**In this article:**

- A simple graphic with pyplot
- Using lists for graphic coordinates
- A graphic with many lines
- Using tuples for graphic coordinates
- What happen when lists or tuples for coordinates have different size?
- Save graphic in a file

## 1. A simple graphic with pyplot

Most simple graphic with matplotlib is plotting with pyplot interface:

import matplotlib.pyplot as myplot

myplot.plot([1, 5], [2, 12])

myplot.show()

This show graphic like below:

From image result that pyplot draw a line between two points (1,2) and (5,12)

## 2. Using lists for graphic coordinates

Arguments for “plot” in myplot.plot([1, 5], [2, 12]) are 2 lists:

l1 = [1, 5]

l2 = [2, 12]

The same graphic is obtained using:

import matplotlib.pyplot as myplot

l1 = [1, 5]

l2 = [2, 12]

myplot.plot(l1, l2)

myplot.show()

In this case line draw is between

point 1 with coordinates:

x=first element of list l1, or l1[0]

y=first element of list l2, or l2[0]

point 2 with coordinates:

x=second element of list l1, or l1[1]

y=second element of list l2, or l2[1]

## 3. A graphic with many lines

If lists l1 and l2 have more elements, plot will draw line(es) between appropriate points. For example:

import matplotlib.pyplot as myplot

l1 = [1, 3, 5]

l2 = [2, 4, 12]

myplot.plot(l1, l2)

myplot.show()

Code will draw:

In this case lines are between points that have coordinates:

(1,2), (3,4), (5,12)

or

(l1[0],l2[0]), (l1[0],l2[0]), (l1[0],l2[0])

## 4. Using tuples for graphic coordinates

The same graphic is obtained if we use tuples, i.e. code:

import matplotlib.pyplot as myplot

t1 = (1, 3, 5)

t2 = (2, 4, 12)

myplot.plot(t1, t2)

myplot.show()

Lists or tuples can have more elements, it is important that those to have

the same number of elements.

## 5. What happen when lists or tuples for coordinates have different size?

If we try with different elements, for example code:

import matplotlib.pyplot as myplot

l1 = [1, 3, 5]

l2 = [2, 4, 7, 12]

myplot.plot(l1, l2)

myplot.show()

this will fail with error:

ValueError: x and y must have same first dimension, but have shapes (3,) and (4,)

## 6. Save graphic in a file

Command myplot.show() display effectively resulted graphic.

Using savefig() graphic is saved in a file for example:

import matplotlib.pyplot as myplot

l1 = [1, 3, 5]

l2 = [2, 4, 12]

myplot.plot(l1, l2)

myplot.savefig(“C:\tmp\fig1.png”)

Here savefig method is used with only one parameter, the file path.

Method savefig have many more parameters, like **here**.

Above code will save graphic in file C:\tmp\fig1.png