CODEWITHSUNDEEP
pythonnumpymatplotlib
Will
Will

Reputation: 737

Python plot lines with specific x values from numpy

I have a situation with a bunch of datafiles, these datafiles have a number of samples in a given time frame that depends on the system. i.e. At time t=1 for instance I might have a file with 10 items, or 20 items, at later times in that file I will always have the same number of items. The format is time, x, y, z in columns, and loaded into a numpy array. The time values show which frame, but as mentioned there's always the same, let's go with 10 as a sample. So I'll have a (10,4) numpy array where the time values are identical, but there are many frames in the file, so lets say 100 frames, so really I have (1000,4). I want to plot the data with time on the x-axis and manipulations of the other data on the y, but I am unsure how to do this with line plot methods in matplotlib. Normally to provide both x,y values I believe I need to do a scatter plot, so I'm hoping there's a better way to do this. What I ideally want is to treat each line that has the same time code as a different series (so it will colour differently), and the next bit of data for that same line number in the next frame (time value) will be labelled the same colour, giving those good contiguous lines. We can look at the time column and figure out how many items share a time code, let's call it "n". Sample code:

a = numpy.loadtxt('sampledata.txt')
plt.plot(a[:0,:,n],a[:1,:1])
plt.show()

I think this code expresses what I'm going for, though it doesn't work.

Upvotes: 0

Views: 192

Answers (2)

Will
Will

Reputation: 737

Alternative, the method I used, but Tim's answer is still accurate as well. Since the time codes are not date/time information I modified my own code to add tags as a second column I call "p" (they're polymers).

import numpy as np
import pandas as pd
datain = np.loadtxt('somefile.txt')
df = pd.DataFrame(data = datain, columns = ["t","p","x","y","z"])
ax = sns.scatterplot("t","x", data = df, hue = "p")
plt.show()

And of course the other columns can be plotted similarly if desired.

Upvotes: 1

Tim
Tim

Reputation: 161

Edit: I hope this is what you wanted.

seaborn scatterplot can categorize data to some groups which have the same codes (time code in this case) and use the same colors to them.

import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns

df = pd.read_csv(r"E:\Programming\Python\Matplotlib\timecodes.csv",
                 names=["time","x","y","z","code"]) #use your file

df["time"]=pd.to_datetime(df["time"]) #recognize the data as Time
df["x"]=df["time"].dt.day # I changed the data into "Date only" and imported to x column. Easier to see on graph.

#just used random numbers in y and z in my data.
sns.scatterplot("x", "y", data = df, hue = "code") #hue does the grouping

plt.show()

I used csv file here but you can do to your text file as well by adding sep="\t" in the argument. I also added a code in the file. If you have it the code can group the data in the graph, so you don't have to separate or make a hierarchical index. If you want to change colors or grouping please see seaborn website.

Hope this helps.

Upvotes: 1

Related Questions