Adding value labels on a matplotlib bar chart

Question

I got stuck on something that feels like should be relatively easy  The code I bring below is a sample based on a larger project I m working on  I saw no reason to post all the details  so please accept the data structures I bring as is   Basically  I m creating a bar chart  and I just can figure out how to add value labels on the bars  in the center of the bar  or just above it   Been looking at samples around the web but with no success implementing on my own code  I believe the solution is either with  text  or  annotate   but I  a  don t know which one to use  and generally speaking  haven t figured out when to use which   b  can t see to get either to present the value labels  Would appreciate your help  my code below  Thanks in advance   import numpy as np import pandas as pd import matplotlib pyplot as plt pd set option  display mpl style    default     matplotlib inline    Bring some raw data  frequencies    6  16  75  160  244  260  145  73  16  4  1     In my original code I create a series and run on that     so for consistency I create a series from the list  freq series   pd Series from array frequencies   x labels    108300 0  110540 0  112780 0  115020 0  117260 0  119500 0               121740 0  123980 0  126220 0  128460 0  130700 0     Plot the figure  plt figure figsize  12  8   fig   freq series plot kind  bar   fig set title  Amount Frequency   fig set xlabel  Amount       fig set ylabel  Frequency   fig set xticklabels x labels

User · Answer

If you want to just label the data points above the bar, you could use plt.annotate()

My code:

import numpy as np
import matplotlib.pyplot as plt

n = [1,2,3,4,5,]
s = [i**2 for i in n]
line = plt.bar(n,s)
plt.xlabel('Number')
plt.ylabel("Square")

for i in range(len(s)):
    plt.annotate(str(s[i]), xy=(n[i],s[i]), ha='center', va='bottom')

plt.show()

By specifying a horizontal and vertical alignment of 'center' and 'bottom' respectively one can get centered annotations.

User · Answer

If you only want to add Datapoints above the bars  you could easily do it with    for i in range len frequencies      your number of bars     plt text x   x values i -0 25   takes your x values as horizontal positioning argument      y   y values i  1   takes your y values as vertical positioning argument      s   data labels i     the labels you want to add to the data     size   9    font size of datalabels

User · Answer

Building off the above  great   answer  we can also make a horizontal bar plot with just a few adjustments     Bring some raw data  frequencies    6  -16  75  160  244  260  145  73  16  4  1   freq series   pd Series frequencies   y labels    108300 0  110540 0  112780 0  115020 0  117260 0  119500 0               121740 0  123980 0  126220 0  128460 0  130700 0     Plot the figure  plt figure figsize  12  8   ax   freq series plot kind  barh   ax set title  Amount Frequency   ax set xlabel  Frequency   ax set ylabel  Amount       ax set yticklabels y labels  ax set xlim -40  300    expand xlim to make labels easier to read  rects   ax patches    For each bar  Place a label for rect in rects        Get X and Y placement of label from rect      x value   rect get width       y value   rect get y     rect get height     2        Number of points between bar and label  Change to your liking      space   5       Vertical alignment for positive values     ha    left         If value of bar is negative  Place label left of bar     if x value  lt  0            Invert space to place label to the left         space    -1           Horizontally align label at right         ha    right         Use X value as label and format number with one decimal place     label       1f   format x value         Create annotation     plt annotate          label                         Use  label  as label          x value  y value             Place label at end of the bar         xytext  space  0              Horizontally shift label by  space          textcoords  offset points     Interpret  xytext  as offset in points         va  center                    Vertically center label         ha ha                         Horizontally align label differently for                                       positive and negative values   plt savefig  image png

User · Answer

Firstly freq series plot returns an axis not a figure so to make my answer a little more clear I ve changed your given code to refer to it as ax rather than fig to be more consistent with other code examples  You can get the list of the bars produced in the plot from the ax patches member  Then you can use the technique demonstrated in this matplotlib gallery example to add the labels using the ax text method  import numpy as np import pandas as pd import matplotlib pyplot as plt    Bring some raw data  frequencies    6  16  75  160  244  260  145  73  16  4  1    In my original code I create a series and run on that     so for consistency I create a series from the list  freq series   pd Series from array frequencies   x labels    108300 0  110540 0  112780 0  115020 0  117260 0  119500 0              121740 0  123980 0  126220 0  128460 0  130700 0     Plot the figure  plt figure figsize  12  8   ax   freq series plot kind  bar   ax set title  Amount Frequency   ax set xlabel  Amount       ax set ylabel  Frequency   ax set xticklabels x labels   rects   ax patches    Make some labels  labels     quot label d quot    i for i in xrange len rects     for rect  label in zip rects  labels       height   rect get height       ax text rect get x     rect get width     2  height   5  label              ha  center   va  bottom    This produces a labeled plot that looks like

User · Answer

Based on a feature mentioned in this answer to another question I have found a very generally applicable solution for placing labels on a bar chart  Other solutions unfortunately do not work in many cases  because the spacing between label and bar is either given in absolute units of the bars or is scaled by the height of the bar  The former only works for a narrow range of values and the latter gives inconsistent spacing within one plot  Neither works well with logarithmic axes  The solution I propose works independent of scale  i e  for small and large numbers  and even correctly places labels for negative values and with logarithmic scales because it uses the visual unit points for offsets  I have added a negative number to showcase the correct placement of labels in such a case  The value of the height of each bar is used as a label for it  Other labels can easily be used with Simon s for rect  label in zip rects  labels  snippet  import numpy as np import pandas as pd import matplotlib pyplot as plt    Bring some raw data  frequencies    6  -16  75  160  244  260  145  73  16  4  1     In my original code I create a series and run on that    so for consistency I create a series from the list  freq series   pd Series from array frequencies   x labels    108300 0  110540 0  112780 0  115020 0  117260 0  119500 0              121740 0  123980 0  126220 0  128460 0  130700 0     Plot the figure  plt figure figsize  12  8   ax   freq series plot kind  bar   ax set title  Amount Frequency   ax set xlabel  Amount       ax set ylabel  Frequency   ax set xticklabels x labels    def add value labels ax  spacing 5        quot  quot  quot Add labels to the end of each bar in a bar chart       Arguments          ax  matplotlib axes Axes   The matplotlib object containing the axes             of the plot to annotate          spacing  int   The distance between the labels and the bars       quot  quot  quot         For each bar  Place a label     for rect in ax patches            Get X and Y placement of label from rect          y value   rect get height           x value   rect get x     rect get width     2            Number of points between bar and label  Change to your liking          space   spacing           Vertical alignment for positive values         va    bottom             If value of bar is negative  Place label below bar         if y value  lt  0                Invert space to place label below             space    -1               Vertically align label at top             va    top             Use Y value as label and format number with one decimal place         label    quot    1f  quot  format y value             Create annotation         ax annotate              label                         Use  label  as label              x value  y value             Place label at end of the bar             xytext  0  space              Vertically shift label by  space              textcoords  quot offset points quot     Interpret  xytext  as offset in points             ha  center                    Horizontally center label             va va                         Vertically align label differently for                                           positive and negative values      Call the function above  All the magic happens there  add value labels ax   plt savefig  quot image png quot    Edit  I have extracted the relevant functionality in a function  as suggested by barnhillec  This produces the following output   And with logarithmic scale  and some adjustment to the input data to showcase logarithmic scaling   this is the result

[python] Adding value labels on a matplotlib bar chart

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