Plot a graph of a DataFrame of Timestamps

Question

I got a .csv-file containing lists of time spans like this:

00:00:00.000580;00:00:00.000893;00:00:00.001355;00:00:00.001767;00:00:00.001973;00:00:00.002694; 00:00:00.000069;00:00:00.000689;00:00:00.000873;00:00:00.001097;00:00:00.001920;00:00:00.002563; 00:00:00.000812;00:00:00.001307;00:00:00.001701;00:00:00.002561;00:00:00.003196;00:00:00.003600; 00:00:00.000702;00:00:00.001229;00:00:00.001750;00:00:00.002014;00:00:00.002633;00:00:00.003152; 00:00:00.000776;00:00:00.001774;00:00:00.001989;00:00:00.002115;00:00:00.002504;00:00:00.003228;

...

I'd like to use a jupyter notebook and pandas to read in this file and print a simple graph of the data. This is the code I'm using:

import pandas as pd

inputFile = "D:\\times.csv"

names = ['First', 'Second', 'Third', 'Fourth', 'Fivth', 'Sixth'] 
usecols = [0,1,2,3,4,5]
data = pd.read_csv(inputFile, usecols=usecols, sep=';', header=None, names=names, parse_dates=True)

#data.head()
data.plot.bar()

Whenever I run my notbook, I get an error message

TypeError: Empty 'DataFrame': no numeric data to plot

It seems the csv-file is imported correctly, since I can write out the content of my DataFrame using data.head() and it looks ok.

What do I need to do to plot a graph from my data?

Edit:

This is what I get from data.info():

RangeIndex: 200 entries, 0 to 199
Data columns (total 6 columns):
First 200 non-null object
Second 200 non-null object
Third 200 non-null object
Fourth 200 non-null object
Fivth 200 non-null object
Sixth 200 non-null object
dtypes: object(6)
memory usage: 9.5+ KB

What is data.info() telling you?

Zeugma
– Zeugma

2016-11-22 19:51:20 +00:00
Commented Nov 22, 2016 at 19:51 — Zeugma
– Zeugma, Commented Nov 22, 2016 at 19:51
I added the data.info() output into the question.

dif
– dif

2016-11-22 19:55:40 +00:00
Commented Nov 22, 2016 at 19:55 — dif
– dif, Commented Nov 22, 2016 at 19:55

jezrael · Accepted Answer · 2016-11-22 19:55:57Z

3

You can convert all data to_timedelta and then to total_seconds - integers, so can be plot. Apply is used because to_timedelta works only with Series (columns of df)

data = data.apply(lambda x: pd.to_timedelta(x).dt.total_seconds())

data.plot.bar()

answered Nov 22, 2016 at 19:55

jezrael

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2 Comments

dif Over a year ago

Oh, thanks for the quick response! This works! So it looks like DataFrame.plot() only works on "real" numerical values?

jezrael Over a year ago

I think it looks no see - github.com/pandas-dev/pandas/issues/8711

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