[FIXED] Plotting strings as axis in matplotlib

Issue

I have a pandas DataFrame similar to :

Species  Count1 Count2 
AGREP      2       10
GYLEP      4       6
POAPRA     2       8
EUPESU     1       11

and I want to make a line plot of species vs. Count 1 with the x-axis being the species and the y-axis as Count 1.

I try to use the code:

import matplotlib.pyplot as plt
plt.plot(df.Species,df.Count1)

but this returns the error:

ValueError: could not convert string to float

I want to eventually only chose certain species to plot as well against both counts. For example, I want to plot AGREP and EUPESUS on the x axis against both Count 1 and Count 2 as the y axis. Again though, it won't plot the string as the axis name.

Solution

You can set those strings as index and just use the pandas.DataFrame .plot method.

import pandas as pd

# your data
# ===================================

df


  Species  Count1  Count2
0   AGREP       2      10
1   GYLEP       4       6
2  POAPRA       2       8
3  EUPESU       1      11


# plot
# ===================================
df.set_index('Species').plot()

df.set_index('Species').loc[['AGREP', 'EUPESU']].plot()

Answered By - Jianxun Li