I am trying to add a legend to my scatter plot with 13 classes, however, with my code below, I am only able to get the first label. Can you assist me in generating the full list to show up in the legend of the scatter plot?
Here is my example code:
from sklearn.datasets import make_blobs
from matplotlib import pyplot
from pandas import DataFrame
# generate 2d classification dataset
X, y = make_blobs(n_samples=1000, centers=13, n_features=2)
classes = [f"class {i}" for i in range(13)]
#fig = plt.figure()
plt.figure(figsize=(15, 12))
scatter = plt.scatter(
x=X[:,0],
y=X[:,1],
s = 20,
c = y,
cmap='Spectral'
#c=[sns.color_palette()[x] for x in y_train_new]
)
plt.gca().set_aspect('equal', 'datalim')
plt.legend(classes)
plt.title('Dataset', fontsize=24)
You can do that by replacing the plt.legend(classes) in your code by this line... I hope this is what you are looking for. I am using matplotlib 3.3.4.
plt.legend(handles=scatter.legend_elements()[0], labels=classes)
Output plot
Related
I am using matplotlib to plot a pie chart. I have added a legend to the chart. However, i would like to add a "Total" to the legend, to sum up the values of all the other categories. Hence the value of "Total" would not be a part of the pie chart, and would only be shown in the legend. Is it possible for me to do that? Thank you.
You can create 2 legends. On the second one, you can create/manipulate symbol/text/title as you want. Here is a runnable code that you can try.
from matplotlib import pyplot as plt
import matplotlib.patches as mpatches
import numpy as np
fig = plt.figure()
ax = fig.add_axes([0,0,1,1])
ax.axis('equal')
langs = ['C', 'C++', 'Java', 'Python', 'PHP']
students = [23,17,35,29,12]
ax.pie(students, labels = langs,autopct='%1.2f%%')
# first legend
lgn = plt.legend()
ax = plt.gca().add_artist(lgn)
# second legend
gold_patch = mpatches.Patch(color='gold', label='Total= 9999') # use your description text here
second_legend = plt.legend(handles=[gold_patch], loc=1, \
bbox_to_anchor=(0.5, 0.35, 0.55, 0.35)) # adjust location of legend here
second_legend.set_frame_on(False) # use True/False as needed
second_legend.set_title("Other categories")
plt.show()
The output plot:
I created a scatter plot in seaborn using seaborn.relplot, but am having trouble putting the legend all in one graph.
When I do this simple way, everything works fine:
import pandas as pd
import numpy as np
from scipy import stats
import matplotlib.pyplot as plt
import seaborn as sns
df2 = df[df.ln_amt_000s < 700]
sns.relplot(x='ln_amt_000s', y='hud_med_fm_inc', hue='outcome', size='outcome', legend='brief', ax=ax, data=df2)
The result is a scatter plot as desired, with the legend on the right hand side.
However, when I try to generate a matplotlib figure and axes objects ahead of time to specify the figure dimensions I run into problems:
a4_dims = (10, 10) # generating a matplotlib figure and axes objects ahead of time to specify figure dimensions
df2 = df[df.ln_amt_000s < 700]
fig, ax = plt.subplots(figsize = a4_dims)
sns.relplot(x='ln_amt_000s', y='hud_med_fm_inc', hue='outcome', size='outcome', legend='brief', ax=ax, data=df2)
The result is two graphs -- one that has the scatter plots as expected but missing the legend, and another one below it that is all blank except for the legend on the right hand side.
How do I fix this such? My desired result is one graph where I can specify the figure dimensions and have the legend at the bottom in two rows, below the x-axis (if that is too difficult, or not supported, then the default legend position to the right on the same graph would work too)? I know the problem lies with "ax=ax", and in the way I am specifying the dimensions as matplotlib figure, but I'd like to know specifically why this causes a problem so I can learn from this.
Thank you for your time.
The issue is that sns.relplot is a "Figure-level interface for drawing relational plots onto a FacetGrid" (see the API page). With a simple sns.scatterplot (the default type of plot used by sns.relplot), your code works (changed to use reproducible data):
df = pd.read_csv("https://vincentarelbundock.github.io/Rdatasets/csv/datasets/iris.csv", index_col=0)
fig, ax = plt.subplots(figsize = (5,5))
sns.scatterplot(x = 'Sepal.Length', y = 'Sepal.Width',
hue = 'Species', legend = 'brief',
ax=ax, data = df)
plt.show()
Further edits to legend
Seaborn's legends are a bit finicky. Some tweaks you may want to employ:
Remove the default seaborn title, which is actually a legend entry, by getting and slicing the handles and labels
Set a new title that is actually a title
Move the location and make use of bbox_to_anchor to move outside the plot area (note that the bbox parameters need some tweaking depending on your plot size)
Specify the number of columns
fig, ax = plt.subplots(figsize = (5,5))
sns.scatterplot(x = 'Sepal.Length', y = 'Sepal.Width',
hue = 'Species', legend = 'brief',
ax=ax, data = df)
handles, labels = ax.get_legend_handles_labels()
ax.legend(handles=handles[1:], labels=labels[1:], loc=8,
ncol=2, bbox_to_anchor=[0.5,-.3,0,0])
plt.show()
This code shows an Attribute error:
I am plotting errorbar plot for let's say 10 different datasets (huge datasets) from a file containing multiple datasets (let's say for different days), and I am showing the user an option (Checkbox) to remove or include a plot of the particular dataset (through GUI).
So for this, I just want to erase the current axes and at a later time want to redraw it again.
How can I do this?
Below is a simplified example to show what I need.
import matplotlib.pyplot as plt
import numpy as np
fig, ax = plt.subplots(1)
x, y, yerr = np.random.rand(3,10)
l = ax.errorbar(x, y, yerr, marker='s', mfc='red', mec='green', ms=20, mew=4)
canvas = fig.canvas
canvas.draw()
bkg = canvas.copy_from_bbox(ax.bbox)
plt.show()
plt.pause(1)
ax.clear()
canvas.restore_region(bkg)
ax.draw_artist(l)
# here it throws an AttributeError: 'ErrorbarContainer'
#object has no attribute 'draw'
I am trying to create a 3D Temperature plot vs Depth vs Time with a large .csv data-set. The example below is created in matlab. I want a similar output using Python 3.x with reverse scales on the Temperature and Depth axis.
Example output with a few mods needed
I have started off with the following code:
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
import pandas as pd
import seaborn as sns
# Get the data (csv file is hosted on the web)
data = pd.read_csv('C;\\Path\\TestData_Temp-Time-Depth_3DPlot.csv')
# Transform it to a long format
df = data.unstack().reset_index()
df.columns = ["X", "Y", "Z"]
# And transform the old column name in something numeric
df['X'] = pd.Categorical(df['X'])
df['X'] = df['X'].cat.codes
# Make the plot
fig = plt.figure()
ax = fig.gca(projection='3d')
ax.plot_trisurf(df['Y'], df['X'], df['Z'], cmap=plt.cm.jet, linewidth=0.2)
plt.show()
# to Add a color bar which maps values to colors.
surf = ax.plot_trisurf(df['Y'], df['X'], df['Z'], cmap=plt.cm.jet, linewidth=0.2)
fig.colorbar(surf, shrink=0.5, aspect=5)
plt.show()
# Rotate it
ax.view_init(30, 45)
plt.show()
# Other palette
ax.plot_trisurf(df['Y'], df['X'], df['Z'], cmap=plt.cm.jet, linewidth=0.01)
plt.show()
I am having issues understanding how to assign values from from csv to the x, y, z axis.
The example data I am using is formatted like:
csv data structure
Example data download: Download Example Data
Thank you in advance.
I have a dataset from which I intent to make a scatterplot. It consists of 2 columns, where the first column should be used as x, and the other as y, so that each dot = x[0 firstcolumn], x[0 secondcolumn].
However I keep getting "x and y must be same size", and I cannot make out how to plot this. Below is my latest attempt on making them the same size, however unsuccesful
import numpy as np
import matplotlib.pyplot as plt
X = numpy.loadtxt('data')
x = range(len(X))
plt.scatter(x,X, color='blue', label = "car")
plt.show()