Understanding the Problem: Removing Text from Bar Chart Bars in Plotly

In this article, we will explore a common problem when creating bar charts with Plotly. The issue is that certain text, such as department names or chemical names, is displayed on top of the bars in the chart. We’ll delve into why this happens and provide solutions to remove these texts.

Problem Explanation

The provided code snippet creates a stacked bar chart using Plotly’s plot_ly function. However, when you hover over each bar, you notice that the text “Department” or “Chemical Name” is displayed on top of the bars. This text appears to be part of the data being passed to Plotly, but it doesn’t belong in the visual representation of the chart.

Understanding Data and Text Positioning

When creating a bar chart with Plotly, you’re passing data to the plot_ly function using various arguments such as x, y, name, etc. These arguments specify which columns in your dataset correspond to which aspect of the chart (e.g., x-axis values, y-axis values). The text that appears on top of each bar is called a “text” and it’s typically passed using the text argument.

In this case, we’re passing two datasets: one for the demand per section and another for the amount available. We’re also specifying text to be displayed based on the department name or chemical name.

Solution: Adjusting Text Position

To remove these unwanted texts, we need to adjust their position. Plotly provides a way to do this using the textposition argument. This argument specifies where the text should appear relative to each data point.

By setting textposition = "none", we’re telling Plotly not to display any text on top of the bars. Instead, we want the text to be displayed only when we hover over a particular bar or in the tooltip that appears when we do so.

Here’s an updated version of the code with this adjustment:

fig <- plot_ly(x = ~`Element Name`,text = ~Department, data = dp) %>% 
  add_bars(y = ~`DemandCourse`, 
           name = "Demand", 
           textposition = "none",          # Adjusted here
           hovertemplate = paste0("Chemical Name: %{x}&lt;br&gt;", 
                                  "Demand: %{y}&lt;br&gt;",
                                  "Department: %{text}&lt;extra&gt;&lt;/extra&gt;")) %>% 
  add_bars(y = ~`Amount Available`,
           name = "Amount Available", 
           textposition = "none",          # Adjusted here
           hovertemplate = paste0("Chemical Name: %{x}&lt;br&gt;",  
                                  "Available Amount: %{y}&lt;br&gt;",
                                  "Department: %{text}&lt;extra&gt;&lt;/extra&gt;")) %>% 
  layout(barmode = "stack",                # Removed showLegend
         xaxis = list(title = "Element Name", tickangle=45),
         yaxis = list(title = "Amount Available"),
         title = "Amount and Demand per Element")

Conclusion

In this article, we’ve explored a common issue when creating bar charts with Plotly: displaying unwanted text on top of the bars. By understanding how data and text positioning work in Plotly, we were able to adjust the code to remove these texts using the textposition argument.

With this solution, you should be able to create beautiful and informative bar charts without any extraneous text cluttering them up.

Additional Considerations

• If you have a lot of data points, adjusting textposition can sometimes lead to issues with readability. In such cases, it might be better to use more advanced visualization techniques like faceting or grouping.
• Plotly offers many other customization options for your chart. Experiment with different layouts and visualizations to find the perfect fit for your needs.

Code Blocks

Here is an updated version of the code that takes advantage of some additional features:

fig <- plot_ly(x = ~`Element Name`,text = ~Department, data = dp) %>% 
  add_bars(y = ~`DemandCourse`, 
           name = "Demand", 
           hovertemplate = "Chemical Name: %{x}&lt;br&gt;Demand: %{y}%lt<br&gt;Department: %{text}&lt;extra&gt;&lt;/extra&gt;",
           type = "bar") %>% 
  add_bars(y = ~`Amount Available`,
           name = "Amount Available",
           hovertemplate = "Chemical Name: %{x}&lt;br&gt;Available Amount: %{y}%lt<br&gt;Department: %{text}&lt;extra&gt;&lt;/extra&gt;",
           type = "bar") %>% 
  layout(barmode = "stack",                # Removed showLegend
         xaxis = list(title = "Element Name", tickangle=45),
         yaxis = list(title = "Amount Available"),
         title = "Amount and Demand per Element")

In this updated code, we’ve used the type argument to specify that both bars should be of type bar. This will help avoid unnecessary processing when displaying the plot.

Last modified on 2023-11-12