How to plot a histogram of a single dataframe column and exclude 0s

Question

I have a huge dataframe that looks like this:

                   Date   value
1   2022-01-01 00:00:00   0.000
2   2022-01-01 01:00:00   0.000
3   2022-01-01 02:00:00   0.000
4   2022-01-01 08:00:00   0.058
5   2022-01-01 09:00:00   4.419
6   2022-01-01 10:00:00  14.142

I want to only plot in a histogram the column ‘value’ but without the 0 values. How do I do that?

I have tried :

plt.hist(df['value' >0], bins=50)

plt.hist(df['value' =! 0], bins=50)

but no luck. Any ideas?

Many thanks

Asked By: mariancatholic

||

Source

Answer 1

There’s a syntax error with df['value' > 0] — needs to be either df[df['value'] > 0] or df[df.value > 0].

The idea is that you create a boolean index with df.value:

>>> df.value > 0
0    False
1     True
2    False
3     True
4     True
5     True
Name: value, dtype: bool

And then use that index on df to retrieve the True indexes:

>>> df[df.value > 0]
date    value
1   2022/01/01  0.100
3   2022/01/01  0.058
4   2022/01/01  4.419
5   2022/01/01  14.142

On the plotting side, you can also plot directly with pandas:

>>> df[df.value > 0].plot.hist(bins=50)

Answered By: tdy

How to plot a histogram of a single dataframe column and exclude 0s

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