subheader('Data to analyse :')
## Create filters on ship_to and part number
# Create ship to list with all values :
ship_to = df['Ship_to'].unique().tolist()
# Create a table to have filters side by side :
col1, col2 = st.columns([1,1])
with col2:
selected_shipto = st.multiselect(
'Which ship to would like to choose ? ',
ship_to)
with col1:
selected_pn = st.text_input(
'Which PN are you looking for ? ',
)
# Create filter_function for df
df_filtered = df[
df['Part_number'].str.contains(selected_pn) &
df['Ship_to'].isin(selected_shipto)]
# Avoid empty dataframe when no filters selected :
def filtered_data(df):
if df_filtered.empty :
st.write(df)
else : st.write(df_filtered)
return df_filtered
# Write data frame :
st.write(filtered_data)
## Graph parts
##_______
# Altair chart n.1 :
#st.subheader('Action done by date :')
# Filtered chart on ship_to / pn
#c = alt.Chart(df).mark_circle().encode(
# x='Date', y='Count_date', size='Action', color ='Action',
# tooltip=["Date", "Count_date", "Action"])
#st.altair_chart(c, use_container_width=True)
# Altair chart n.2 :
#st.subheader('Action done by ship to :')
# Filtered chart on part number
#c = alt.Chart(df).mark_bar().encode(
# x='Ship_to', y='Count_ship', tooltip=["Ship_to", "Count_ship", "Action"]).configure_mark(
# opacity=0.2,
# color='orange').interactive()
#st.altair_chart(c, use_container_width=True)
if __name__ == '__main__':
main()
Thank you for your help. I think (maybe) that I can not filter the dataset on PN if Ship to is not filtered. I tried to create a function if Ship to filter is empty. It works. But then I can not filter only on Ship to. An infinite loop ahha. 
