来自熊猫交叉表的 Plotly 气泡图

Question

How can I plot a bubble chart from a dataframe that has been created from a pandas crosstab of another dataframe?

Imports;

import plotly as py
import plotly.graph_objects as go
from plotly.subplots import make_subplots

The crosstab was created using;

df = pd.crosstab(raw_data['Speed'], raw_data['Height'].fillna('n/a'))

The df contains mostly zeros, however where a number appears I want a point where the value controls the point size. I want to set the Index values as the x axis and the columns name values as the Y axis.

The df would look something like;

         10    20    30    40    50
1000     0     0    0      0     5
1100     0     0    0      7     0
1200     1     0    3      0     0
1300     0     0    0      0     0
1400     5     0    0      0     0

I've tried using scatter & Scatter like this;

fig.add_trace(go.Scatter(x=df.index.values, y=df.columns.values, size=df.values,
                         mode='lines'),
              row=1, col=3)

This returned a TypeError: 'Module' object not callable.

Any help is really appreciatted. Thanks

UPDATE

The answers below are close to what I ended up with, main difference being that I reference 'Speed' in the melt line;

df.reset_index()
df.melt(id_vars="Speed")
df.rename(columns={"index":"Engine Speed",
                    "variable":"Height",
                    "value":"Count"})
df[df!=0].dropna()

scale=1000

fig.add_trace(go.Scatter(x=df["Speed"], y=df["Height"],mode='markers',marker_size=df["Count"]/scale),
              row=1, col=3)

This works however my main problem now is that the dataset is huge and plotly is really struggling to deal with it.

Update 2

Using Scattergl allows Plotly to deal with the large dataset very well!

Answer 1

I recommend to use tidy format to represent your data. We say a dataframe is tidy if and only if

1. Each row is an observation
2. Each column is a variable
3. Each value must have its own cell

To create a more tidy-dataframe you can do

df = pd.crosstab(raw_data["Speed"], raw_data["Height"])
df.reset_index(level=0, inplace=True)
df.melt(id_vars=["Speed", "Height"], value_vars=["Counts"])

   Speed  Height  Counts
0   1000      10       2
1   1100      20       1
2   1200      10       1
3   1200      30       1
4   1300      40       1
5   1400      50       1

The next step is to do the actual plotting.

# when scale is increased bubbles will become larger
scale = 10 
# create the scatter plot
scatter = go.Scatter(
    x=df.Speed, 
    y=df.Height,
    marker_size=df.counts*scale,
    mode='markers')
fig = go.Figure(scatter)
fig.show()

This will create a plot as shown below.

Answer 2

If this is the case you can use plotly.express this is very similar to @Erik answer but shouldn't return errors.

import pandas as pd
import plotly.express as px
from io import StringIO

txt = """
        10    20    30    40    50
1000     0     0    0      0     5
1100     0     0    0      7     0
1200     1     0    3      0     0
1300     0     0    0      0     0
1400     5     0    0      0     0
"""

df = pd.read_csv(StringIO(txt), delim_whitespace=True)

df = df.reset_index()\
       .melt(id_vars="index")\
       .rename(columns={"index":"Speed",
                        "variable":"Height",
                        "value":"Count"})

fig = px.scatter(df, x="Speed", y="Height",size="Count")
fig.show()

UPDATE In case you got error please check your pandas version with pd.__version__ and try to check line by line this

df = pd.read_csv(StringIO(txt), delim_whitespace=True)

df = df.reset_index()

df = df.melt(id_vars="index")

df = df.rename(columns={"index":"Speed",
                        "variable":"Height",
                        "value":"Count"})

and report in which line it breaks.