CODEWITHSUNDEEP
pythonmatplotlib
Script kiddies
Script kiddies

Reputation: 157

Matplotlib Annotation not working

I have not used matplotlib before- i have downloaded the libary and read the documentation. I am trying to display the value on top of the bar using the code below. However, the value does not display

import numpy as np
import matplotlib.pyplot as plt
data = [ ("data1", 34), ("data5", 22),
        ("data12", 11), ( "data8", 28),
        ("data53", 57), ( "data11", 39),
        ("data12", 23), ( "data15", 98)]
N = len(data)
x = np.arange(1,N+1)
y = [ num for (s, num) in data ]
labels = [ s for (s, num) in data ]
width = 1
bar1 = plt.bar( x, y, width, color="y" )
plt.ylabel( 'Intensity' )
plt.xticks(x + width/2.0, labels )

for x, y in zip(x, y):
    plt.annotate("%i" % y, (x, y + 200), ha= 'center')

plt.show()

Any help is greatly appreciated

Upvotes: 4

Views: 11876

Answers (1)

Ffisegydd
Ffisegydd

Reputation: 53678

Your issue is simply that the position of your annotations is way above your current y-axis limits, due to you adding 200 to the y-position.

import numpy as np
import matplotlib.pyplot as plt
data = [ ("data1", 34), ("data5", 22),
        ("data12", 11), ( "data8", 28),
        ("data53", 57), ( "data11", 39),
        ("data12", 23), ( "data15", 98)]
N = len(data)
x = np.arange(1,N+1)
y = [ num for (s, num) in data ]
labels = [ s for (s, num) in data ]
width = 1
bar1 = plt.bar( x, y, width, color="y" )
plt.ylabel( 'Intensity' )
plt.xticks(x + width/2.0, labels )

y_shift = 5
x_shift = width/2.0
for x, y in zip(x, y):
    plt.annotate("%i" % y, (x + x_shift, y + y_shift), ha= 'center')

plt.ylim(0,110)

plt.show()

Simply changing the vertical offset to a more reasonable number (chosen above as y_shift = 5) fixes the height issue, but you also need to add width/2.0 to the x-position to get the text in the centre of the bar (assuming that's what you want). I've also added plt.ylim(0,110) to the end to shift the y-limits a bit to show the number for the biggest bar.

Example plot

Upvotes: 5

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