Question: I understand if we want to pass data from pageA to pageB, we can use this

```
Navigator.pushNamed(context, PageB.ROUTE,arguments:pageAData);

```

If we want to pass data from pageA to pageE, what are the best way to achieve it?

In my app, it has a submit button in pageE. Once it is clicked, I want all data(pageA to pageD) submitted to server.

Answer: 
What you are looking for is [`pandas.DataFrame.applymap`](https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.applymap.html), which applies a function element-wise:

```
df.applymap(lambda x: -1 if x < low else (1 if x > high else 0))

```

The method [`pandas.DataFrame.apply`](https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.apply.html) applies a function along a given axis (default is column-wise).
You are sending the lambda the full dataframe, but you need to send it a column:

```
for col in df.columns:
    df[col].apply(lambda x: -1 if x < low else (1 if x > high else 0))

```