# Concatenating Numpy Vectors Stored In Files

Sometimes you have vectors or matrices stored in files, and you need to read them and concatenate them. One way of doing this is reading them into a list and then using Numpy’s hstack or vstack to create the vector or matrix. Like this for concatenating rows

```
result = np.hstack([np.genfromtxt(fName,delimiter=";") for fName in fList])
```

where the read matrix or vector all are of size `MxNf`

, that is the rows, `M`

, are the same across all read matrices while `Nf`

can vary. The same goes for vertical stacking but then the sizes are reversed, that is, `NfxM`

, and we have,

```
result = np.vstack([np.genfromtxt(fName,delimiter=";") for fName in fList])
```