Create appy2.py

appy2.py

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+# load up the libraries
+import panel as pn
+import pandas as pd
+import altair as alt
+from vega_datasets import data
+
+# we want to use bootstrap/template, tell Panel to load up what we need
+pn.extension(design='bootstrap')
+
+# we want to use vega, tell Panel to load up what we need
+pn.extension('vega')
+
+# create a basic template using bootstrap
+template = pn.template.BootstrapTemplate(
+    title='SI649 Walkthrough',
+)
+
+# the main column will hold our key content
+maincol = pn.Column()
+
+# add some markdown to the main column
+maincol.append("# Markdown Title")
+maincol.append("I can format in cool ways. Like **bold** or *italics* or ***both*** or ~~strikethrough~~ or `code` or [links](https://panel.holoviz.org)")
+maincol.append("I am writing a link [to the streamlit documentation page](https://docs.streamlit.io/en/stable/api.html)")
+maincol.append('![alt text](https://upload.wikimedia.org/wikipedia/commons/thumb/3/3e/Irises-Vincent_van_Gogh.jpg/314px-Irises-Vincent_van_Gogh.jpg)')
+
+# load up a dataframe and show it in the main column
+cars_url = "https://raw.githubusercontent.com/altair-viz/vega_datasets/master/vega_datasets/_data/cars.json"
+cars = pd.read_json(cars_url)
+temps = data.seattle_weather()
+
+maincol.append(temps.head(10))
+
+# create a basic chart
+hp_mpg = alt.Chart(cars).mark_circle(size=80).encode(
+    x='Horsepower:Q',
+    y='Miles_per_Gallon:Q',
+    color='Origin:N'
+)
+
+# dispaly it in the main column
+# maincol.append(hp_mpg)
+
+# create a basic slider
+simpleslider = pn.widgets.IntSlider(name='Simple Slider', start=0, end=100, value=0)
+
+# generate text based on slider value
+def square(x):
+    return f'{x} squared is {x**2}'
+
+
+# bind the slider to the function and hold the output in a row
+row = pn.Column(pn.bind(square,simpleslider))
+
+# add both slider and row
+maincol.append(simpleslider)
+maincol.append(row)
+
+# variable to track state of visualization
+flip = False
+
+# function to either return the vis or a message
+def makeChartVisible(val):
+    global flip  # grab the variable outside the function
+    if (flip == True):
+        flip = not flip             # flip to False
+        return pn.pane.Vega(hp_mpg) # return the vis
+    else:
+        flip = not flip             # flip to true and return text
+        return pn.panel("Click the button to see the chart")
+    
+# add a button and then create the binding
+btn = pn.widgets.Button(name='Click me')
+row = pn.Row(pn.bind(makeChartVisible, btn))
+
+# add button and new row to main column
+maincol.append(btn)
+maincol.append(row)
+
+# create a base chart
+basechart = alt.Chart(cars).mark_circle(size=80,opacity=0.5).encode(
+    x='Horsepower:Q',
+    y='Acceleration:Q',
+    color="Origin:N"
+)
+
+# create something to hold the base chart
+currentoption = pn.panel(basechart)
+
+# create a selection widget
+select = pn.widgets.Select(name='Select', options=['Horsepower','Acceleration','Miles_per_Gallon'])
+
+# create a function to modify the basechart that is being
+# held in currentoption
+def changeOption(val):
+    # grab what's there now
+    chrt = currentoption.object
+    # change the encoding based on val
+    chrt = chrt.encode(
+        y=val+":Q"
+    )
+    # replace old chart in currentoption with new one
+    currentoption.object = chrt
+
+# append the selection
+maincol.append(select)
+# append the binding (in thise case nothing is being returned by changeOption, so...)
+chartchange = pn.Row(pn.bind(changeOption, select))
+# ... we need to also add the chart
+maincol.append(chartchange)
+maincol.append(currentoption)
+
+# add the main column to the template
+template.main.append(maincol)
+
+# Indicate that the template object is the "application" and serve it
+template.servable(title="SI649 Walkthrough")