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Bar chart using Plotly in Python
  • Last Updated : 04 Feb, 2021

Plotly is a Python library which is used to design graphs, especially interactive graphs. It can plot various graphs and charts like histogram, barplot, boxplot, spreadplot, and many more. It is mainly used in data analysis as well as financial analysis. Plotly is an interactive visualization library. 

Bar Chart 

In a bar chart the data categories are displayed on the vertical axis and the data values are displayed on the horizontal axis. Labels are easier to display and with a big data set they impel to work better in a narrow layout such as mobile view. 

Syntax: plotly.express.bar(data_frame=None, x=None, y=None, color=None, facet_row=None, facet_col=None, facet_col_wrap=0, hover_name=None, hover_data=None, custom_data=None, text=None, error_x=None, error_x_minus=None, error_y=None, error_y_minus=None, animation_frame=None, animation_group=None, category_orders={}, labels={}, color_discrete_sequence=None, color_discrete_map={}, color_continuous_scale=None, range_color=None, color_continuous_midpoint=None, opacity=None, orientation=None, barmode=’relative’, log_x=False, log_y=False, range_x=None, range_y=None, title=None, template=None, width=None, height=None)

Parameters:

NameDescription
data_frame This argument needs to be passed for column names (and not keyword names) to be used. Array-like and dict are tranformed internally to a pandas DataFrame. Optional: if missing, a DataFrame gets constructed under the hood using the other arguments.
xEither a name of a column in data_frame, or a pandas Series or array_like object. Values from this column or array_like are used to position marks along the x axis in cartesian coordinates. Either x or y can optionally be a list of column references or array_likes, in which case the data will be treated as if it were ‘wide’ rather than ‘long’.
yEither a name of a column in data_frame, or a pandas Series or array_like object. Values from this column or array_like are used to position marks along the y axis in cartesian coordinates. Either x or y can optionally be a list of column references or array_likes, in which case the data will be treated as if it were ‘wide’ rather than ‘long’.
color Either a name of a column in data_frame, or a pandas Series or array_like object. Values from this column or array_like are used to assign color to marks.

Bar chart with Plotly Express

In this example, we are going to use Plotly express to plot a bar chart.



Python3




import plotly.express as px
import numpy
 
# creating random data through randomint
# function of numpy.random
np.random.seed(42)
   
random_x= np.random.randint(1, 101, 100)
random_y= np.random.randint(1, 101, 100)
 
fig = px.bar(random_x, y = random_y)
fig.show()

 Output:

 

Bar chart with Long and wide Format Data

Example 1: In this example, we will use the iris data set and convert it into the dataframe to plot bar chart.

Python3




import plotly.express as px
 
df = px.data.iris()
 
fig = px.bar(df, x = "sepal_width", y = "sepal_length")
fig.show()

 Output:



Example 2: In this example, we will see long-form data. long-form data has one row per observation, and one column per variable. This is suitable for storing and displaying multivariate data i.e. with dimensions greater than 2. This format is sometimes called “tidy”.

Python3




import plotly.express as px
long_df = px.data.medals_long()
 
fig = px.bar(long_df, x = "nation", y = "count",
             color = "medal", title = "Long-Form Input")
fig.show()

Output:

Example 3: In this example, we will see wide-from data. wide-form data has one row per value of one of the first variable, and one column per value of the second variable. This is suitable for storing and displaying 2-dimensional data.

Python3




import plotly.express as px
df = px.data.medals_wide()
 
fig = px.bar(df, x="nation",
             y=["gold", "silver", "bronze"],
             title="Wide Form Data")
fig.show()

Output:

Showing Facetted subplots

In plotly, to create the facetted subplots facet_row argument is used, where different values correspond to different rows of the dataframe columns.

Example:

Python3




import plotly.express as px
 
df = px.data.iris()
 
fig = px.bar(df, x="sepal_width", y="sepal_length",
             color="species", barmode="group",
             facet_row="species", facet_col="species_id")
 
fig.show()

 Output:

Customizing bar charts

By using keyword arguments the bar mode can be customized. Let’s see the examples given below:

Example 1: In this example, the bar is customizing according to the color attributes. 

Python3




import plotly.express as px
 
df = px.data.iris()
 
fig = px.bar(df, x="sepal_width", y="sepal_length", color="species")
fig.show()

 Output:

Example 2: In this example, we will use barmode = “group”. With “group”, the bars are grouped with one another

Python3




import plotly.express as px
 
df = px.data.iris()
 
fig = px.bar(df, x="sepal_width", y="sepal_length",
             color="species", barmode = 'group')
fig.show()

Output:

Example 3: Here, we will use “overlay” With “overlay”, the bars are overlaid with another. Here we see easly “opacity” to see multiple bars.

Python3




import plotly.express as px
 
df = px.data.iris()
 
fig = px.bar(df, x="sepal_width", y="sepal_length",
             color="species", barmode='overlay')
fig.show()

Output:

 

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