# [Numpy-discussion] arrays and : behaviour

did did 21did21 at gmx.com
Thu May 1 07:31:26 EDT 2014

```Hello all and sorry for my bad english,

i am a beginner with python and i try to save a lot of data in several folders in a 4D matrix
and then to plot two columns of this 4D matrix.

Bellow, i have the code to fill my 4D matrix, it works very well :

[CODE]matrix4D=[]
for i in Numbers:
matrix3D=[]
for j in listeOfdata:
nameOfFile=filePrefixe+i+"-"+j+extensionTXT
matrix3D.append(matrix2D)
matrix4D.append(matrix3D)
array4D = np.asarray(matrix4D)[/CODE]

But now, i want to plot the third column as function of the third too (just for trying) and i use
this stupid manner that works well :

[CODE]plt.figure(1)
temp=plt.plot(array4D[0][0][0][0],array4D[0][0][0][0],'bo')
temp=plt.plot(array4D[0][0][1][0],array4D[0][0][1][0],'bo')
temp=plt.plot(array4D[0][0][2][0],array4D[0][0][2][0],'bo')
temp=plt.plot(array4D[0][0][3][0],array4D[0][0][3][0],'bo')
plt.show()[/CODE]

Now, i want to use a more smart manner and i use ":" like this

[CODE]plt.figure(1)
temp=plt.plot(array4D[0][0][0:3][0],array4D[0][0][0:3][0],'bo')
plt.show()[/CODE]

The result should be the same but i don't got the same results!!!

In attachement you have the two corresponding plots, can you explain to me with
i don't have the same plots ??

thanks for all
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```